Marsh’s Emergency Notes for Chemistry

What you must know to proceed!! Locate metals/nonmetals. Identify ionic/covalent bonds. State the standard oxidation state of each family. Name compounds. Write formulas for compounds.

Use the Periodic table: Metals and Nonmetals Left of stairs on periodic table Loose electrons Positive charge Nonmetals Right of stairs on periodic table Gain electrons Negative charge

Identify ionic and covalent compounds. Ionic compounds Metal/nonmetal Cation (+) comes first Anion (-) follows Sum of charges must equal zero. Covalent compounds Nonmetal/nonmetal Element with lowest electronegativity (one on left) comes first. Element with higher electronegativity (one on the right) comes second. Charges “do not matter.” Use prefixes in naming.

Determining oxidation numbers Oxidation numbers are the “charge” of each element. Only matters for ionic compounds. Assigned by family. Sum must equal zero for ionic compounds.

Naming ionic compounds. Metal and nonmetal Name cation (+) [just name the metal] Name the anion (-) [name the nonmetal with –ide ending]

Naming compounds with a polyatomic ion. If the polyatomic ion is positive (ammonium) Name ion (ammonium) then name the anion with –ide ending. If the polyatomic ion is negative. Name cation then name polyatomic ion (do not change ending)

Naming covalent compounds If there is only one of the first element. Name first element Use a prefix for the second element Name second element with –ide ending. If there is more than one of the first element. Use prefix for number of first element Name second element with –ide ending

Prefixes for covalent compounds One – mono Two – di Three – tri Four – tetra Five – penta Six – hexa Seven – hepta Eight – octa Nine – nona Ten - deca

How to name compounds Naming Compounds given formulas. Metal/Nonmetal Ionic Name cation name anion Ex: NaCl (sodium chloride) Naming hydrates: •H2O Name ionic compound Prefix hydrate Ex: CuSO4 •5H2O Copper (II) sulfate penta hydrate Contains polyatomic ion Positive polyatomic ion Name polyatomic ion Name anion Ex: NH4Cl Ammonium chloride Negative polyatomic ion Name cation Name polyatomic ion Ex: Mg(NO3) Magnesium nitrate Nonmetal/Nonmetal Covalent More than one of first element Prefix name first element prefix element ide Ex: P2O5 Diphosphorus pentaoxide One of first element Name first element prefix name elementide Ex: CO2 Carbon dioxide

Writing formulas for compounds List both elements Look on the periodic table and determine metal or nonmetal If first is metal and second is nonmetal then it is ionic. If both are nonmetals then it is covalent. If it contains a polyatomic ion use ionic rules.

Writing formulas for ionic compounds. Elements are listed. Label charges. Reduce charges if possible. Cross charges. Place polyatomic ions in parentheses. You do not write 1’s.

Writing formulas for covalent compounds. Both elements listed. Add subscripts as prefixes describe. Prefixes One – mono Two – di Three – tri Four – tetra Five – penta Six – hexa Seven – hepta Eight – octa Nine – nona Ten - deca