The Bohr Atom

The Bohr Theory Evidence: An object at a high temperature emits light. Light and other radiation is emitted from all hot matter.

Light travels in photons. Each photon has a different wavelength, energy and colour.

You get a rainbow of all of the colours in white light. Separate the white light into colours with a diffraction grating or prism

Do the same with various atoms and you get unique emission spectra. These are unique sets of lines for each element. Each line represents a photon of light emitted from the excited atom.

The Bohr Atom 1920 Evidence- 1.Emission Spectra of atoms- this is the light given off of hot excited atoms. hydrogen neon helium

To explain emission spectra, Bohr proposed his theory of the atom which places the electrons in shells or orbitals. Simulation

Bohr Atom for Hydrogen n = 1 n = 2 n = 3 n = 4 The electron is in the 1 st shell Two Hydrogen atoms collide at high temperature The electron absorbs energy and is moved to a higher energy shell

A photon is generated with the energy difference The electron naturally falls to lower energy shells A blue line is produced n = 1 n = 2 n = 3 n = 4

Bohr Atom for Hydrogen The electron is in the 1 st shell n = 1 n = 2 n = 3 n = 4

Two Hydrogen atoms collide at high temperature The electron absorbs energy and is moved to a higher energy shell n = 1 n = 2 n = 3 n = 4

Two Hydrogen atoms collide at high temperature A photon is generated with the energy difference The electron naturally falls to lower energy shells A green line is produced n = 1 n = 2 n = 3 n = 4

Bohr Atom for Hydrogen The electron is in the 1 st shell n = 1 n = 2 n = 3 n = 4

Two Hydrogen atoms collide at high temperature The electron absorbs energy and is moved to a higher energy shell n = 1 n = 2 n = 3 n = 4

Two Hydrogen atoms collide at high temperature The electron naturally falls to lower energy shells A red line is produced n = 1 n = 2 n = 3 n = 4

Let’s Review n = 1 n = 2 n = 3 n = 4

Bohr Theory The lines can be explained by putting the electrons in fixed shells or orbitals around the nucleus. When electrons absorb energy, through high temperature collisions, they move up to higher energy orbitals. When they fall back down they give off the energy in the form of visible, infrared, and ultraviolet radiation. Light is made when excited atoms lose energy. Bohr Atom 3D

White hot iron emits photons of all colours

The light from space comes from very hot stars

99.99 % of the universe is hydrogen- the 4 lines of hydrogen are most of the photons that come from space

Photons from space allow us to see these images that were generated millions of years ago

Red is hot Sr White is hot Al and Mg Every element has a colour when heated

Green is hot Ba

Blue is hot Cu

Gold is hot Iron

The aurora borealis

Particles from the Sun are caught by the Earth’s magnetic field.

The air emits photons of light as it is energized.

Lightning is electrons heating up the air as they travel from the clouds to the ground.

Electrons from energized air fall to lower orbits.

The hot air gives off light.

Our Sun is very hot and gives off radiation. All light comes from energized electrons And is explained by the Bohr Theory. Dancing Flames Colored Flames