1. Chemical Bonds
8th 4.1 Why Do Atoms Combine?

2. Atoms Combine
Electron Cloud – area of space around a nucleus where an atoms electrons travel
Electrons travel in predictable orbits around the nucleus
The number of protons and electrons will be the same for a neutral atom
The electron cloud will have different energy levels. The electrons in each level will have a different amount of energy.

3. Atoms Combine

4. Atoms Combine

5. Atoms Combine
The closer the electron is to the nucleus, the stronger the attractive force
Electrons on the highest level have the greatest energy
Electron Dot Diagram – chemical symbol and the number of electrons on the outer most shell
Chemical bond – force that holds two elements together.

7. Atoms Combine
Noble Gases – most stable element group, least reactive, inert gases
Halogens – reactive elements in group 17. Ability to gain an electron and form a bond makes it reactive. Fluorine is more reactive than Bromine because their valence electrons are closer to the nucleus.
Alkali Metals – reactive elements in group 1. More reactive as you go down the group.

8. Atoms Combine

9. Lewis Dot Structure Look at the group number
That tells you how many electrons there are on the outer shell.
Place the electrons in a box fashion in a counter clockwise circle.

11. Lewis Dot Structure
1. Look at the group number

12. Lewis Dot Structure
2. That tells you how many electrons there are on the outer shell.

13. Lewis Dot Structure
3. Place the electrons in a box fashion in a counter clockwise circle.