# Electrons In Atoms

## Electron Configuration

Electron Configuration: distribution of electrons of an atom or molecule in atomic or molecular orbitals.

• Steps to write an Electron Configuration:
1. Identify how many electrons are in atom.
2. Determine the principal energy level of the atom.
3. You determine the number of sub levels.
4. You can use the table that is to the right.
5. Finally you write the complete electron configuration.

• Example:

Chromium (Cr)- 24

((Ar))- Argon- 18 4s^2 3d^4

## Orbital Notation

Orbital Notation: They use blanks to represent orbitals and arrows to represent electrons.

• Steps to write a Orbital Notation:
1. #1 S level (carrys 2)
2. #2 P level (carrys 6)
3. #3 D Level (carrys 10)
4. #4 F level (carrys 14)

As you are working on your problem, make sure you fill in going right across the table.

Plug the numbers in as you go through the problem, until you reach the element your problem will need.

Chromium: 1s^2 2s^2 2p^6 3s^2 3p^6 4s^1 3d^5 or ((AR)) 4s^1 3d^5