Nomenclature Chapter 9 Chemical Formula n Chemical Formulas

Nomenclature Chapter 9

Chemical Formula n Chemical Formulas tell two things: • Letters = elements • Subscripts = # of atoms of each element Ex. Fe 2 O 3 2 iron atoms & 3 oxygen atoms Ca. CO 3 # elements? # atoms? 3 5 Al 2(SO 4)3 # elements? 3 # atoms? 17

Compounds n Binary compound has 2 elements • Ex. Na. Cl n Ternary compound has 3 elements • Na. NO 3

Review of Ionic Compounds n n n Attraction of (+) and (-) ions. (transfer e-) Metal loses e- (+) Nonmetal gains e- (-) Cation (metal) is written FIRST!! The OVERALL charge of the compound is ZERO.

Binary Ionic Names n n How do you know it’s binary ionic? • metal + nonmetal Rules: 1) Name the first element as it is on the periodic table. 2) Change the ending of the second element to “ide”. 3) Check if the metal is a transition metal. If so, figure out the charge on it and use Roman numerals to show the CHARGE.

Binary Ionic Naming Examples n Na. Br sodium bromide Ca. Cl 2 calcium chloride n Cu 2 O copper (I) oxide n n Fe 2 O 3 iron (III) oxide K 2 S potassium sulfide n Sr 3 P 2 strontium phosphide n n n Co. Br cobalt (I) bromide Mn 3 N manganese (I) nitride

Binary Ionic Naming Exceptions n n Lead (Pb) and Tin (Sn) are not transition metals, but THEY DO NEED ROMAN NUMERALS!! Silver (Ag) and Zinc (Zn) are transition metals, but DO NOT NEED ROMAN NUMERALS! • Sliver is ALWAYS +1 • Zinc is ALWAYS +2

Binary Ionic Formulas n Rules: 1) Write the element symbols. 2) Write the oxidation #s (charges). * If it’s a transition metal, you won’t know the charge – so look at the Roman numeral! 3) Criss-cross the charges down. 4) Simplify the ratio if needed.

Binary Ionic Formula Examples n Write the formula for each name: • copper (II) oxide Cu. O • zinc bromide Zn. Br 2 • copper (I) oxide Cu 2 O • barium chloride Ba. Cl 2 • lead (IV) sulfide Pb. S 2 • calcium nitride Ca 3 N 2 • iron (III) sulfide Fe 2 S 3 • aluminum fluoride Al. F 3 • silver oxide Ag 2 O

Ternary Ionic Compounds n Involve polyatomic ions (group of atoms with an overall charge) n Most polyatomic ions have “ite” or “ate”, meaning oxygen is in it. n Treat the polyatomic ion as a unit and never change its name!! (Don’t use “ide” for it. ) n Put polyatomic ions in parentheses unless the subscript is 1. n NEVER change the subscripts within the polyatomic ion!!

Naming Ternary Ionic Compounds 1) Name the (+) ion. 2) Name the (-) ion (no “ide” if it’s a polyatomic ion!). 3) Use Roman numerals if the metal is a transition metal, lead or tin.

Name Ternary Ionic Examples n Ba. SO 4 barium sulfate n NH 4 OH ammonium hydroxide n Cu(NO 3)2 copper (II) nitrate n Fe 2(CO 3)3 iron (III) carbonate KNO 3 potassium nitrate n Co(OH)2 n cobalt (II) hydroxide

Writing Formulas for Ternary Ionic Compounds n n Use the same criss-cross method as with binary compounds. Remember to use ( ) if the subscript of a polyatomic ion is more than 1! (Watch out for hydroxide!)

Ternary Ionic Formula Examples n Write the formula for each: • aluminum sulfate Al 2(SO 4)3 • ammonium carbonate (NH 4)2 CO 3 • tin (IV) phosphate Sn 3(PO 4)4 • sodium nitrite Na. NO 2 • zinc hydroxide Zn(OH)2 K 2 SO 3 • potassium sulfite

Molecular Compounds n Review of Molecular Compounds: • Involves a sharing of e • Molecules can exist independently • Covalently bonded n How do you know it’s molecular? • All nonmetals!

Naming Molecular Compounds n Use prefixes to indicate the number of atoms. • 1 Exception: Do NOT begin a name with “mono”. n Change the ending of the second element to “ide”. mono 1 hexa 6 di 2 hepta 7 tri 3 octa 8 tetra 4 nona 9 penta 5 deca 10

Naming Molecular Compounds Examples n CO carbon monoxide n CO 2 carbon dioxide n P 2 O 5 diphosphorous pentoxide n P 4 O 10 tetraphosphorous decoxide n N 2 O dinitrogen monoxide

Molecular Formulas n n The prefix tells you what subscript to write. Remember if there is no prefix for the first element, it is “mono”.

Molecular Formula Examples n dinitrogen monoxide N 2 O n sulfur trioxide SO 3 n dinitrogen pentoxide N 2 O 5 n nitrogen trihydride NH 3 n pentaphosphorous decoxide P 5 O 10

When you look at a compound: First – Decided if it’s ionic or molecular!! * Ionic m – nm polyatomic ions * Molecular nm - nm

Acids n What is an acid? • An aqueous solution (in water) of hydrogen compounds n How do you know something is an acid? • It starts with H

Binary Acids n n Binary acid Includes H + one other element. (Ex. HBr) To name: “hydro ic acid”

Naming Binary Acid Examples n Examples: • HCl • HBr • H 2 S hydrochloric acid hydrobromic acid hydrosulfuric acid

Binary Acid Formulas n n Don’t forget to use the criss-cross method! Examples: • hydroiodic acid • hydrofluoric acid • hydrophosphoric acid HI HF H 3 P

Ternary Acids n n Ternary acid H + polyatomic ion. (Ex. HNO 3) If the polyatomic ion’s name ends in “ate”, the acid’s name ends in “ic”. (I “ate” it and it made me s”ic”k. ) n If the polyatomic ion’s name ends in “ite”, the acid’s name ends in “ous”.

Naming Ternary Acids n n n phosphoric acid sulfurous acid sulfuric acid H 2 CO 3 HNO 2 HNO 3 H 3 PO 4 H 2 SO 3 H 2 SO 4 carbonic acid nitrous acid nitric acid

MEMORIZE THESE!! n n Hydrochloric acid – HCl Nitric acid – HNO 3 Sulfuric acid – H 2 SO 4 Acetic acid – HC 2 H 3 O 2 or CH 3 COOH