Chapter 9 Chemical Formulas and Names

#1 Simple Ionic Compounds Concept: Ionic Formulas are formed from positive and negative ions. Naming: First element (metal) keeps its name. Second element (nonmetal) ends in –ide

Simple Ionic Compounds You already know: Positive ions are formed by metals that lost electrons. Examples: Na 1+ Mg 2+ Al 3+ Negative ions are formed by nonmetals that gained electrons. Examples: Cl 1- O 2- N 3- Si 4-

Simple Ionic Compounds RULE # 1 The overall charge of ionic compounds must equal zero. Examples : Na 1+ Cl 1- Problems: Ca 2+ Br 1- Al 3+ O 2-

# 2 Polyatomic Ion Formulas Concept: Polyatomic ions are groups of atoms that behave as one unit. RULE #2 Treat like single ions in formulas, but must have parentheses when more than one is used in a formula. Examples: Ca 2+ (NO 3 ) 1- 2 (NH 4 ) 1+ 2 O 2- Problem: Ga 3+ (SO 4 ) 2-

Polyatomic Ion Formulas Fact: The polyatomic ions are named based on the atoms that they contain. Those with oxygen and another nonmetal are often name "____ate" with the root of the other nonmetal in the blank. Examples: (NO 3 ) 1- is nitrate (SO 4 ) 2- is sulfate (ClO 3 ) 1- is chlorate

Polyatomic Ion Formulas Fact: Those polyatomic ions with one oxygen less than the "ate" ions are named "----ite" ions. Examples: (NO 2 ) 1- is nitrite (SO 3 ) 2- is sulfite (ClO 2 ) 1- is chlorite

Polyatomic Ion Formulas Some polyatomic ions contain a regular polyatomic ion and one or more hydrogen ions. These ion groups are named hydrogen ____ or bi ______. Examples: H(CO 3 ) 1- is called hydrogen carbonate or bicarbonate H(SO 4 ) 1- is called hydrogen sulfate or bisulfate

#3 Transition Metal Compounds Concept: Transition metals have electrons in d orbitals and can donate different numbers of electrons, thus giving them several different positive charges. RULE: These can be determined from the Roman numeral which is written next to the metal's name. Example: Cu 1+ is Copper I Pb 2+ is Lead II A few transition metal ions only have one charge. Example: Ag 1+ Zn 2+ Cd 2+

#4 - Covalent Compounds In covalent compounds the charges DO NOT have to balance. First element keeps its name. Second element ends in –ide Use Greek prefixes to identify the number of atoms: 1 – Mono 2 – Di 3 – Tri 4 – Tetra 5 – Penta 6 – Hexa 7 – Hepta 8 – Octa 9 – Nona 10 - Deca Example: diposphorous pentoxide P ₂0₅