Electron Configuration and Energy Levels:

Ground state: All the electrons in an atom have the

lowest possible energies Most stable electron configuration

Example: Sodium (Na)Example: Sodium (Na) Pictures show all the Pictures show all the

electrons in a sodium atom electrons in a sodium atom Neutral Sodium has 11 Neutral Sodium has 11

protons (p+) and 11 protons (p+) and 11 electrons (e-)electrons (e-)

First layer fills up with 2 First layer fills up with 2 electrons - 9 left over electrons - 9 left over

Next layer fills up with 8 Next layer fills up with 8 electrons - 1 left over electrons - 1 left over

Last electron is all alone in Last electron is all alone in the next layer the next layer

All of the Electron ShellsAll of the Electron Shells

Analogy: staircase. •Can stand on a stair, not between stairs. •It takes energy to raise from a lower stair to a higher stair. •In the same way, electrons can be in lower or higher energy level but not in between.

Electron Energy Levels:

Electrons can not exist between energy Electrons can not exist between energy levels (shells).levels (shells).

They must jump from one level to the next.They must jump from one level to the next.Energy must be added to atom for Energy must be added to atom for

electron to jump to higher energy level.electron to jump to higher energy level.When electron falls backWhen electron falls back to it’s original to it’s original

state, state, energy is released as specific energy is released as specific wavelength of light.wavelength of light.

Electron Configuration and Energy Levels:

Electron at Ground State.

Add energy in the form of heat.

Electrons become excited, and

move to a higher energy level.

Electron returns

to Ground State

Energy is given off as light.

Emission SpectrumEmission Spectrum Each elementEach element has different “energy staircase” , has different “energy staircase” ,

i.e. i.e. unique series of electron energy stepsunique series of electron energy steps.. To move between steps, To move between steps, electrons absorb or electrons absorb or

emit specific amounts of energy,emit specific amounts of energy, Amount of energy corresponds to specific Amount of energy corresponds to specific

wavelengths (colors) of lightwavelengths (colors) of light. . Emission spectrum: unique series of energy Emission spectrum: unique series of energy

differences (i.e. colors) differences (i.e. colors) between steps allows between steps allows identification of elements identification of elements by light energy they by light energy they emit.emit.

Red . Orange . Yellow . Green . Blue . Indigo . Violet

Long wavelength

Short wavelength

Less Energy

Greater Energy

Red

Orange

Yellow

Green

Blue

Indigo

Violet

Flame TestFlame Test

We will place samples of elements into a We will place samples of elements into a flame. flame.

This will add energy to the atom in the This will add energy to the atom in the form of heat.form of heat.

The electrons will them become excited, The electrons will them become excited, and jump to a higher energy level.and jump to a higher energy level.

Flame Test Flame Test

Then the electrons will return to their Then the electrons will return to their original ground state.original ground state.

As they return to a lower energy level, the As they return to a lower energy level, the energy will be given off in the form of light.energy will be given off in the form of light.

Different elements will have different flame Different elements will have different flame colors because of their unique electrons.colors because of their unique electrons.

This characteristic spectrum can be used This characteristic spectrum can be used to identify an element. to identify an element.