Bohr Models and Lewis Dot Structures

Atoms **• Basic unit of matter• Consists of: Electrons, Protons, & Neutrons

+1

+2 +3 +/-4 -3 -2 -1

0

-5

Periodic Table of Elements

= element charges = Valence Electrons

I

II III IV V VI VII

VIII

Element• a pure chemical substance consisting of one type of atom

Atomic Number= Number of Protons = Number of Electrons

Symbol

Name

Mass Number = Number of Protons + Number of Neutrons

Bohr Models

• Proposed by Niels Bohr in 1915• Electrons orbit the nucleus in orbits that have a

set size and energy. • The energy of the orbit is related to its size. • The lowest energy is found in the smallest orbit.

Energy Levels

• When two atoms approach each other, the nuclei do not touch

• Only Electrons are involved in Chemical Reactions

• Electrons feel each other first • MOST IMPORTANT particle for bonding!

• WATCH THIS!

Bohr Models **

• Show just electrons with energy levels• 1st level holds 2• 2nd holds 8• 3rd holds 18 but is stable at 8• 4th holds 32 but is stable at 8

Try Some

• Carbon– Number of p/n/e– Draw Bohr Model

Try Some• Nitrogen

– Number of p/n/e– Draw Bohr Model

– Try some from Worksheet!!!!

Valence Electrons• Electrons that are found on the outer most

energy level. This determines the elements chemical properties

How to draw a Bohr Model?

Lewis Dot Structures• Show only valence electrons • Show only those electrons on outer energy

level