a. What is the molar mass of an element? b. To two decimal

Explain each of the following in terms of Daltons atomic theory: a. the law of conservation of mass b. the law of definite proportions c. the law of multiple proportions

According to the law of conservation of mass, if element A has an atomic mass of 2 mass units and element B has an atomic mass of 3 mass units, what mass would be expected for compound AB? for compound A2B3?

a. What is an atom? b. What two regions make up all atoms?

Describe at least four properties of electrons that were determined based on the experiments of Thomson and Millikan.

Summarize Rutherfords model of the atom, and explain how he developed this model based on the results of his famous gold-foil experiment.

What number uniquely identifies an element?

a. What are isotopes? b. How are the isotopes of a particular element alike? c. How are they different?

Copy and complete the following table concerning the three isotopes of silicon, Si. (Hint: See Sample Problem A.)

a. What is the atomic number of an element? b. What is the mass number of an isotope? c. In the nuclear symbol for deuterium, 12 H, identify the atomic number and the mass number. 1

What is a nuclide?

Use the periodic table and the information that follows to write the hyphen notation for each isotope described. a. atomic number = 2, mass number = 4 b. atomic number = 8, mass number = 16 c. atomic number = 19, mass number = 39 1

a. What nuclide is used as the standard in the relative scale for atomic masses? b. What is its assigned atomic mass?

What is the atomic mass of an atom if its mass is approximately equal to the following? a. _1 3 that of carbon-12 b. 4.5 times as much as carbon-12 1

a. What is the definition of a mole? b. What is the abbreviation for mole? c. How many particles are in one mole? d. What name is given to the number of particles in a mole? 1

a. What is the molar mass of an element? b. To two decimal places, write the molar masses of carbon, neon, iron, and uranium.

Suppose you have a sample of an element. a. How is the mass in grams of the element converted to amount in moles? b. How is the mass in grams of the element converted to number of atoms? 1

What is the mass in grams of each of the following? (Hint: See Sample Problems B and E.) a. 1.00 mol Li b. 1.00 mol Al c. 1.00 molar mass Ca d. 1.00 molar mass Fe e. 6.022 1023 atoms C f. 6.022 1023 atoms Ag 1

How many moles of atoms are there in each of the following? (Hint: See Sample Problems C and D.) a. 6.022 1023 atoms Ne b. 3.011 1023 atoms Mg c. 3.25 105 g Pb d. 4.50 1012 g O 1

Three isotopes of argon occur in nature 18 36 Ar, 18 38 Ar, and 18 40 Ar. Calculate the average atomic mass of argon to two decimal places, given the following relative atomic masses and abundances of each of the isotopes: argon-36 (35.97 u; 0.337%), argon-38 (37.96 u; 0.063%), and argon-40 (39.96 u; 99.600%). 2

Naturally occurring boron is 80.20% boron-11 (atomic mass = 11.01 u) and 19.80% of some other isotopic form of boron. What must the atomic mass of this second isotope be in order to account for the 10.81 u average atomic mass of boron? (Write the answer to two decimal places.) 2

How many atoms are there in each of the following? a. 1.50 mol Na b. 6.755 mol Pb c. 7.02 g Si

What is the mass in grams of each of the following? a. 3.011 1023 atoms F b. 1.50 1023 atoms Mg c. 4.50 1012 atoms Cl d. 8.42 1018 atoms Br e. 25 atoms W f. 1 atom Au 2

Determine the number of atoms in each of the following: a. 5.40 g B b. 0.250 mol S c. 0.0384 mol K d. 0.025 50 g Pt e. \(1.00\times 10^{-10}\mathrm{\ g\ }\mathrm{Au}\)

Determine the mass in grams of each of the following: a. 3.00 mol Al b. 2.56 1024 atoms Li c. 1.38 mol N d. 4.86 1024 atoms Au e. 6.50 mol Cu f. 2.57 108 mol S g. 1.05 1018 atoms Hg 2

Copy and complete the following table concerning the properties of subatomic particles. 2

a. How is a unified atomic mass unit (u) related to the mass of one carbon-12 atom? b. What is the relative atomic mass of an atom? 2

a. What is the nucleus of an atom? b. Who is credited with the discovery of the atomic nucleus? c. Identify the two kinds of particles that make up the nucleus. 2

How many moles of atoms are there in each of the following? a. 40.1 g Ca b. 11.5 g Na c. 5.87 g Ni d. 150 g S e. 2.65 g Fe f. 0.007 50 g Ag g. 2.25 1025 atoms Zn h. 50 atoms Ba 2

State the law of multiple proportions, and give an example of two compounds that illustrate the law. 3

What is the approximate atomic mass of an atom if its mass is a. 12 times that of carbon-12? b. \(\frac{1}{2} \text { that of carbon- } 12 \text { ? }\)

What is an electron? 3

O rganizing Ideas Using two chemical compounds as an example, describe the difference between the law of definite proportions and the law of multiple proportions. 3

C onstructing Models As described in Section 2, the structure of the atom was determined from observations made in painstaking experimental research. Suppose a series of experiments revealed that when an electric current is passed through gas at low pressure, the surface of the cathode-ray tube opposite the anode glows. In addition, a paddle wheel placed in the tube rolls from the anode toward the cathode when the current is on. a. In which direction do particles pass through the gas? b. What charge do the particles possess? 3

A nalyzing Data Osmium is the element with the greatest density, 22.58 g/cm3. How does the density of osmium compare to the density of a typical nucleus of 2 108 metric tons/cm3? (1 metric ton = 1000 kg) 3

Group 14 of the Elements Handbook (Appendix A) describes the reactions that produce CO and CO2. Review this section to answer the following: a. When a fuel burns, what determines whether CO or CO2 will be produced? b. What happens in the body if hemoglobin picks up CO? c. Why is CO poisoning most likely to occur in homes that are well sealed during cold winter months? 3

Prepare a report on the series of experiments conducted by Sir James Chadwick that led to the discovery of the neutron. 3

Write a report on the contributions of Amedeo Avogadro that led to the determination of the value of Avogadros number. 3

Trace the development of the electron microscope, and cite some of its many uses. 3

The study of atomic structure and the nucleus produced a new field of medicine called nuclear medicine. Describe the use of radioactive tracers to detect and treat diseases. 4

Observe a cathode-ray tube in operation, and write a description of your observations. 4

Performance Assessment Using colored clay, build a model of the nucleus of each of carbons three naturally occurring isotopes: carbon12, carbon13, and carbon14. Specify the number of electrons that would surround each nucleus.

A chemical compound always has the same elements in the same proportions by mass regardless of the source of the compound. This is a statement of A. the law of multiple proportions. B. the law of isotopes. C. the law of definite proportions. D. the law of conservation of mass.

An important result of Rutherfords experiments with gold foil was to establish that A. atoms have mass. B. electrons have a negative charge. C. neutrons are uncharged particles. D. the atom is mostly empty space.

Which subatomic particle has a charge of +1? A. electron B. neutron C. proton D. meson

Which particle has the least mass? A. electron B. neutron C. proton D. All have the same mass.

Cathode rays are composed of A. alpha particles. B. electrons. C. protons. D. neutrons.

The atomic number of an element is the same as the number of A. protons. B. neutrons. C. protons + electrons. D. protons + neutrons.

How many neutrons are present in an atom of tin that has an atomic number of 50 and a mass number of 119? A. 50 B. 69 C. 119 D. 169

What is the mass of 1.50 mol of sodium, Na? A. 0.652 g B. 0.478 g C. 11.0 g D. 34.5 g

How many moles of carbon are in a 28.0 g sample? A. 336 mol B. 72.0 mol C. 2.33 mol D. 0.500 mol 1

Which atom has more neutrons, potassium-40 or argon-40? 1

What is the mass of 1.20 1023 atoms of phosphorus? 1

Cathode rays emitted by a piece of silver and a piece of copper illustrate identical properties. What is the significance of this observation? 1

A student believed that she had discovered a new element and named it mythium. Analysis found it contained two isotopes. The composition of the isotopes was 19.9% of atomic mass 10.013 and 80.1% of atomic mass 11.009. What is the average atomic mass, and do you think mythium was a new element?