Lecture 11: Molecules and Lewis Dot Structures

Molecular Compounds

Made up of non-metals. Form when non-metal elements share electrons to form covalent bonds.

1

mono

2

di

3

tri

4

tetra

5

penta

6

hexa

7

hepta

8

octa

9

nona

10

deca

When do you use the greek letters for nomenclature?

Only when naming molecular compounds/covalent compounds

Guidlines for molecular nomenclature

• The first element names is the one farthest to the left on the periodic table, or lower in the column

• The number of both elements is shown in the name using the greek prefixes

• Last element named has -ide ending

• Only use mono on the last element

Steps for creating a Lewis structure

1. Calculate the total number of valence electrons

2. Determine which atom will be the central atom in the molecule

3. Arrange atoms symmetrically around the central atom

4. Place bonds/electrons around the atoms until the octet rule is satisfied for each atom

5. Show any charges on the molecule using brackets and place the charge in the upper right corner

Octet rule

An atom must have a full valence shell of 8 electrons. All atoms try their best to gain a full octet

What is the special rule for hydrogen?

Hydrogen’s octet is 2, it can only make 1 bond