Topic 3, Naming Compounds, Formulas, & Equations
Topic 3, Naming Compounds, Formulas, & Equations
(Key concepts)

Naming Compounds:
Binary (composed of two different elements)
*Metal + Nonmetal: Write and name metal first followed by nonmetal; drop ending of nonmetal and add ide; NaCl is sodium chloride
*Nonmetal + Nonmetal: Write and name the less electronegative element first followed by the more electronegative element; drop the ending of the second element and add ide; indicate numbers of atoms present
(mon = 1; di = 2; tri = 3; tetra = 4);
Examples: CO is carbon monoxide and CO2 is carbon dioxide; CCl4 is carbon tetrachloride Others:
(Polyatomic ion formulas, names, and charges are listed on Table E)
*Metal + a - Polyatomic ion:
NaNO3 is sodium nitrate
*+ Poly + a nonmetal:  NH4Cl is ammonium chloride
*+ Poly + a - Poly: NH4NO3 is ammonium nitrate Empirical formulas:
*Lowest terms; reduced
*C3H6 reduces to CH2
*C6H12O6 reduces to CH2O
*Sometimes the molecular and empirical formula are the same; H2O, CH4

Counting atoms:
*Subscript: 2 is the subscript in H2O
*Coefficient:  3 is the coefficient in 3H2O
*In 3H2O, there are 6 atoms of H and 3 atoms of O
*In 3Mg(OH)2, there are 3 atoms of Mg, 6 atoms of O, and 6 atoms of H

Oxidation numbers (states):
*Listed (selected) on the periodic table
*Represent what appears to happen to e-

*Used to write formulas
*Examples:
*HCl: H is +1 and Cl is -1; add up to 0 in HCl
*MgCl2: Mg is +2, each Cl is -1, therefore need 2 Cls to add up to 0
*Al(OH)3:  Al is +3 and OH is -1 Stock system:
*Used to indicate the oxidation number in a compound containing metals with more than one + oxidation state
Examples:
*Iron (II) Oxide is FeO
*Iron (I) oxide is Fe2O

Types of reactions:
*Synthesis:  A + B --> AB
*Decomposition:  AB --> A + B
*Single replacement:  A + BC --> B + AC
*Double replacement:  AB + CD -->  AD  + CB

Exothermic and Endothermic reactions:
*Energy is released during exothermic reactions;
A + B -->  AB  + energy *Energy is absorbed during endothermic reactions; AB + energy -->  A + B Equations:
*Reactants --> Products
*During chemical reactions, bonds are broken, atoms are rearrange, new bonds are made.
*Matter (mass, atoms) can not be created or destroyed.  If 6 carbon atoms enter a reaction, 6 must also exit a reaction.  Therefore, equations must be balanced.
*H2 + O2 -->  H2O is not balanced.  There are 2 Hs on both sides of the arrow, but 2 Os on the left and only 1 on the right.  Matter, O, appears to have been destroyed.
*2H2 + O2 -->  2H2O is balanced. There are 4 Hs and 2 Os on both sides of the arrow.  Matter was conserved.