Atoms, Molecules & Ions Dr. Casagrande: AP Chemistry Naming - - PowerPoint PPT Presentation

Atoms, Molecules & Ions

• Dr. Casagrande: AP Chemistry

Naming ionic compounds

Has metal and nonmetal or polyatomic ion Monatomic cations (metals) named as element Roman numerals indicate charge for all metals other than Group 1, 2, Al3+, Cd2+, Zn2+, Ag+

Obtain charge from formula & anion charge

Monatomic anions (nonmetals) take element name with –ide ending Don’t need to memorize polyatomic ions Most polyatomic anions end in –ate or –ite Most common: NO3–, SO42–, CO32–, PO43– Polyatomic cations: NH4+ (ammonium) & Hg22+ [mercury (I)] e.g. NaI: sodium iodide
 Fe2(SO4)3: iron(III) sulfate (iron has a +3 charge since sulfate is a –2)

Formulas of Ionic Compounds

Write symbol/formula of cation from periodic table or polyatomic ion chart Write symbol/formula of anion If ends in –ide usually monatomic ion If ends in –ate or –ite must be polyatomic ion Write charges on ions, then criss-cross to make neutral Enclose polyatomic ions in parens if more than one in formula Erase charges or rewrite without charges e.g. calcium hydroxide: Ca2+ OH1– Ca(OH)2
 nickel(III) bromide: Ni3+ Br1– NiBr3

Names & Formulas of Molecular Compounds

2 non-metals First element named, second element has –ide ending Usually arranged with higher electronegativity element 2nd Use Greek prefixes to indicate number of each atom: mono, di, tri, tetra, penta, hexa, hepta, octa, nona, deca e.g. N2O5: dinitrogen pentoxide
 CO: carbon monoxide (note: only use “mono” for second element)
 sulfur hexafluoride: SF6
 tetraphosphorous decoxide: P4O10

Naming & Formulas of Acids

Start with H+, paired with anion Need 1 H+ for each negative charge Binary acids (no O) use hydro– prefix, –ic suffix: HCl: hydrochloric acid, HCN: hydrocyanic acid Hydrosulfuric acid: H2S; Hydroiodic acid: HI For oxoacids, polyatomic anion determines name: 
 –ate ➯ –ic (no hydro), –ite ➯ –ous: HClO (HOCl): hypochlorite ➯ hypochlorous acid HNO3 (HONO2): nitrate ➯ nitric acid Phosphorous acid: H1+ PO33– ➯ H3PO3 Perbromic acid: H1+ BrO41– ➯ HBrO4

Hydrates

Ionic compounds with H2O molecules bound within lattice Use Greek prefixes to indicate number of H2O molecules: CaCl2 · 2 H2O: calcium chloride dihydrate CuSO4 · 5 H2O: copper(II) sulfate pentahydrate