MODERN ATOMIC THEORY

Chapter 4 Section 3

Modern Atomic Theory

Electrons can be found only in certain energy levels, not between levels

The location of electrons cannot be predicted precisely

Electrons

Electrons act like waves waves on a vibrating string

They are not on one definite path

Exact location cannot be determined

Orbital

A region in an atom where there is high probability of finding electrons.

4 types of orbitals

S, P,D,F

Energy Level

Number of orbitals by type

Total Number of orbitals

Total number of Electrons

S P D f

X 2

1 1 1=1 2

2 1 3 1+3=4 8

3 1 3 5 1+3+5=9 18

4 1 3 5 7 1+3+5+7=16

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Energy Levels

Many possible energy levels

The number of energy levels that are filled depends on the number of electrons

Valence Electrons

Electrons in the outer energy level of an atom

They determine the chemical properties of an atom

Electron Transitions

Electrons jump between energy levels when an atom gains or loses energy

Photon

A unit or quantum of light

Photons of light have different energies

When an electron absorbs a photon it gains energy

Atoms absorb or emit light at certain wavelengths

Energy of a photon is related to the wavelength of the light.

Each element emits a different wavelength due to its atomic structure