Electrons Core electrons Electrons found in the inner shells Valence electrons Found in the outermost shell of an atom Energy Levels Each layer or shell.

ElectronsCore electrons

Electrons found in the inner shells

Valence electronsFound in the outermost shell of an

atom

Energy LevelsEach layer or shell is considered

one energy level.

An element’s period number indicates the energy level of the element’s valence electrons.

Qwizdom Questions1. Which of the following elements have valence

electrons in Energy Level 1?a. He

b. B

c. Si

2. Which of the following elements have valence electrons in Energy Level 3?

a. He

b. B

c. Si

Electron ConfigurationAn electron’s “address” has four parts

1. Energy level (1-7) Describes how far the electron is from the

nucleus2. Energy sublevel (1s, 2s, 2p, 3s, 3p, 4s, 3d…)

Describes what type of orbital an electron is in

Contains one or more orbitals

3. Orbital (s,p,d,f) Describes the shape of space an electron

occupies Can hold up to two electrons

4. Superscript (1s1, 2p4, 4d8…) Indicates how many electrons are in each

sublevel

# of Orbitals

13

5

7

Filling in Orbital DiagramsFind number of electrons

Start adding electrons starting with first sublevel (1s)

When a sublevel is completely filled, move on to next sublevel following the correct order

Always add up arrow first.

Once all orbitals in a sublevel have an up arrow, then you can add 2nd electron (down arrow)

Energy Level 1 H 1s1 He 1s2

Energy Level 2 Li 1s2 2s1 Be 1s2 2s2

B 1s2 2s2 2p1 C 1s2 2s2 2p2 N 1s2 2s2 2p3