1. formula unit Covalent Bonding: Learning to Cooperate

2. describe a covalent bond state the differences covalent and ionic bonds explain the term molecule describe a diatomic molecule Key Words covalent compound covalent bond diatomic molecule

3. Covalent Compound: Contains 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

4. Fluorine atom: 9 p + 9 e - F Fluorine atom: 9 p + 9 e - F F 2 covalent compound

5. H H Water H 2 O 1p 8p 1p O A molecule has different properties than the atoms from which it is formed

6. Methane CH 4 C H H H H

7. Ammonia NH 3 N H H H

8. O Atoms can share one pair of electrons, or two or three pairs. S In the end – electrons must be arranged so that each atom has 8 electrons around it.

9. Diatomic Elements Forming a Covalent Bond with Yourself

10. No new substance is formed - the covalent bond forms a molecule of only one type of atom. Diatomic elements are unstable as single atoms. H H They form covalent bonds with a same atom to make a stable molecule. H2H2 molecule

11. I H N Br O Cl F ave o ight r ever riends Diatomic Elements: 2 2 2 2 2 2 2

12. ElementSymbolDiatomic Molecule IodineII 2 (solid) HydrogenHH 2 (gas) NitrogenNN 2 (gas) BromineBrBr 2 (liquid) OxygenOO 2 (gas) ChlorineClCl 2 (gas) FluorineFF 2 (gas)

13. OO O2O2 molecule (double bond) F2F2 molecule (single bond) FF

14. Covalent Bonding: Naming and Writing

15. Same – covalent compounds are also named using the “ide” ending for last non-metal. Different – covalent naming uses prefixes before the name of each element. Prefixes show the number of atoms of that element in the formula for the molecule. Diatomic Elements 2

16. PrefixNumber of Atoms mono 1 di 2 tri 3 tetra 4 penta 5 hexa 6

17. 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

18. Prefix Number of Atoms mono1 di2 tri3 tetra4 penta5 hexa6 sulfur oxide SO mono 3 tri sulfur trioxide carbon bromide C Br tri 36 hexa tricarbon hexabromide

19. 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

20. nitrogen iodide N IN I 3 tri Prefix Number of Atoms mono1 di2 tri3 tetra4 penta5 hexa6 carbon oxide CO 2 di silicon sulfide Si S di 2 4 tetra

22. **Always identify a compound as ionic (m + nm) or covalent (nm + nm) before doing anything. Prefixes are used in naming covalent compounds ONLY. Criss-crossing is only used in ionic compounds. DO NOT reduce covalent compounds. IMPORTANT POINTS:

23. sulfur chlorideberyllium chloride BeCl 2 Be SCl mono 2 di metal non-metal ioniccovalent Cl +2 - - SCl