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The modern model is also commonly called the electron cloud model. That's because each orbital around the nucleus of the atom resembles a fuzzy cloud around the nucleus, like the ones shown in the Figure below for a helium atom.

1.
Ch. 10 - Atomic Structure

II. Electron Cloud Model

(p.272-274)

Orbital

Energy Levels

Bohr Model Diagrams

II. Electron Cloud Model

(p.272-274)

Orbital

Energy Levels

Bohr Model Diagrams

2.
A. Orbital

Region where there is 90% probability of

finding an electron.

Can’t pinpoint the

location of an

electron.

Density of dots

represents degree of

probability.

Region where there is 90% probability of

finding an electron.

Can’t pinpoint the

location of an

electron.

Density of dots

represents degree of

probability.

3.
A. Orbital

Orbitals have different shapes.

Orbitals have different shapes.

4.
B. Energy Levels

Electrons can only exist at

certain energy levels.

Low energy levels are

close to the nucleus.

Each energy level (n) can

hold 2n2 electrons.

Electrons can only exist at

certain energy levels.

Low energy levels are

close to the nucleus.

Each energy level (n) can

hold 2n2 electrons.

5.
C. Bohr Model Diagrams

Simplified energy levels using Bohr’s

idea of circular orbits.

Can replace with:

e- 3p

Atomic #: 3 4n

e-

Mass: 7

n np n

pn p Maximum e-

# of p: 3 Level 1 2e-

# of e: 3 e- Level 2 8e-

# of n: 4 Level 3 18e-

Level 4 32e-

Simplified energy levels using Bohr’s

idea of circular orbits.

Can replace with:

e- 3p

Atomic #: 3 4n

e-

Mass: 7

n np n

pn p Maximum e-

# of p: 3 Level 1 2e-

# of e: 3 e- Level 2 8e-

# of n: 4 Level 3 18e-

Level 4 32e-

6.
C. Bohr Model Activity

Choose a number between 1 & 18.

Find your element by the atomic number you picked.

Draw a Bohr Model diagram for your element on your marker board.

• Round off the mass listed on the table and subtract the atomic # to find the # of neutrons.

• Abbreviate the # of ‘p’ and ‘n’ in the nucleus.

Have a partner check your drawing.

Repeat with a new element.

Choose a number between 1 & 18.

Find your element by the atomic number you picked.

Draw a Bohr Model diagram for your element on your marker board.

• Round off the mass listed on the table and subtract the atomic # to find the # of neutrons.

• Abbreviate the # of ‘p’ and ‘n’ in the nucleus.

Have a partner check your drawing.

Repeat with a new element.