Answer: For each of the following elements, write its chemical symbol, determine the

A charged particle moves between two electrically charged plates, as shown here. (a) What is the sign of the electrical charge on the particle? (b) As the charge on the plates is increased, would you expect the bending to increase, decrease, or stay the same? (c) As the mass of the particle is increased while the speed of the particles remains the same, would you expect the bending to increase, decrease, or stay the same? [Section 2.2]

The following diagram is a representation of 20 atoms of a fictitious element, which we will call nevadium (Nv). The red spheres are 293Nv, and the blue spheres are 295Nv. (a) Assuming that this sample is a statistically representative sample of the element, calculate the percent abundance of each element. (b) If the mass of 293Nv is 293.15 amu and that of 295Nv is 295.15 amu, what is the atomic weight of Nv? [Section 2.4]

Four of the boxes in the following periodic table are colored. Which of these are metals and which are nonmetals? Which one is an alkaline earth metal? Which one is a noble gas? [Section 2.5]

Does the following drawing represent a neutral atom or an ion? Write its complete chemical symbol, including mass number, atomic number, and net charge (if any). [Sections 2.3 and 2.7]

Which of the following diagrams most likely represents an ionic compound, and which represents a molecular one? Explain your choice. [Sections 2.6 and 2.7]

Write the chemical formula for the following compound. Is the compound ionic or molecular? Name the compound. [Sections 2.6 and 2.8]

Five of the boxes in the following periodic table are colored. Predict the charge on the ion associated with each of these elements. [Section 2.7]

The following diagram represents an ionic compound in which the red spheres represent cations and the blue spheres represent anions. Which of the following formulas is consistent with the drawing? KBr, K2SO4, Ca(NO3)2, Fe2(SO4)3. Name the compound. [Sections 2.7 and 2.8]

Are these two compounds isomers? Explain. [Section 2.9]

In the Millikan oil-drop experiment (see Figure 2.5), the tiny oil drops are observed through the viewing lens as rising, stationary, or falling, as shown here. (a) What causes their rate of fall to vary from their rate in the absence of an electric field? (b) Why do some drops move upward? [Section 2.2]

A chemist finds that 30.82 g of nitrogen will react with 17.60, 35.20, 70.40, or 88.00 g of oxygen to form four different compounds. (a) Calculate the mass of oxygen per gram of nitrogen in each compound. (b) How do the numbers in part (a) support Dalton’s atomic theory?

Hydrogen sulfide is composed of two elements: hydrogen and sulfur. In an experiment, 6.500 g of hydrogen sulfide is fully decomposed into its elements. (a) If 0.384 g of hydrogen is obtained in this experiment, how many grams of sulfur must be obtained? (b) What fundamental law does this experiment demonstrate?

A chemist finds that 30.82 g of nitrogen will react with 17.60, 35.20, 70.40, or 88.00 g of oxygen to form four different compounds. (a) Calculate the mass of oxygen per gram of nitrogen in each compound. (b) How do the numbers in part (a) support Dalton’s atomic theory?

What is the molecular formula of hopane?

Which of the three subatomic particles was discovered first— the proton, neutron, or electron? Which one was discovered last?

An unknown particle is caused to move between two electrically charged plates, as illustrated in Figure 2.7. You hypothesize that the particle is a proton. (a) If your hypothesis is correct, would the particle be deflected in the same or opposite direction as the rays? (b) Would it be deflected by a smaller or larger amount than the rays?

What fraction of the particles in Rutherford’s gold foil experiment are scattered at large angles? Assume the gold foil is two layers thick, as shown in Figure 2.9, and that the approximate diameters of a gold atom and its nucleus are 2.7 Å and 1.0 10–4 , respectively. Hint: Calculate the cross sectional area occupied by the nucleus as a fraction of that occupied by the atom. Assume that the gold nuclei in each layer are offset from each other.

Millikan determined the charge on the electron by studying the static charges on oil drops falling in an electric field (Figure 2.5). A student carried out this experiment using several oil drops for her measurements and calculated the charges on the drops. She obtained the following data: (a) What is the significance of the fact that the droplets carried different charges? (b) What conclusion can the student draw from these data regarding the charge of the electron? (c) What value (and to how many significant figures) should she report for the electronic charge?

The radius of an atom of gold (Au) is about 1.35 . (a) Express this distance in nanometers (nm) and in picometers (pm). (b) How many gold atoms would have to be lined up to span 1.0 mm? (c) If the atom is assumed to be a sphere, what is the volume in cm3 of a single Au atom?

An atom of rhodium (Rh) has a diameter of about 2.7 10-8 cm. (a) What is the radius of a rhodium atom in angstroms () and in meters (m)? (b) How many Rh atoms would have to be placed side by side to span a distance of 6.0 m? (c) If you assume that the Rh atom is a sphere, what is the volume in m3 of a single atom?

Answer the following questions without referring to Table 2.1: (a) What are the main subatomic particles that make up the atom? (b) What is the relative charge (in multiples of the electronic charge) of each of the particles? (c) Which of the particles is the most massive? (d) Which is the least massive?

Determine whether each of the following statements is true or false. If false, correct the statement to make it true: (a) The nucleus has most of the mass and comprises most of the volume of an atom. (b) Every atom of a given element has the same number of protons. (c) The number of electrons in an atom equals the number of neutrons in the atom. (d) The protons in the nucleus of the helium atom are held together by a force called the strong nuclear force.

Consider an atom of 10B. (a) How many protons, neutrons, and electrons does this atom contain? (b) What is the symbol of the atom obtained by adding one proton to 10B? (c) What is the symbol of the atom obtained by adding one neutron to 10B? (d) Are either of the atoms obtained in parts (b) and (c) isotopes of 10B? If so, which one?

Consider an atom of 63Cu. (a) How many protons, neutrons, and electrons does this atom contain? (b) What is the symbol of the ion obtained by removing two electrons from 63Cu? (c) What is the symbol for the isotope of 63Cu that possesses 36 neutrons?

(a) Define atomic number and mass number. (b) Which of these can vary without changing the identity of the element?

(a) Which two of the following are isotopes of the same element: \({ }_{16}^{31} X,{ }_{15}^{31} X,{ }_{16}^{32} X\)? (b) What is the identity of the element whose isotopes you have selected? Text Transcription: _16^31X,_15^31X, _16^32X

How many protons, neutrons, and electrons are in the following atoms? (a) 40Ar, (b) 65Zn, (c) 70Ga, (d) 80Br, (e) 184W, (f) 243Am.

Each of the following isotopes is used in medicine. Indicate the number of protons and neutrons in each isotope: (a) phosphorus-32, (b) chromium-51, (c) cobalt-60, (d) technetium-99, (e) iodine-131, (f) thallium-201.

Pheromones are chemical compounds that animals, especially insects, use to signal others of the same species. Female tiger moths, for example, signify their presence to male moths this way. The sex attractant is a 2-methyl-branched alkane having a molecular weight of 254. What is its structure?

Fill in the gaps in the following table, assuming each column represents a neutral atom.

Write the correct symbol, with both superscript and subscript, for each of the following. Use the list of elements in the front inside cover as needed: (a) the isotope of platinum that contains 118 neutrons, (b) the isotope of krypton with mass number 84, (c) the isotope of arsenic with mass number 75, (d) the isotope of magnesium that has an equal number of protons and neutrons.

One way in which Earth’s evolution as a planet can be understood is by measuring the amounts of certain isotopes in rocks. One quantity recently measured is the ratio of 129Xe to 130Xe in some minerals. In what way do these two isotopes differ from one another? In what respects are they the same?

(a) What isotope is used as the standard in establishing the atomic mass scale? (b) The atomic weight of boron is reported as 10.81, yet no atom of boron has the mass of 10.81 amu. Explain.

(a) What is the mass in amu of a carbon-12 atom? (b) Why is the atomic weight of carbon reported as 12.011 in the table of elements and the periodic table in the front inside cover of this text?

Only two isotopes of copper occur naturally: 63Cu (atomic mass = 62.9296 amu; abundance 69.17%) and 65Cu (atomic mass = 64.9278 amu; abundance 30.83%). Calculate the atomic weight (average atomic mass) of copper.

Rubidium has two naturally occurring isotopes, rubidium-85 1atomic mass = 84.9118 amu; abundance = 72.15%2 and rubidium-87 1atomic mass = 86.9092 amu; abundance = 27.85%2. Calculate the atomic weight of rubidium.

(a) Thomson’s cathode-ray tube (Figure 2.4) and the mass spectrometer (Figure 2.11) both involve the use of electric or magnetic fields to deflect charged particles. What are the charged particles involved in each of these experiments? (b) What are the labels on the axes of a mass spectrum? (c) To measure the mass spectrum of an atom, the atom must first lose one or more electrons. Which would you expect to be deflected more by the same setting of the electric and magnetic fields, a Cl+ or a Cl2+ ion?

Consider the mass spectrometer shown in Figure 2.11. Determine whether each of the following statements is true or false. If false, correct the statement to make it true: (a) The paths of neutral (uncharged) atoms are not affected by the magnet. (b) The height of each peak in the mass spectrum is inversely proportional to the mass of that isotope. (c) For a given element, the number of peaks in the spectrum is equal to the number of naturally occurring isotopes of that element.

Naturally occurring magnesium has the following isotopic abundances: (a) What is the average atomic mass of Mg? (b) Sketch the mass spectrum of Mg.

Mass spectrometry is more often applied to molecules than to atoms. We will see in Chapter 3 that the molecular weight of a molecule is the sum of the atomic weights of the atoms in the molecule. The mass spectrum of H2 is taken under conditions that prevent decomposition into H atoms. The two naturally occurring isotopes of hydrogen are 1H (atomic mass = 1.00783 amu; abundance 99.9885%) and 2H (atomic mass = 2.01410 amu; abundance 0.0115%). (a) How many peaks will the mass spectrum have? (b) Give the relative atomic masses of each of these peaks. (c) Which peak will be the largest, and which the smallest?

For each of the following elements, write its chemical symbol, locate it in the periodic table, give its atomic number, and indicate whether it is a metal, metalloid, or nonmetal: (a) chromium, (b) helium, (c) phosphorus, (d) zinc, (e) magnesium, (f) bromine, (g) arsenic.

Locate each of the following elements in the periodic table; give its name and atomic number, and indicate whether it is a metal, metalloid, or nonmetal: (a) Li, (b) Sc, (c) Ge, (d) Yb, (e) Mn, (f) Sb, (g) Xe.

For each of the following elements, write its chemical symbol, determine the name of the group to which it belongs (Table 2.3), and indicate whether it is a metal, metalloid, or nonmetal: (a) potassium, (b) iodine, (c) magnesium, (d) argon, (e) sulfur.

The elements of group 4A show an interesting change in properties moving down the group. Give the name and chemical symbol of each element in the group and label it as a nonmetal, metalloid, or metal.

The reaction shown is important in the industrial preparation of dichlorodimethylsilane for eventual conversion to silicone polymers. \(2 \mathrm{CH_3Cl+Si \longrightarrow\left(CH_3\right)_{2} SiCl_2}\) (a) Is carbon oxidized, reduced, or neither in this reaction? (b) On the basis of the molecular model of \(\mathrm{(CH_3)_2SiCl_2}\), deduce the hybridization state of silicon in this compound. What is the principal quantum number n of the silicon s and p orbitals that are hybridized? Text Transcription: 2 \mathrm{CH_3Cl+Si \longrightarrow\left(CH_3\right)_{2} SiCl_2} \mathrm{(CH_3)_2SiCl_2}

Ball-and-stick representations of benzene, a colorless liquid often used in organic chemistry reactions, and acetylene, a gas used as a fuel for high-temperature welding, are shown below. (a) Determine the molecular formula of each. (b) Determine the empirical formula of each.

What are the molecular and empirical formulas for each of the following compounds?

Two substances have the same molecular and empirical formulas. Does this mean that they must be the same compound?

Write the empirical formula corresponding to each of the following molecular formulas: (a) Al2Br6, (b) C8H10, (c) C4H8O2, (d) P4O10, (e) C6H4Cl2, (f) B3N3H6.

Determine the molecular and empirical formulas of the following: (a) the organic solvent benzene, which has six carbon atoms and six hydrogen atoms; (b) the compound silicon tetrachloride, which has a silicon atom and four chlorine atoms and is used in the manufacture of computer chips; (c) the reactive substance diborane, which has two boron atoms and six hydrogen atoms; (d) the sugar called glucose, which has six carbon atoms, twelve hydrogen atoms, and six oxygen atoms.

How many hydrogen atoms are in each of the following: (a) C2H5OH, (b) Ca(C2H5COO)2, (c) (NH4)3PO4?

How many of the indicated atoms are represented by each chemical formula: (a) carbon atoms in C4H9COOCH3, (b) oxygen atoms in Ca(ClO3)2, (c) hydrogen atoms in (NH4)2HPO4?

Write the molecular and structural formulas for the compounds represented by the following molecular models:

Write the molecular and structural formulas for the compounds represented by the following models:

Fill in the gaps in the following table:

Fill in the gaps in the following table:

Each of the following elements is capable of forming an ion in chemical reactions. By referring to the periodic table, predict the charge of the most stable ion of each: (a) Mg, (b) Al, (c) K, (d) S, (e) F.

Using the periodic table, predict the charges of the ions of the following elements: (a) Ga, (b) Sr, (c) As, (d) Br, (e) Se.

Using the periodic table to guide you, predict the chemical formula and name of the compound formed by the following elements: (a) Ga and F, (b) Li and H, (c) Al and I, (d) K and S.

The most common charge associated with scandium in its compounds is 3+. Indicate the chemical formulas you would expect for compounds formed between scandium and (a) iodine, (b) sulfur, (c) nitrogen.

Predict the chemical formula for the ionic compound formed by (a) Ca2+ and Br-, (b) K+ and CO32-, (c) Al3+ and CH3COO-, (d) NH4+ and SO42-, (e) Mg2+ and PO43-.

Predict the chemical formulas of the compounds formed by the following pairs of ions: (a) Cr3+ and Br-, (b) Fe3+ and O2-, (c) Hg22+ and CO32-, (d) Ca2+ and ClO3-, (e) NH4+ and PO43-.

Complete the table by filling in the formula for the ionic compound formed by each pair of cations and anions, as shown for the first pair.

Complete the table by filling in the formula for the ionic compound formed by each pair of cations and anions, as shown for the first pair.

Predict whether each of the following compounds is molecular or ionic: (a) B2H6, (b) CH3OH, (c) LiNO3, (d) Sc2O3, (e) CsBr, (f) NOCl, (g) NF3, (h) Ag2SO4.

Which of the following are ionic, and which are molecular? (a) PF5, (b) NaI, (c) SCl2, (d) Ca(NO3)2, (e) FeCl3, (f) LaP, (g) CoCO3, (h) N2O4.

Give the chemical formula for (a) chlorite ion, (b) chloride ion, (c) chlorate ion, (d) perchlorate ion, (e) hypochlorite ion.

Selenium, an element required nutritionally in trace quantities, forms compounds analogous to sulfur. Name the following ions: (a) SeO42-, (b) Se2-, (c) HSe-, (d) HSeO3-.

Give the names and charges of the cation and anion in each of the following compounds: (a) CaO, (b) Na2SO4, (c) KClO4, (d) Fe(NO3)2, (e) Cr(OH)3.

Give the names and charges of the cation and anion in each of the following compounds: (a) CuS, (b) Ag2SO4, (c) Al(ClO3)3, (d) Co(OH)2, (e) PbCO3.

Name the following ionic compounds: (a) Li2O, (b) FeCl3, (c) NaClO, (d) CaSO3, (e) Cu(OH)2, (f ) Fe(NO3)2, (g) Ca(CH3COO)2, (h) Cr2(CO3)3, (i) K2CrO4, (j) (NH4)2SO4.

Name the following ionic compounds: (a) KCN, (b) NaBrO2, (c) Sr(OH)2, (d) CoTe, (e) Fe2(CO3)3, (f ) Cr(NO3)3, (g) (NH4)2SO3, (h) NaH2PO4, (i) KMnO4, (j) Ag2Cr2O7.

Write the chemical formulas for the following compounds: (a) aluminum hydroxide, (b) potassium sulfate, (c) copper(I) oxide, (d) zinc nitrate, (e) mercury(II) bromide, (f) iron(III) carbonate, (g) sodium hypobromite.

Give the chemical formula for each of the following ionic compounds: (a) sodium phosphate, (b) zinc nitrate, (c) barium bromate, (d) iron(II) perchlorate, (e) cobalt(II) hydrogen carbonate, (f) chromium(III) acetate, (g) potassium dichromate.

Give the name or chemical formula, as appropriate, for each of the following acids: (a) HBrO3, (b) HBr, (c) H3PO4, (d) hypochlorous acid, (e) iodic acid, (f) sulfurous acid.

Provide the name or chemical formula, as appropriate, for each of the following acids: (a) hydroiodic acid, (b) chloric acid, (c) nitrous acid, (d) H2CO3, (e) HClO4, (f) CH3COOH.

Give the name or chemical formula, as appropriate, for each of the following binary molecular substances: (a) SF6, (b) IF5, (c) XeO3, (d) dinitrogen tetroxide, (e) hydrogen cyanide, (f) tetraphosphorus hexasulfide.

The oxides of nitrogen are very important components in urban air pollution. Name each of the following compounds: (a) N2O, (b) NO, (c) NO2, (d) N2O5, (e) N2O4.

Write the chemical formula for each substance mentioned in the following word descriptions (use the front inside cover to find the symbols for the elements you do not know). (a) Zinc carbonate can be heated to form zinc oxide and carbon dioxide. (b) On treatment with hydrofluoric acid, silicon dioxide forms silicon tetrafluoride and water. (c) Sulfur dioxide reacts with water to form sulfurous acid. (d) The substance phosphorus trihydride, commonly called phosphine, is a toxic gas. (e) Perchloric acid reacts with cadmium to form cadmium(II) perchlorate. (f) Vanadium(III) bromide is a colored solid.

Assume that you encounter the following sentences in your reading. What is the chemical formula for each substance mentioned? (a) Sodium hydrogen carbonate is used as a deodorant. (b) Calcium hypochlorite is used in some bleaching solutions. (c) Hydrogen cyanide is a very poisonous gas. (d) Magnesium hydroxide is used as a cathartic. (e) Tin(II) fluoride has been used as a fluoride additive in toothpastes. (f) When cadmium sulfide is treated with sulfuric acid, fumes of hydrogen sulfide are given off.

(a) What is a hydrocarbon? (b) Pentane is the alkane with a chain of five carbon atoms. Write a structural formula for this compound and determine its molecular and empirical formulas.

(a) What is meant by the term isomer? (b) Among the four alkanes, ethane, propane, butane, and pentane, which is capable of existing in isomeric forms?

(a) What is a functional group? (b) What functional group characterizes an alcohol? (c) Write a structural formula for 1-pentanol, the alcohol derived from pentane by making a substitution on one of the carbon atoms.

Consider the following organic substances: ethanol, propane, hexane, and propanol. (a) Which of these molecules contains an OH group? (b) Which of these molecules contains three carbon atoms?

Chloropropane is derived from propane by substituting Cl for H on one of the carbon atoms. (a) Draw the structural formulas for the two isomers of chloropropane. (b) Suggest names for these two compounds.

Draw the structural formulas for three isomers of pentane, C5H12.

Suppose a scientist repeats the Millikan oil-drop experiment but reports the charges on the drops using an unusual (and imaginary) unit called the warmomb (wa). The scientist obtains the following data for four of the drops: (a) If all the droplets were the same size, which would fall most slowly through the apparatus? (b) From these data, what is the best choice for the charge of the electron in warmombs? (c) Based on your answer to part (b), how many electrons are there on each of the droplets? (d) What is the conversion factor between warmombs and coulombs?

The natural abundance of 3He is 0.000137%. (a) How many protons, neutrons, and electrons are in an atom of 3He? (b) Based on the sum of the masses of their subatomic particles, which is expected to be more massive, an atom of 3He or an atom of 3H (which is also called tritium)? (c) Based on your answer to part (b), what would need to be the precision of a mass spectrometer that is able to differentiate between peaks that are due to 3He+ and 3H+?

A cube of gold that is 1.00 cm on a side has a mass of 19.3 g. A single gold atom has a mass of 197.0 amu. (a) How many gold atoms are in the cube? (b) From the information given, estimate the diameter in Å of a single gold atom. (c) What assumptions did you make in arriving at your answer for part (b)?

The diameter of a rubidium atom is 4.95 . We will consider two different ways of placing the atoms on a surface. In arrangement A, all the atoms are lined up with one another to form a square grid. Arrangement B is called a close-packed arrangement because the atoms sit in the “depressions” formed by the previous row of atoms: (a) Using arrangement A, how many Rb atoms could be placed on a square surface that is 1.0 cm on a side? (b) How many Rb atoms could be placed on a square surface that is 1.0 cm on a side, using arrangement B? (c) By what factor has the number of atoms on the surface increased in going to arrangement B from arrangement A? If extended to three dimensions, which arrangement would lead to a greater density for Rb metal?

(a) Assuming the dimensions of the nucleus and atom shown in Figure 2.10, what fraction of the volume of the atom is taken up by the nucleus? (b) Using the mass of the proton from Table 2.1 and assuming its diameter is \(1.0 \times 10^{-15}\) m, calculate the density of a proton in \(\mathrm{g /cm^3}\). Text Transcription: 1.0 \times 10^{-15} \mathrm{g /cm^3}

Identify the element represented by each of the following symbols and give the number of protons and neutrons in each: (a) \({ }_{33}^{74} X\) (b) \({ }_{53}^{127} X\) (c) \({ }_{63}^{152} X\) (d) \({ }_{83}^{209} X\) Text Transcription: _33^74X _53^127X _63^152X _83^209X

The nucleus of 6Li is a powerful absorber of neutrons. It exists in the naturally occurring metal to the extent of 7.5%. In the era of nuclear deterrence, large quantities of lithium were processed to remove 6Li for use in hydrogen bomb production. The lithium metal remaining after removal of 6Li was sold on the market. (a) What are the compositions of the nuclei of 6Li and 7Li? (b) The atomic masses of 6Li and 7Li are 6.015122 and 7.016004 amu, respectively. A sample of lithium depleted in the lighter isotope was found on analysis to contain 1.442% 6Li. What is the average atomic weight of this sample of the metal?

The element oxygen has three naturally occurring isotopes, with 8, 9, and 10 neutrons in the nucleus, respectively. (a) Write the full chemical symbols for these three isotopes. (b) Describe the similarities and differences between the three kinds of atoms of oxygen.

The element lead (Pb) consists of four naturally occurring isotopes with atomic masses 203.97302, 205.97444, 206.97587, and 207.97663 amu. The relative abundances of these four isotopes are 1.4, 24.1, 22.1, and 52.4%, respectively. From these data, calculate the atomic weight of lead.

Gallium (Ga) consists of two naturally occurring isotopes with masses of 68.926 and 70.925 amu. (a) How many protons and neutrons are in the nucleus of each isotope? Write the complete atomic symbol for each, showing the atomic number and mass number. (b) The average atomic mass of Ga is 69.72 amu. Calculate the abundance of each isotope.

Using a suitable reference such as the CRC Handbook of Chemistry and Physics or http://www.webelements.com, look up the following information for nickel: (a) the number of known isotopes, (b) the atomic masses (in amu), (c)the natural abundances of the five most abundant isotopes.

There are two different isotopes of bromine atoms. Under normal conditions, elemental bromine consists of Br2 molecules, and the mass of a Br2 molecule is the sum of the masses of the two atoms in the molecule. The mass spectrum of Br2 consists of three peaks: (a) What is the origin of each peak (of what isotopes does each consist)? (b) What is the mass of each isotope? (c) Determine the average molecular mass of a Br2 molecule. (d) Determine the average atomic mass of a bromine atom. (e) Calculate the abundances of the two isotopes.

It is common in mass spectrometry to assume that the mass of a cation is the same as that of its parent atom. (a) Using data in Table 2.1, determine the number of significant figures that must be reported before the difference in masses of 1H and 1H+ is significant. (b) What percentage of the mass of an 1H atom does the electron represent?

From the following list of elements—Ar, H, Ga, Al, Ca, Br, Ge, K, O—pick the one that best fits each description. Use each element only once: (a) an alkali metal, (b) an alkaline earth metal, (c) a noble gas, (d) a halogen, (e) a metalloid, (f) a nonmetal listed in group 1A, (g) a metal that forms a 3+ ion, (h) a nonmetal that forms a 2- ion, (i) an element that resembles aluminum.

The first atoms of seaborgium (Sg) were identified in 1974. The longest-lived isotope of Sg has a mass number of 266. (a) How many protons, electrons, and neutrons are in an 266Sg atom? (b) Atoms of Sg are very unstable, and it is therefore difficult to study this element’s properties. Based on the position of Sg in the periodic table, what element should it most closely resemble in its chemical properties?

The explosion of an atomic bomb releases many radioactive isotopes, including strontium-90. Considering the location of strontium in the periodic table, suggest a reason for the fact that this isotope is particularly dangerous for human health.

A U.S. 1-cent coin (a penny) has a diameter of 19 mm and a thickness of 1.5 mm. Assume the coin is made of pure copper, whose density and approximate market price are 8.9 g/cm3 and $2.40 per pound, respectively. Calculate the value of the copper in the coin, assuming its thickness is uniform.

The U.S. Mint produces a dollar coin called the American Silver Eagle that is made of nearly pure silver. This coin has a diameter of 41 mm and a thickness of 2.5 mm. The density and approximate market price of silver are 10.5 g/cm3 and $0.51 per gram, respectively. Calculate the value of the silver in the coin, assuming its thickness is uniform.

From the molecular structures shown here, identify the one that corresponds to each of the following species: (a) chlorine gas; (b) propane; (c) nitrate ion; (d) sulfur trioxide; (e) methyl chloride, CH3Cl.

Name each of the following oxides. Assuming that the compounds are ionic, what charge is associated with the metallic element in each case? (a) NiO, (b) MnO2, (c) Cr2O3, (d) MoO3.

Fill in the blanks in the following table:

Cyclopropane is an interesting hydrocarbon. Instead of having three carbons in a row, the three carbons form a ring, as shown in this perspective drawing (see Figure 2.18 for a prior example of this kind of drawing): Cyclopropane was at one time used as an anesthetic, but its use was discontinued, in part because it is highly flammable. (a) What is the empirical formula of cyclopropane? How does it differ from that of propane? (b) The three carbon atoms are necessarily in a plane. What do the different wedges mean? (c) What change would you make to the structure shown to illustrate chlorocyclopropane? Are there isomers of chlorocyclopropane?

Elements in the same group of the periodic table often form oxyanions with the same general formula. The anions are also named in a similar fashion. Based on these observations, suggest a chemical formula or name, as appropriate, for each of the following ions: (a) BrO4-, (b) SeO32-, (c) arsenate ion, (d) hydrogen tellurate ion.

Carbonic acid occurs in carbonated beverages. When allowed to react with lithium hydroxide, it produces lithium carbonate. Lithium carbonate is used to treat depression and bipolar disorder. Write chemical formulas for carbonic acid, lithium hydroxide, and lithium carbonate.

Give the chemical names of each of the following familiar compounds: (a) NaCl (table salt), (b) NaHCO3 (baking soda), (c) NaOCl (in many bleaches), (d) NaOH (caustic soda), (e) (NH4)2CO3 (smelling salts), (f) CaSO4 (plaster of Paris).

Many familiar substances have common, unsystematic names. For each of the following, give the correct systematic name: (a) salt peter, KNO3; (b) soda ash, Na2CO3; (c) lime, CaO; (d) muriatic acid, HCl; (e) Epsom salts, MgSO4; (f) milk of magnesia, Mg(OH)2.

Because many ions and compounds have very similar names, there is great potential for confusing them. Write the correct chemical formulas to distinguish between (a) calcium sulfide and calcium hydrogen sulfide, (b) hydrobromic acid and bromic acid, (c) aluminum nitride and aluminum nitrite, (d) iron(II) oxide and iron(III) oxide, (e) ammonia and ammonium ion, (f) potassium sulfite and potassium bisulfite, (g) mercurous chloride and mercuric chloride, (h) chloric acid and perchloric acid.

In what part of the atom does the strong nuclear force operate?

Construct a diagram similar to Figure 2.5 for diatomic helium (He2). Why is helium monatomic instead of diatomic?

Identify the orbital overlaps of all of the bonds in propene (H2C=CHCH3) and classify them as \(\sigma\) or \(\pi\) as appropriate. Text Transcription: sigma pi

The hydrocarbon shown, called vinylacetylene, is used in the synthesis of neoprene, a synthetic rubber. Identify the orbital overlaps involved in the indicated bond. How many \(\sigma\) bonds are there in vinylacetylene? How many \(\pi\) bonds? Text Transcription: sigma pi

An n-alkane of molecular formula C28H58 has been isolated from a certain fossil plant. Write a condensed structural formula for this alkane.

Much of the communication between insects involves chemical messengers called pheromones. A species of cockroach secretes a substance from its mandibular glands that alerts other cockroaches to its presence and causes them to congregate. One of the principal components of this aggregation pheromone is the alkane shown. Give the molecular formula of this substance, and represent it by a condensed formula.

Write condensed and bond-line formulas for the five isomeric C6H14 alkanes.

Give the IUPAC names for (a) The isomers of C4H10 (b) The isomers of C5H12

Give the structures and IUPAC names of all the C5H11 alkyl groups, and identify them as primary, secondary, or tertiary, as appropriate.

Give an acceptable IUPAC name for each of the following alkanes:

Name each of the following compounds:

Given the standard enthalpies of formation \(\left(\Delta H_{f}^{\circ}\right)\) of cyclopropane (39.30 kJ/mol) and cyclohexane (?124.6 kJ/mol), calculate \(\Delta H^{\circ}\) for the reaction: Text Transcription: (Delta H_f^circ) Delta H^circ

Both of the following reactions will be encountered later in this text. One is oxidation–reduction, the other is not. Which is which?

Which of the following reactions requires an oxidizing agent, a reducing agent, or neither? (b) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{Br} \quad \longrightarrow \quad \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{Li}\) (c) \(\mathrm{H}_{2} \mathrm{C}=\mathrm{CH}_{2} \quad \longrightarrow \quad \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}\) Text Transcription: CH_3CH_2Br longrightarrow CH_3CH_2Li H_2C=CH_2 longrightarrow CH_3CH_2OH

The general molecular formula for alkanes is CnH2n+2. What is the general molecular formula for: (a) Cycloalkanes (b) Alkenes (c) Alkynes (d) Cyclic hydrocarbons that contain one double bond

A certain hydrocarbon has a molecular formula of C5H8. Which of the following is not a structural possibility for this hydrocarbon? (a) It is a cycloalkane. (b) It contains one ring and one double bond. (c) It contains two double bonds and no rings. (d) It is an alkyne.

Which of the hydrocarbons in each of the following groups are isomers?

Write the structural formula of a compound of molecular formula C4H8Cl2 in which (a) All the carbons belong to methylene groups (b) None of the carbons belong to methylene groups

What is the hybridization of each carbon in \(\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CHC} \equiv \mathrm{CH}\)? What are the CCC bond angles? Text Transcription: CH_3CH=CHC equiv CH

Of the overlaps between an s and a p orbital as shown in the illustration, one is bonding, one is antibonding, and the third is nonbonding (neither bonding nor antibonding). Which orbital overlap corresponds to which interaction? Why?

Does the overlap of two p orbitals in the fashion shown correspond to a \(\sigma\) bond or to a \(\pi\) bond? Explain. Text Transcription: sigma pi

Aphids secrete an alarm pheromone having the structure shown. What is its molecular formula? Classify each carbon according to its hybridization state.

All the parts of this problem refer to the alkane having the carbon skeleton shown. (a) What is the molecular formula of this alkane? (b) What is its IUPAC name? (c) How many methyl groups are present in this alkane? Methylene groups? Methine groups? (d) How many carbon atoms are primary? Secondary? Tertiary? Quaternary?

Write structural formulas and give the IUPAC names for the nine alkanes that have the molecular formula C7H16.

From among the 18 constitutional isomers of C8H18, write structural formulas, and give the IUPAC names for those that are named as derivatives of (a) Heptane (b) Hexane (c) Pentane (d) Butane

Give the IUPAC name for each of the following compounds: (a) CH3(CH2)25CH3 (b) (CH3)2CHCH2(CH2)14CH3 (c) (CH3CH2)3CCH(CH2CH3)2

Using the method outlined in Section 2.16, give an IUPAC name for each of the following alkyl groups, and classify each one as primary, secondary, or tertiary: (a) CH3(CH2)10CH2? (c) ?C(CH2CH3)3

It has been suggested that the names of alkyl groups be derived from the alkane having the same carbon chain as the alkyl group. The -e ending of that alkane is replaced by -yl, and the chain is numbered from the end that gives the carbon at the point of attachment its lower number. This number immediately precedes the -yl ending and is bracketed by hyphens. Name the C4H9 alkyl groups according to this system.

(a) Given \(\Delta H^{\circ}\) for the reaction \(\mathrm{H}_{2}(g)+\frac{1}{2} \mathrm{O}_{2}(g) \longrightarrow \mathrm{H}_{2} \mathrm{O}(l) \quad \Delta H^{\circ}=-286 \mathrm{~kJ}\) (b) If the heat of combustion of acetylene is 1300 kJ/mol, what is the value of \(\Delta H^{\circ}\) for its hydrogenation to ethylene? To ethane? (c) What is the value of \(\Delta H^{\circ}\) for the hypothetical reaction \(2 \mathrm{H}_{2} \mathrm{C}=\mathrm{CH}_{2}(g) \longrightarrow \mathrm{CH}_{3} \mathrm{CH}_{3}(g)+\mathrm{HC} \equiv \mathrm{CH}(g)\) Text Transcription: Delta H^circ H_2(g)+1/2 O_2(g) longrightarrow H_2O(l) Delta H^circ=-286 kJ 2H_2C=CH_2(g) longrightarrow CH_3CH_3(g)+HC equiv CH(g)

The reaction shown is important in the industrial preparation of dichlorodimethylsilane for eventual conversion to silicone polymers. \(2 \mathrm{CH_3Cl+Si \longrightarrow\left(CH_3\right)_{2} SiCl_2}\) (a) Is carbon oxidized, reduced, or neither in this reaction? (b) On the basis of the molecular model of \(\mathrm{(CH_3)_2SiCl_2}\), deduce the hybridization state of silicon in this compound. What is the principal quantum number n of the silicon s and p orbitals that are hybridized? Text Transcription: 2 \mathrm{CH_3Cl+Si \longrightarrow\left(CH_3\right)_{2} SiCl_2} \mathrm{(CH_3)_2SiCl_2}

Alkanes spontaneously burst into flame in the presence of elemental fluorine. The reaction that takes place between pentane and F2 gives CF4 and HF as the only products. (a) Write a balanced equation for this reaction. (b) Is carbon oxidized, is it reduced, or does it undergo no change in oxidation state in this reaction?

Which atoms in the following reaction undergo changes in their oxidation state? Which atom is oxidized? Which one is reduced? \(2 \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}+2 \mathrm{Na} \longrightarrow 2 \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{ONa}+\mathrm{H}_{2}\) Text Transcription: 2CH_3CH_2OH+2Na longrightarrow 2CH_3CH_2 ONa+H_2

Compound A undergoes the following reactions: (a) Which of the reactions shown require(s) an oxidizing agent? (b) Which of the reactions shown require(s) a reducing agent?

Each of the following reactions will be encountered at some point in this text. Classify each one according to whether the organic reactant is oxidized or reduced in the process. (a) \(\mathrm{CH}_{3} \mathrm{C} \equiv \mathrm{CH}+2 \mathrm{Na}+2 \mathrm{NH}_{3} \longrightarrow \mathrm{CH}_{3} \mathrm{CH}=\mathrm{CH}_{2}+2 \mathrm{NaNH}_{2}\) (c) \(\mathrm{HOCH}_{2} \mathrm{CH}_{2} \mathrm{OH}+\mathrm{HIO}_{4} \longrightarrow 2 \mathrm{H}_{2} \mathrm{C}=\mathrm{O}+\mathrm{HIO}_{3}+\mathrm{H}_{2} \mathrm{O}\) Text Transcription: CH_3C equiv CH+2Na+2NH_3 longrightarrow CH_3CH=CH_2+2NaNH_2 HOCH_2CH_2OH+HIO_4 longrightarrow 2H_2C=O+HIO_3+H_2O

Alkanes occur naturally in places other than petroleum deposits—in insects, for example. The waxy alkanes dispersed in its cuticle help protect an insect from dehydration. Some insects use volatile alkanes to defend themselves or communicate with others of the same species. Alkanes even serve as starting materials that the insect converts to other biologically important substances. The major biosynthetic pathway leading to alkanes is by enzyme-catalyzed decarboxylation (loss of CO2) of fatty acids, compounds of the type CH3(CH2)nCO2H in which n is an even number and the chain has 14 or more carbons. \(\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{n} \mathrm{CO}_{2} \mathrm{H} \longrightarrow \mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{n-1} \mathrm{CH}_{3}+\mathrm{CO}_{2}\) Biochemical conversion of alkanes to other substances normally begins with oxidation. In addition to alkanes, the oxidation of drugs and other substances occurs mainly in the liver and is catalyzed by the enzyme cytochrome P-450. Molecular oxygen and nicotinamide adenine dinucleotide (NAD) are also required. Oxidation by microorganisms has been extensively studied and is often selective for certain kinds of C ? H bonds. The fungus Pseudomonas oleovorans, for example, oxidizes the CH3 groups at the end of the carbon chain of 4-methyloctane faster than the CH3 branch and faster than the CH2 and CH units within the chain. Tridecane [CH3(CH2)11CH3] is a major component of the repellent that the stink bug Piezodorus guildinii releases from its scent glands when attacked. What fatty acid gives tridecane on decarboxylation? A. CH3(CH2)10CO2H B. CH3(CH2)11CO2H C. CH3(CH2)12CO2H D. CH3(CH2)13CO2H Text Transcription: CH_3(CH_2)_nCO_2H longrightarrow CH_3(CH_2)_n-1CH_3+CO_2

Alkanes occur naturally in places other than petroleum deposits—in insects, for example. The waxy alkanes dispersed in its cuticle help protect an insect from dehydration. Some insects use volatile alkanes to defend themselves or communicate with others of the same species. Alkanes even serve as starting materials that the insect converts to other biologically important substances. The major biosynthetic pathway leading to alkanes is by enzyme-catalyzed decarboxylation (loss of CO2) of fatty acids, compounds of the type CH3(CH2)nCO2H in which n is an even number and the chain has 14 or more carbons. \(\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{n} \mathrm{CO}_{2} \mathrm{H} \longrightarrow \mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{n-1} \mathrm{CH}_{3}+\mathrm{CO}_{2}\) Biochemical conversion of alkanes to other substances normally begins with oxidation. In addition to alkanes, the oxidation of drugs and other substances occurs mainly in the liver and is catalyzed by the enzyme cytochrome P-450. Molecular oxygen and nicotinamide adenine dinucleotide (NAD) are also required. Oxidation by microorganisms has been extensively studied and is often selective for certain kinds of C ? H bonds. The fungus Pseudomonas oleovorans, for example, oxidizes the CH3 groups at the end of the carbon chain of 4-methyloctane faster than the CH3 branch and faster than the CH2 and CH units within the chain. Assuming a selectivity analogous to that observed in the microbiological oxidation of 4-methyloctane by Pseudomonas oleovorans, which of the following is expected to give two constitutionally isomeric alcohols on oxidation? A. Heptane B. 3-Methylheptane C. 4-Methylheptane D. 4,4-Dimethylheptane Text Transcription: CH_3(CH_2)_nCO_2H longrightarrow CH_3(CH_2)_n-1CH_3+CO_2

Alkanes occur naturally in places other than petroleum deposits—in insects, for example. The waxy alkanes dispersed in its cuticle help protect an insect from dehydration. Some insects use volatile alkanes to defend themselves or communicate with others of the same species. Alkanes even serve as starting materials that the insect converts to other biologically important substances. The major biosynthetic pathway leading to alkanes is by enzyme-catalyzed decarboxylation (loss of CO2) of fatty acids, compounds of the type CH3(CH2)nCO2H in which n is an even number and the chain has 14 or more carbons. \(\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{n} \mathrm{CO}_{2} \mathrm{H} \longrightarrow \mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{n-1} \mathrm{CH}_{3}+\mathrm{CO}_{2}\) Biochemical conversion of alkanes to other substances normally begins with oxidation. In addition to alkanes, the oxidation of drugs and other substances occurs mainly in the liver and is catalyzed by the enzyme cytochrome P-450. Molecular oxygen and nicotinamide adenine dinucleotide (NAD) are also required. Oxidation by microorganisms has been extensively studied and is often selective for certain kinds of C ? H bonds. The fungus Pseudomonas oleovorans, for example, oxidizes the CH3 groups at the end of the carbon chain of 4-methyloctane faster than the CH3 branch and faster than the CH2 and CH units within the chain. Female German cockroaches convert the alkane shown to a substance that attracts males. Oxidation at C-2 of the alkane gives the sex attractant, which has a molecular formula C31H62O and the same carbon skeleton as the alkane. What is the structure of the sex attractant? Text Transcription: CH_3(CH_2)_nCO_2H longrightarrow CH_3(CH_2)_n-1CH_3+CO_2

Alkanes occur naturally in places other than petroleum deposits—in insects, for example. The waxy alkanes dispersed in its cuticle help protect an insect from dehydration. Some insects use volatile alkanes to defend themselves or communicate with others of the same species. Alkanes even serve as starting materials that the insect converts to other biologically important substances. The major biosynthetic pathway leading to alkanes is by enzyme-catalyzed decarboxylation (loss of CO2) of fatty acids, compounds of the type CH3(CH2)nCO2H in which n is an even number and the chain has 14 or more carbons. \(\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{n} \mathrm{CO}_{2} \mathrm{H} \longrightarrow \mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{n-1} \mathrm{CH}_{3}+\mathrm{CO}_{2}\) Biochemical conversion of alkanes to other substances normally begins with oxidation. In addition to alkanes, the oxidation of drugs and other substances occurs mainly in the liver and is catalyzed by the enzyme cytochrome P-450. Molecular oxygen and nicotinamide adenine dinucleotide (NAD) are also required. Oxidation by microorganisms has been extensively studied and is often selective for certain kinds of C ? H bonds. The fungus Pseudomonas oleovorans, for example, oxidizes the CH3 groups at the end of the carbon chain of 4-methyloctane faster than the CH3 branch and faster than the CH2 and CH units within the chain. Biological oxidation of the hydrocarbon adamantane by the fungus Absidia glauca gives a mixture of two alcohols. Classify the carbon in adamantane that is oxidized in forming the major product. A. Primary B. Secondary C. Tertiary D. Quaternary Text Transcription: CH_3(CH_2)_nCO_2H longrightarrow CH_3(CH_2)_n-1CH_3+CO_2

Describe the bonding in propane according to the orbital hybridization model.

Refer to Table 2.2 as needed to answer the following questions: (a) Beeswax (Figure 2.19) contains 8–9% hentriacontane. Write a condensed structural formula for hentriacontane. (b) Octacosane has been found to be present in a certain fossil plant. Write a condensed structural formula for octacosane. (c) What is the IUPAC name of the alkane described in Problem 2.6 as a component of the cockroach aggregation pheromone?

Phytane is the common name of a naturally occurring alkane produced by the alga Spirogyra and is a constituent of petroleum. The IUPAC name for phytane is 2,6,10,14-tetramethylhexadecane. Write a line formula for phytane. What is its molecular formula?

What is the molecular formula of hopane?

Match the boiling points with the appropriate alkanes. Alkanes: octane, 2-methylheptane, 2,2,3,3-tetramethylbutane, nonane Boiling points (°C, 1 atm): 106, 116, 126, 151

Write a balanced chemical equation for the combustion of cyclohexane.

Using the data in Table 2.3, estimate the heat of combustion of (a) 2-Methylnonane (in kcal/mol) (b) Icosane (in kJ/mol)

Without consulting Table 2.3, arrange the following compounds in order of decreasing heat of combustion: pentane, 2-methylbutane, 2,2-dimethylpropane, hexane.

Pheromones are chemical compounds that animals, especially insects, use to signal others of the same species. Female tiger moths, for example, signify their presence to male moths this way. The sex attractant is a 2-methyl-branched alkane having a molecular weight of 254. What is its structure?

Pristane is an alkane that is present to the extent of about 14% in shark liver oil. Its IUPAC name is 2,6,10,14-tetramethylpentadecane. Write its structural formula.

Write a structural formula for each of the following compounds: (a) 6-Isopropyl-2,3-dimethylnonane (b) 4-tert-Butyl-3-methylheptane (c) 4-Isobutyl-1,1-dimethylcyclohexane (d) sec-Butylcycloheptane (e) Cyclobutylcyclopentane

Write a balanced chemical equation for the combustion of each of the following compounds: (a) Decane (b) Cyclodecane (c) Methylcyclononane (d) Cyclopentylcyclopentane

The heats of combustion of methane and butane are 890 kJ/mol (212.8 kcal/mol) and 2876 kJ/mol (687.4 kcal/mol), respectively. When used as a fuel, would methane or butane generate more heat for the same mass of gas? Which would generate more heat for the same volume of gas?

In each of the following groups of compounds, identify the one with the largest heat of combustion and the one with the smallest. (Try to do this problem without consulting Table 2.3.) (a) Hexane, heptane, octane (b) 2-Methylpropane, pentane, 2-methylbutane (c) 2-Methylbutane, 2-methylpentane, 2,2-dimethylpropane (d) Pentane, 3-methylpentane, 3,3-dimethylpentane (e) Ethylcyclopentane, ethylcyclohexane, ethylcycloheptane

We have seen in this chapter that, among isomeric alkanes, the unbranched isomer is the least stable and has the highest boiling point; the most branched isomer is the most stable and has the lowest boiling point. Does this mean that one alkane boils lower than another because it is more stable? Explain.

Higher octane gasoline typically contains a greater proportion of branched alkanes relative to unbranched ones. Are branched alkanes better fuels because they give off more energy on combustion? Explain.