1. Nomenclature Molecular Compounds

2. Recap Learned about polyatomic ions Learned how to name ionic compounds containing polyatomic ions Learned how to write chemical formulas for ionic compounds containing polyatomic ions

3. Naming Polyatomic Ions Base polyatomic ion sulphateSO 4 2- Add an oxygenpersulphateSO 5 2- Remove an oxygensulphiteSO 3 2- Remove two oxygenhyposulphiteSO 2 2- Add a hydrogenhydrogen sulphateHSO 4 - Replace one oxygen with sulphur thiosulphateS 2 O 3 2-

4. Learning Goals We are learning to… – Name molecular compounds – Write the formula for molecular compounds when given the name

5. Molecules Recall A molecule is a combination of two or more non-metal atoms held together by covalent bonds. A covalent bond is a connection between non- metal atoms where two atoms SHARE a pair of electrons.

6. Diatomic Elements Recall There are seven diatomic elements they are – Hydrogen: H 2 – Nitrogen: N 2 – Oxygen: O 2 – Fluorine: F 2 – Chlorine: Cl 2 – Bromine: Br 2 – Iodine: I 2 These elements only exist as diatomic molecular elements.

8. Naming Binary Molecular Compounds Binary compounds contain two elements. The more electropositive atom is written first and the more electronegative element is written last with an -ide suffix. The names of binary molecular compounds use prefixes to indicate how many atoms of each element are in the compound.

9. Naming Binary Molecular Compounds Number of Atoms PrefixNumber of Atoms Prefix 1mono-6hexa- 2di-7septa- 3tri-8octa- 4tetra-9nona- 5penta-10deca-

10. Naming Binary Molecular Compounds Note: The prefix “mono-” is not used when the first element is only one atom. Prefixes can be shortened when the ending vowel of the prefix "conflicts" with a starting vowel in the compound. ie: CO is carbon monoxide ie: P 2 O 5 is named diphosphorus pentoxide.

11. Naming Binary Molecular Compounds Example: Write the name for N 2 S 3 1.Name the first element 2.Name the second element, which ends with “ide” 3.Add prefixes indicating the numbers of atoms

12. Naming Binary Molecular Compounds Try the following: 1.SO 3 2.P 4 S 10 3.NF 3 4.N 2 O 5.CH 4

13. Writing Formulas for Binary Molecular Compounds Using the name, you can write the formula Write the formula for disulphur decafluoride. 1.Identify the first element, and give its symbol 2.Identify the second element, and give its symbol: 3.Add subscripts to indicate the numbers of atoms. 4.Write the formula

14. Writing Formulas for Binary Molecular Compounds Try the following: 1.sulphur hexabromide 2.carbon tertachloride 3.dinitrogen tetroxide 4.tetraphosphorous decaoxide 5.carbon dioxide

15. Homework Complete the worksheet