Chem.: Chapter 3
Percent composition
% composition = ______nx MM element______ x100 MM compound (nx = # of atoms of an element in a molecule)
Amount of reactants & products
1) write balanced chem. equation 2) convert quantities of known substances into moles 3) use coefficients in balanced equation to calc. # of moles of desired quantity 4) convert moles of desired quantity into desired units
How to categorize molecules and name compounds?
4 categories: 1) Ionic compounds - ionic bonds (Na+ Cl- --> NaCl) 2) Molecular compounds - covalent bonds (sharing e- --> H2O) 3) Acids and bases 4) Hydrates
Common polyatomic ions
Acetate...........................................C2H3O2 - Carbonate.....................................CO3 2- Bicarbonate..................................HCO3 - Hydroxide......................................OH - Nitrate..............................................NO3 - Nitrite...............................................NO2 - Chromate.......................................CrO4 2- Dichromate...................................Cr2O7 2- Ammonium...................................NH4 + Phosphate.....................................PO4 3- Hypochlorite...............................ClO - Chlorite..........................................Cl2O - Chlorate.........................................ClO3 - Perchlorate...................................ClO4 - Sulfate.............................................SO4 2- Sulfite...............................................SO3 2- Hydrogen Sulfate......................HSO4 - Hydrogen Sulfite........................HSO3 - Peroxide.........................................O2 2- Cyanide...........................................CN - Permanganate.............................MnO4 -
Many polyatomic anions plus H+ are acids
Acid Anion HClO4 (perchloric acid) ClO4 - (perchlorate) HClO3 (chloric acid) ClO3 - (chlorate) HClO2 (chlorus acid) ClO2 - (chlorite) HClO (hypochlorous acid) ClO - (hypochlorite)
Acids of the Halogens
Anion Corresponding Acid F- (Fluoride) HF (hydrofluoric acid) Cl- (Chloride) HCl (hydrochloric acid) Br- (Bromide) HBr (hydrobromic acid) I- (Iodide) HI (hydroiodic acid) CN- (Cyanide) HCN (hydrocyanic acid) S 2- (Sulfide) H2SO4 2- (hydrosulfuric acid)
Transition metal (also ionic -- chemical nomenclature)
FeCl2 ---> 2Cl- -2 so Fe is +2 ---> iron (II) chloride [Ferris] FeCl3 ---> 3Cl- -3 so Fe is +3 ---> iron (III) chloride [Ferric] Cr2S3 ---> 3S 2- -6 so Cr is +3 -> chromium (III) sulfide
Common monoatomic anions and cations
Li+, Na+, Rb+, Cs+, Mg2+, Ca2+, Sr2+, Ba2+, Cr2+/3+, Mn2+/3+, Fe2+/3+, Co2+/3+, Ni2+/3+, Cu+/2+, Ag+, Au+/3+, Zn2+, Cd2+, Hg2+
Naming oxoacids and oxoanions
Oxoacids Removal of H+ Oxoanions per--ic acid --------------------> per--ate ^+[O] Rep. "-ic" acid --------------------> -ate (down)-[O] "-ous" acid --------------------> -ite (down)-[O] hypo--ous acid --------------------> hypo--ite
Base
a substance that yields OH- when dissolved in water NaOH ---> Na+ + OH- Ba(OH)2 ---> Ba2+ + 2OH- NH3 + H2O ---> NH4+ + OH-
Acid
a substance that yields a proton (H+) when dissolved in water
Oxoacid
an acid that contains hydrogen, oxygen and another element ie:) HNO3 (Nitric Acid), H2CO3 (Carbonic Acid), H2SO4 (Sulfuric Acid)
Hydrates
are compounds that have a specific # of water molecules attached to them [NOT A BASE] BaCl2 * 2H2O (Barium chloride dihydrate) LiCl * H2O (Lithium chloride monohydrate) MgSO4 * 7H2O (Magnesium sulfate heptahydrate)
Chemical reactions
balancing chemical reactions: 1) write down correct formulas of reactants & products 2) balance equation one element at a time (for combustion reactions start with C) 3) then move on to H 4) then O 5) verify that # of atoms of each element is balanced
Ionic compounds
consist of cations (+) and anions (-) the sum of the charges of cation(s) and anion(s) = zero
Ionic compounds (chemical nomenclature)
metal + nonmetal (anion); add "ide" to element name BaCl2 -----> Barium Chloride K2O ------> Potassium Oxide Mg(OH)2 -> Magnesium Hydroxide KNO3 ----> Potassium Nitrate KMnO4 --> Potassium Permanganate
Molecular compounds
nonmetals or nonmetals + metalloids for naming: element furthest left in the periodic table is 1st element closest to bottom of group is 1st uses prefixes to indicate # of atoms last element ends in "ide" ie:) HI (Hydrogen Iodide), NF3 (Nitrogen Trifluoride), SO2 (Sulfur Dioxide), N2Cl4 (Dinitrogen Tetrachloride), NO2 (Nitrogen Dioxide), N2O (Dinitrogen Oxide/Nitrous Oxide)
Molecular formula
shows exact number of atoms of each element ie:) C6H12O6
Empirical formula
shows simplest whole number ratio ie:) CH2O
Limiting reagents
what there is not enough of; is based on the ratios
Chemical equations
when balancing chemical equations: 1) adjust stoichiometric coefficients only (coefficients in front of molecules) 2) never change a formula of a compound for the sake of balancing 3) never introduce extraneous formula