1. 3.1 COMPOUNDS & BONDS When atoms combine together, they form compounds. Compounds are pure substances made of two or more types of atoms joined together by a chemical bond. H 2 O, CO 2, NaCl, MgBr 2 are all compounds Compare with an element: made up of one type of atom. Al, Hg, Br are all elements There are two types of compounds we have: Ionic and Covalent

2. Type I: An ionic compound o A compound made up of (a metal + non-metal ) o One atom loses electrons and one atom gains electrons. o The chemical name of an ionic compound always gives the positive ion first and the negative ion second. What kind of compound would be formed when sodium and chlorine get together?

3. IONIC COMPOUNDS 1)Ionic solids exist as a solid in the form of an ionic lattice. 2)The positive ions attract all of the negative ions, and vice versa. ex: table salt (NaCl): the 1:1 ratio of ions results in a simple square-shaped ionic crystal. See page 78

4. IONIC COMPOUNDS ARE FORMED BETWEEN A METAL (+) AND A NON-METAL (-)

5. POLYATOMIC IONS 1)Polyatomic ions form ionic compounds with other ions. 2)Polyatomic ions are formed by covalent bonds, but bond ionically with other ions to form compounds. Polyatomic ions: PO 4 -3 OH - CO 3 -2 Ex: hydroxide ion (OH - ) will form an ionic bond with lithium (Li + ) to form lithium hydroxide (LiOH). Li + + OH -  LiOH See pages 79 - 80

6. Type II: covalent compounds o A compound made up of (a non-metal + non-metal ) o Atoms share electrons o No gaining or losing electrons. What kind of compound would be formed when oxygen and chlorine get together?

7. SUMMARY Ionic Covalent Remember hydrogen is a non-metal !!!

8. HOMEWORK Worksheet 3.1