Ch 05 Molecules and Compounds

5.1 Sugar and Salt 5.2 Compounds Display Constant Composition

A. Every sample of a compound has the same proportions of constituent elements 5.3 Chemical Formulas: How to Represent Compounds

A. Subscripts in formula represent relative number of each type of atom in the molecule B. Order for listing nonmetal atoms: C, P, N, H, S, I, Br, Cl, O, F C. Groups of atoms (polyatomic ions) are set off by parentheses, e.g. Mg(NO3)2

D. Types of Chemical Formulas 1. Empirical 2. Molecular 3. Structural

5.4 A Molecular View of Elements and Compounds A. Atomic elements exist in nature as single atoms B. 7 molecular elements exist as diatomic molecules: H2, N2, O2, F2, Cl2, Br2, I2

C. Molecular compounds are formed between two or more nonmetals D. Ionic compounds are formed between a metal and one or more nonmetals

5.5 Writing Formulas for Ionic Compounds A. Ionic compounds always contain positive and negative ions B. Formula units form neutral compounds

5.6 Nomenclature: Naming Compounds A. Systematic name, e.g. sodium chloride B. Common name, e.g. table salt

5.7 Naming Ionic Compounds A. Type I compounds (formed with monovalent metal ions)

1. Metal in compound forms only one type of ion 2. Most main group metals form type I compounds

B. Naming type I binary ionic compounds 1. Name of cation (metal) + (base name of anion + ide) 2. Example, NaCl is sodium chloride

C. Type II compounds (formed with multivalent metal ions)1. Metal in compound forms more than one type of ion 2. Transition metals usually, but not exclusively, form type II compounds

D. Naming type II binary ionic compounds 1. Name of cation + (charge of cation) + (base name of anion + ide) 2. Charge of cation given in roman numerals 3. FeCl3 is iron (III) chloride

E. Naming ionic compounds containing a polyatomic ion 1. Use the same procedure as ionic compounds 2. Use name of polyatomic ion, not constituent atoms 3. e.g. NaNO3 is sodium nitrate

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5.8 Naming Molecular Compounds A. Formed between 2 or more nonmetals B. (Prefix) name of first element + (prefix) base name of second element + ide C. 1 = mono; 2 = di; 3 = tri; 4 = tetra… D. e.g. N2O is dinitrogen monoxide

5.9 Naming Acids A. Acids are molecular compounds that dissolve in water to form H+ ions B. Binary acids

1. Hydrogen and nonmetal 2. (Hydro + base name of nonmetal + ic) + acid 3. e.g. HCl is hydrochloric acid

C. Oxyacids 1. Hydrogen and polyatomic oxyanion 2. Oxyanions ending with –ate

a. (Base name of oxyanion + ic) + acid b. e.g. HNO3 is nitric acid

3. Oxyanions ending with –ite a. (Base name of oxyanion + ous) + acid b. e.g. HNO2 is nitrous acid

5.10 Nomenclature Summary A. Ionic compounds B. Molecular compounds C. Acids

5.11 Formula Mass: The Mass of a Molecule or Formula Unit A. Formula mass = mass of atom 1 x number of first element in molecule + mass of atom 2 x number of second element + … B. e.g. formula mass of CCl4 = 1 x (12.01 amu) + 4 x (35.45 amu) = 153.81 amu

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