Chapter 38

The Atom and the Quantum

Quantum Physics

• The branch of physics that is the general study of quanta (singular-quantum) in the microworld of the atom.

Models

used to study the atom because there is no direct view of an atom’s internal structure

Bohr Model

developed by Neils

Bohr in 1913;

planetary model

Light used to explain atoms

Does light move as particles or as waves?

Answer: Light moves in particles

that act as waves

Max Planck and Albert Einstein

Light is in packets of energy called quanta.

We now call quanta “photons”

This idea gives use to quantum theory and quantum mechanics.

Quantum Mechanics

the branch of physics that is the general study of the motion of quanta in the microworld of the atom.

Light from Electrons

Electrons are in electron levels around the nucleus.

When energy is applied to the atom, electrons enter an excited state and jump to the next higher level.

Light from Electrons

When returning to regular level, energy is released in

the form of light (emission).

Each atom has a unique light emission.

Light from Electrons

Tungsten (W)

Filament in regular light

bulb emits “white or normal light”