Gen. Chemistry 1110-001 Mohseni
Gen. Chemistry 1110-001 Mohseni CHEM 1110 - 01
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This 17 page Class Notes was uploaded by Leah Washburn on Sunday September 18, 2016. The Class Notes belongs to CHEM 1110 - 01 at East Tennessee State University taught by Mohseni in Fall 2016. Since its upload, it has received 23 views. For similar materials see Gen Chem in Chemistry at East Tennessee State University.
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Date Created: 09/18/16
1 Chapter 2 Elements, Compounds, and The Periodic Table Objectives: Periodic Table Chemical Equations Writing and naming chemical compounds Periodic Table: The rows in the table are called periods. The columns are called groups or families. The table is arranged in order of increasing atomic number (# e's, or # p's). The elements in a group have the same chemical properties. For example, Li, Na, and K react with water and release hydrogen gas. Ten elements in the center (Groups IIIB, IIB) are referred to as transition elements. Elements in Group IA are called alkali metals. Elements in Group IIA are called alkali earth metals. Elements in Group VIIA are called halogens. 2 Elements in Group VIIIA are called noble gases. They are unreactive. Metals, Nonmetals, Metalloids: Draw a diagonal line starting to the left of boron. Elements on the left side are metals except for Ge, Sb, and Po. The elements immediately adjacent to the right of the diagonal are metalloids. Ge, Sb, and Po are metalloids as well. The rest are considered nonmetals. Problem: Classify the following elements as metals (M), nonmetals(NM), metalloids(ML): Kr NM Po ML Zn M Al M Te ML C NM Ca M Molecules and Ions: A molecule is formed when two or more atoms combine. Problem: How many different kinds of atoms are there in one molecule of water? 2 3 A molecule is a definite group of atoms that are chemically bonded together. The atoms are held by strong force of covalent bonds in a molecule. The atoms forming molecule are usually nonmetals. Ex: HI is a molecule formed from hydrogen (H) and iodine (I) atoms. The dashed line between the two atoms refers to a covalent bond. Note that some elements exist in the form of molecules. Note that all elements ending in –gen and all elements ending in –ine form diatomic molecules. Ions: An ion is an electrically charged particle obtained from an atom or molecule by adding or removing e’s. The atoms are capable of losing or gaining electrons. When one or more electron(s) are lost or gained, an ion is formed. The ions always carry charges. The charge on the ion is written as the superscript following the symbol for that element. Calcium (Ca) with an atomic number of 20 has 20 electrons, 20 protons, and 20 neutrons. 4 Ca 20 e 20 x (1) = 20 20 p 20 x (+1)= +20 So the total charge is (+20 + 20) = 0 Problem: What is the charge of Ca ion when losses two electrons? +2 Problem: Write down the ionic symbol for the following cases: Chlorine gaining one electron. Cl barium losing two electrons. +2 Ba oxygen gaining two electrons. 2 O iron losing two electrons. Fe2+ iron losing three electron. 5 Fe 3+ IMPORTANT: Metals tend to lose e's forming positive ions. These positively charged ions are called cations. Nonmetals will gain e's forming negative ions called anions. Elements in Group 1 form +1 ions. Elements in Group 2 form +2 ions. Elements in Group VIIA could form 1 ions. Transition metals could form more than one ion. Writing Chemical Equations: representation of a chemical rxn in terms of chemical formulas Na (s)+ 2 O NaOH (aq) + H (2 What are the reactants or starting materials? Na H 2 What are the products? NaOH H2 2H 2 2aq) 2H 2 (l) + O 2g) Do you see anything wrong with the above rxn? Balancing Chemical Equations: 6 CH 4 + 2 O 2 CO + 2 H O 2 C 4 8+ 6O 2 4CO + 22H O 2 4H P3 3 3H PO 3+ 4PH 3 Ca + 2H O Ca(OH) (g) + H 2 2 2 Fe 2SO ) 4 3 6NH + 3H O 2 2Fe(OH) + 3(NH )3 SO 4 2 4 Ions: 3+ 2 2 monoatomic, e.x. Fe , S , O 2 Ployatomic, e.x. OH, CN , SO 4 Chemical Formulas: It shows the composition of molecules and ionic compounds, as well as the ratio between the elements. Atoms that are close to a noble gas (Group VIIIA) in the Periodic Table tend to form ions that contain the same number of electrons as the neighboring noble gas atom. 7 Molecular Formulas Show exact number of atoms of each element in a molecule. Ex. Water, sulfuric acid, hydrochloric acid, oxygen gas, nitrogen gas Organic Compounds: Contain C combined with H, O, N Empirical Formulas Show the elements involved and the simplest wholenumber ratio of their atoms. H 2 2 N 2 4 HO NH 2 Problem: Find the empirical formula for glucose (C H6O 12 6 CH O 2 How to write formulas for ionic compounds: 8 The symbol for the cation (metal?) comes first followed by the symbol for anion. The charge on the cation becomes the subscript for the anion, and the charge on the anion becomes the subscript for the cation. No + or sings. Ex. Sodium chloride Example: Sodium and oxygen gas can react to form a compound called sodium oxide. What is the chemical formula for the product? Na 2 Problem: Write the correct chemical formulas for the reaction of: magnesium w/ sulfur MgS bromine w/ calcium CaBr 2 lead w/ chlorine PbCl 2 silver w/ fluorine AgF hydrogen w/ oxygen H2O 9 hydrogen w/ iodine HI aluminum w/ oxygen Al 2 Polyatomic Ions: + NH 4 ammonium charge +1 OH hydroxide charge 1 NO 3 nitrate charge 1 ClO 3 chlorate charge 1 CO 3 carbonate charge 2 SO 4 sulfate charge 2 PO phosphate charge 3 4 10 HPO 4 hydrogen phosphate charge 2 ClO 4 perchlorate charge 1 MnO 4 permanganate charge 1 CN Cyanide charge 1 Naming Compounds: Figure 2.32 Page 97 Ionic Compounds: these compounds are made up of cations and anoins. Ionic compounds are mainly between a metal and a nonmetal element. The name of the metal comes first followed by the name of nonmetalic element. We need to add the suffix ide to the stem of the nonmetal name. Ex. Br bromine Cl chlorine Problem: Name the following compounds: LiCN Lithium Cyanide NaOH Sodium Hydroxide 11 KOH Potassium Hydroxide AlN Aluminium Nitride The metals forming more than one type of cation have to carry the number of charges for naming. Ex. CuCl Copper I Chloride FeBr 2Iron II Bromide FeCl 3Iron III Chloride 2+ Mn Mn(II) 3+ Mn Mn(III) 4+ Mn Mn(IV) Problem: Name the following compounds: Mn(OH) 2 Manganese II Hydroxide MnCl 4 Manganese IV Chloride 12 Mn O2 3 Manganese III Oxide Questions: What is the charge on Fe in FeI 3 3+ What is the formula for Copper(I) bromide? CuBr What is the name for CuBr ? 2 Copper II Bromide Write a chemical formula for aluminum sulfate . Al 2SO ) 4 3 Binary Molecular Compounds: If it is made up of two different nonmetals, first word is the name of the first element. Greek prefixes are used for number of atoms of that element. 13 Then name the second nonmetal with Greek prefix if necessary. Greek Prefixes Number Prefix 1 mono 2 di 3 tri 4 tetra 5 penta 6 hexa 7 hepta 8 octo Ex. CO is Carbon Monoxide CO 2is Carbon Dioxide Co is Cobalt Acids: + Acids are the substances that produce hydrogen ion (H ) when dissolving in water. The formula indicates presence of one or more hydrogen(s). Ex. HCl Hydrochloric Acid 14 HBr Hydrogen Bromide HI Hydro iodic Acid The HCl (g) is called hydrogen chloride but when dissolved in water it is an acid because HCl breaks down to H and Cl. The HCl in water is called hyrdochloric acid. When anions whose names end in "ide" form acids, you need to add both "hydro" and "ic" as prefix and suffix, respectively. Important Some acids contain oxygen, hydrogen, and other elements. They are called OXOACIDS; means acids containing oxygen. Memorize the followings: HNO 3 Nitric acid H 2O 4 Sulfuric acid H 2O 3 Sulfurous acid H 3O 4 Phosphoric acid H 3O 3 Phosphorus acid H 2O 3 Carbonic acid Sometimes, two or more oxoacids have different number of oxygen but same central atom. 15 Memorize more: HClO 4 perchloric acid HClO 3 chloric acid HClO 2 chlorous acid HClO hypochlorous acid Naming polyatomic oxoions (oxoacids H's) with the central atom not in its highest oxidation state. Group VIA: Prefix stem ending Highest state per ox ate One less O “root” ox ite Two less O hypo ox ite Ex: prefix stem ending 2 Highest State SO 4 per sulf ate 16 One less O, SO 3 2 “root” sulf ite Two less O, SO 22 hypo sulf ite Group VIIA: Highest state per brom ate One less O “root” brom ate Two less O “root” brom ite Three less O hypo brom ite Ex: ClO 4 per chlor ate ClO 3 “root” chlor ate 17 ClO 2 “root” chlor ite ClO hypo chlor ite Hydrates: A hydrate is a compound containing water molecules weakly bound in its crystal. CuSO 4s called Copper II Sulfate CuSO 45H O2is called Copper II Sulfate Pentahydrate Brownian motion: A phenomenon that points to the existence of molecules. When very small particles such as tiny grains of pollen are suspended in a liquid and observed under a microscope, the tiny particles are seen to be consistently jumping and jiggling about. It appears that they are knocked back and forth by collisions with something. Imagine “something” is the molecules of the liquid.