1. Atomic Structure and Chemical Bonds
Why do atoms combine?
Chapter 6 Section 1

2. Atomic Structure
The center of every atom is a nucleus that contains protons and neutrons
The electron cloud- the area of space surrounding the nucleus where the electrons are found
We cannot calculate the exact position of any one electron, but we can predict where they are likely to be

3. Element Structure
The number of protons and electrons is always the same for a neutral atom of an element
Example: A neutral atom of Helium has 2 protons and 2 electrons

4. Electron Arrangement
All electrons are found somewhere in the electron cloud, however some are closer to the nucleus than others
Energy levels are different areas for an electron in an atom, each level represents a different amount of energy
The farther the energy level is from the nucleus the more electrons it can hold

5. Energy Steps
Electrons in the level closest to the nucleus have the lowest amount of energy and are said to be in energy level one
Electrons farthest from the nucleus have the highest amount of energy and the easiest to remove
Removing electrons that are closer to the nucleus take more energy than removing electrons farther from the nucleus

6. Energy Steps Energy level 1—holds 2 electrons
A formula for to find how many electrons each energy level can hold is
2n² where n is the number of the energy level

7. Periodic Table and Energy Levels
You can use the periodic table to find the number of electrons, by using the atomic number, which is the same as the number of protons

8. Electron Configurations
You can see in the periodic table that the number of electrons in a neutral atom of the element increases by one from left to right across a period
If you look at period one it contains Hydrogen and Helium. Energy level one can hold up to 2 electrons, so Helium fills the first energy level, which means that it is a stable atom.
Stable atoms do not like to combine with other atoms
Each period ends with a stable element or a full configuration

9. Here is a thought!
What does the electron energy level diagram look like for bromine and calcium?
What happens to the outer electrons when these two elements combine to form calcium bromide?
Calcium Bromine

10. Element Families
Last chapter we learned a lot about each element family.
Look at the outer energy levels, notice that the energy levels for noble gases are completely filled, this is why they are the most stable elements.
The alkali metals, which we already learned are the most reactive only have one electron in their outer shell, which makes them very reactive.

11. Electron Dot Diagrams
An electron dot diagram is the symbol for the element surrounded by as many dots as there are electrons in its outer energy level.
We only use the outer energy electrons because they are the only electrons that determine how the element reacts.
What forms when atoms are joined by a chemical bond?

12. What is this good for
We use the electron dot diagram to decide how elements bond and where the chemical bond will form.
Atoms always bond with other atoms in a way so their outer energy level is full.