Chemical Names and Formulas

Monatomic Ions Cations Groups 1A, 2A, 3A charges = group number Name: element name “ion” Examples: Na+ sodium ion Mg2+ magnesium ion Al3+ aluminum ion

Common Cations

Monatomic Ions Anions Group A element charges = 8 - group number Name: stem of element name + ide Examples Cl- chloride S2- sulfide O2- oxide N3- nitride

Monatomic Ions Transition Metals (Group B) Charges can’t be predicted from Periodic Table Some are “multivalent” Form more than one ion Name: element name (charge) “ion” “Stock” naming system Use Roman numerals to indicate charge Examples: Stock name Classical name Fe2+ iron (II) ion ferrous ion Fe3+ iron (III) ion ferric ion Cu+ copper (I) ion cuprous ion Cu 2+ copper (II) ion cupric ion

Ionic Charges of Representative Elements

Multivalent Cations

Polyatomic Ions Group of covalently bonded atoms that has a net charge Most are anions Oxyanions contain oxygen End in –ate or –ite SO42- sulfate SO32- sulfite NO3- nitrate NO2- nitrite

Common Anions

Chloroxyanions Polyatomic ions containing oxygen and chlorine Formula Name ClO- hypochlorite ClO2- chlorite ClO3- chlorate ClO4- perchlorate

Polyatomic Ions Some begin with hydrogen H+ + CO32- → HCO3- hydrogen carbonate “bicarbonate” H+ + PO43- → HPO42- hydrogen phosphate “biphosphate” H+ + HPO42- → H2PO4- dihydrogen phosphate

Polyatomic Cations Ammonium Ion NH4 + H+ + :NH3 → NH4 +

9.3 Naming and Writing Formulas for Molecular Compounds Molecular compounds are named using a system of prefixes to indicate the number of each element in the compound Do not use mono- before the first element Example: SF6 sulfur hexafluoride Example N2O4 dinitrogen tetroxide

9.4 Formulas and Names of Acids & Bases Acids are compounds that have one or more ionizable hydrogens General formula HnX HCl (g) + H2O → H3O+ + Cl- (aq)

Common Acids

Names & Formulas for Bases Bases are compounds which produce the hydroxide ion when dissolved in water NaOH (s) → Na+ (aq) + OH- (aq) NH3(g) + H2O → NH4+ (aq) + OH- (aq+ Name as you would ionic compounds

Law of Definite Proportions aka Law of Constant Composition For any compound, the percent composition by mass is always the same A given compound always contains elements in exactly the same proportion by mass E.g. percent composition of water by mass is 11.1% H and 88.9% O regardless of how much or how little there is An ice cube and an iceberg have the same % composition.

Law of Multiple Proportions When two elements form different compounds, the mass of one element combining with the same mass of the other element occur in small whole number ratios H2O2 H2O Mass O 32 g 16 g Mass H 2 g Ratio O:H 16:1 8:1 Ratio O:O 16:8 = 2:1

Flow Chart to Name Chemical Compounds This flowchart will help you name chemical compounds. Begin with the letters Q and R in the general formula Qx Ry. Q and R can be atoms, monatomic ions, or polyatomic ions.