Chemical Formula and Naming

Octet rule: atoms react to acquire a full outer shell: Give away an e - to another atom. Take an e - from another atom. Share an e - with another atom. Ionic bond Covalent bond An ION is an atom that has lost or gained an electron. Lose e - – positive ion OR cation. (metals) Gain e - – negative ion OR anion. (nonmetals)

Writing Rule 1: Write the symbol of the metallic element first. Be Cl Rule 2: Place the combining capacity of one element as a subscript of the other element. Beryllium combines with Chlorine

Rule 3: Leave subscripts with a value of 1 out. Be Cl 21 Two Naming rules: 1.Write the full name of the metal ion first. 2.Name the non-metal ion dropping the last part of the name and adding the suffix “ide”. berylliumchloride

Rule 4: Reduce the subscripts if possible. Mg S Magnesium combines with Sulfur Mg S magnesiumsulphide

Transition metals can give away different numbers of electrons. To avoid confusion: Brackets are used to show how many electrons the Transition metal is giving away.

Iron (III) chloride Iron (II) chloride Fe Cl FeCl 2 Fe Cl FeCl 3

Write the name of the ionic compound: PbO lead oxide(IV) +4-2

Covalent Compound: Contain two or more NON-METAL atoms. Formed by SHARING valence electrons to fill outer shell – octet rule.  A molecule is the smallest unit of a covalent compound. Non-metal + Non-metal = covalent bonding

PrefixNumber of Atoms mono1 di2 tri3 tetra4 penta5 hexa6 hepta7 octa8 nona9 deca10

Step 1: first non-metal is named with a prefix to show the number of atoms. We do not use “mono” for the first non-metal. nitrogen oxide N O Step 2: second non-metal is named with a prefix AND with the “ide” ending. di 24 tetra dinitrogen tetroxide Prefix Number of Atoms mono1 di2 tri3 tetra4 penta5 hexa6

Writing formulas Step 1: Write the symbol of each element. Step 2: Use a subscript to show the number of each type of atom given by the prefix. Do not reduce covalent formulas. phosphorus oxide P O di 2 5 penta Prefix Number of Atoms mono1 di2 tri3 tetra4 penta5 hexa6

Polyatomic Ions (poly = many) Groups of covalently bonded atoms that act as ions. Polyatomic ions function as one unit with one charge – lose or gain electrons. DO NOT change the subscripts of polyatomic ions. Al(C 2 H 3 O 2 ) 3

Write the name of the ionic compound: Al(C 2 H 3 O 2 ) Al C 2 H 3 O aluminum acetate

nickel (II) nitrate MgSO 4 potassium permanganate Fe(OH) 3 calcium acetate Ag 2 CrO 4 lead (II) carbonate Sn(SO 4 ) 2 sodium hydrogen phosphate NH 4 NO 2 1.Ni(NO 3 ) 2 2.magnesium sulfate 3.KMnO 4 4.iron (III) hydroxide 5.Ca(C 2 H 3 O 2 ) 2 6.silver chromate 7.PbCO 3 8.tin (IV) sulfate 9.Na 2 HPO 4 10.ammonium nitrite