# Bohr Models and Lewis Dot DiagramsPage 1

#### WATCH ALL SLIDES

Slide 1

Bohr Models and Lewis Dot Diagrams

Science 10

Slide 2

Niels Bohr

Slide 3

## Bohr Models…

Niels Bohr explained the structure of the atom in his “Bohr models”. His model of the atom resembles a solar system. He came up with this model in 1913. Here is a typical Bohr model, what can you figure out from it?

Slide 4

Bohr models show the nucleus in the center with the # of Protons (p) and Neutrons (n) in it

Around the nucleus, it shows

the electrons in orbits or shells

Each orbit/shell can only hold a

certain # of electrons and then

it is full.

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## How many e- can each orbit hold?

1st orbit can hold 2 e-

2nd orbit can hold 8 e-

3rd orbit can hold 8 e-

4th orbit can hold 18 e-

You don’t need to know any higher orbits – we won’t be covering higher elements.

You can depict any element in a Bohr model!

Slide 6

Beryllium

4 p+ 5n 4e-

Oxygen

8p+ 8n 8e-

Aluminium

13 p+ 13 e- 14 n

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## So how do we draw a Bohr model of… say…Sodium?

Start with a nucleus, and put in how many protons and neutrons are in sodium (look at your periodic table)

Next place some orbits around it

P:11

N:12

P:11

N:12

Slide 8

Next figure out how many e- are in sodium (look at your periodic table). Place them in dots in the orbits

P:11

N:12

Remember!!

2 max in 1st orbit

8 max in 2nd orbit

8 max in 3rd orbit

18 max in 4th orbit

Sodium has 11 electrons !!

they are the same as the protons

Slide 9

## Draw a Bohr Model for an Argon atom

How many neutrons and protons does it have?

How many electrons does it have?

Slide 10

Practice

Blank Periodic Table

Slide 11

## Valence Electrons

Valence electrons and stability

Which group on the periodic table, do you notice, always has all its valence electron shell full? _

Every element wants to have a full outer shell – because then it is and never has to react.

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