Intro to Atoms and Energy

1
Intro to Atoms and Energy

• Chapter 11. Sections 11.1-11.3

2
Rutherfords Atom

• Remember back, way back to models of the atom
• Rutherfords model was that the nucleus of the
  atom has a positive charge and the outer part is
  negatively charged.

3
Rutherfords Atom Cont

• Now of course we now know that isnt exactly
  correct
• But we have to look at some properties of energy
  and light to understand how the atom looks

4
Energy and Light

• Energy can be transmitted by electromagnetic
  radiation.
• There are many types
• X-rays
• Visable light
• Microwaves
• Radio waves
• But they all are all still waves

5
A seagull floating on the ocean moves up and down
as waves pass.
6
Energy and Light cont

• So in order to understand electromagnetic
  radiation, we have to remember stuff about waves.
• All waves have three properties wavelength,
  frequency, and speed
• Wavelength is the distance between two
  consecutive waves
• Frequency is how many waves pass a certain point
• Speed is how fast the wave travels

7
Energy and Light cont

• Although electromagnetic radiation does not move
  matter (or a medium) like sound waves or water
  waves it still works in similar ways
• All electromagnetic radiation has the same speed
  (the speed of light) however the wavelength
  changes by the type of wave.

8
Energy and Light cont

• Electromagnetic waves also do not require a
  medium.
• An EM wave carries energy
• Sometimes EM radiation behaves more as a particle
  than as a wave.
• Rather than being a wave of energy it can be
  thought of a stream of particles of energy called
  Photons

9
Energy and Light cont

• So we say that light (even light we cannot see)
  has characteristics of both a wave and a
  particle, this is called the wave-particle nature
  of light
• Different wavelengths carry different amounts of
  energy
• Example red light (lower frequency) carries less
  energy than blue light (higher frequency)

10
Emission of Energy by Atoms

• When atoms get excited they absorb energy
• They can release this energy in the form of a
  photon.
• The energy of the photon is what determines the
  type of radiation released.

11
An excited lithium atom emitting a photon of red
light to drop to a lower energy state.
12
Homework

• Read pages 322-327. Problems 1-4 on page 327.
  Problems 5 and 7 on page 354