Ch. 7 – Chemical Formulas & Chemical Compounds

1. Ch. 7 – Chemical Formulas & Chemical Compounds • This chapter introduces methods for naming, writing, and identifying chemical compounds. • Examples: CaCO3 – limestone, NaOH – lye, HCl – muriatic acid, NaCl – table salt, C6H12O6 – glucose, C12H22 O11 – sucrose.

2. Al2O3 – How many Al? How many O? • Al2(SO4)3 – How many Al,S, & O? • Monatomic ions form from a single atom • Ex. Na+, Cl -, Mg2+ • Cation- positive • Anion – Negative • Binary compounds are composed of 2 different elements. • Ex. Sodium chloride, Barium sulfide

3. Naming Compounds • New system of nomenclature (Stock System) • Write the 1st element’s name  usually positive • Write the 2nd element’s name – use the suffix –ide • If the 1st element is a transition element (3-12) or an element with more than one charge, you need to place a roman numeral behind it to show its charge. • Be able to recognize if some of the elements in the compounds are polyatomic ions. • EXAMPLES: KI, Sr2F, CuCl, ZnS, Fe2O3

4. Old System of Nomenclature • Instead of using roman numerals for elements with more than one charge, you use the following: • ous for the suffix of the element if it’s the lower charge. • ic for the suffix of the element if it’s the higher charge. • Pg. 20

5. Nomenclature is the method of naming chemical compounds. • Oxyanions are polyatomic ions that contain oxygens • Ex. OH-, SO4- • Numerical Prefixes (Table 7-3) – pg. 212 • Ex. 2 –di, 3 – tri, 4 – tetra, 5 - pent • Binary compounds with prefixes: • NO2 – nitrogen dioxide • N2O5 - ?

6. Binary Acids & Oxyacids • Binary acids are solutions of binary compounds with hydrogen at the beginning. • Ex. HCl, HF, HBr • Oxyacids contain H,O, and a third element. • Ex. HNO3, H2CO3, H2SO4, H3PO4