1. Arrangement of electrons in atoms
Chapter 4
Arrangement of electrons in atoms

2. New atomic model section 1
so far, we have three atomic models
Dalton Thomson Rutherford

3. Properties of light
All forms of electromagnetic radiation make up the electromagnetic spectrum.
Electromagnetic radiation is a form of energy that exhibits wavelike behavior as it travels through space.

4. Electromagnetic spectrum

6. Properties of light

8. 𝜆 Properties of light Wavelength
The distance between corresponding points on adjacent waves
Unit of measurement of wavelength is a distance measurement, could be in any meter measurement, meters, centimeters, nanometers

9. Properties of light
Frequency V
Is the number of waves that pass a given point in a specific time, usually one second.

10. Frequency ( v )
Unit of measurement is waves/second
One wave/sec is called a hertz ( Hz)

11. Speed of light (c ) 3.0 x 108 m/s
How fast is light?

12. A jet moving at a ground speed of 500 mph, crosses the U.S. in
4 hours
A jet moving at the speed of light 300,000,000 m/s would travel around the equator of the Earth 7.5 times is a sec.
Light travels at 186,000 mi/sec

13. Frequency and wavelength have a relationship
Speed of light (c) = wavelength (𝜆) x frequency (v)
C = 𝜆v
To solve for 𝜆 : 𝜆 = 𝑐 𝑣 solve for v = 𝑐 𝜆

14. When wavelength decreases then frequency increases
Frequency decreases when wavelength increases
This is called an inverse relationship

15. Photoelectric effect
This effect refers to the emission (release) of electrons from a metal when light shines on the metal.
Packets of light called photons (particles of light) of a certain frequency can knock electrons off of a metal.

16. Go to web, show photoelectric phet

17. Light as a particle
Max Planck was studying the emission of light from hot objects.
He proposed that a hot object does not emit electromagnetic energy continuously, as would be expected if the energy was in the form of a wave.
He suggested that the light was small packets of energy he called quanta.

18. Particles of light
A quantum of energy is the minimum quantity of energy that can be gained or lost by an atom.
Planck stated the following relationship between energy and the frequency of radiation
E = hv

19. Particles of light E = hv
E is energy in joules ( j ) this is a quantum of radiation.
V is frequency in seconds ( s )
h is Planck’s constant. It is always x j/s
v = 𝐸 ℎ

20. A photon is a particle of electromagnetic radiation having zero mass and carrying a quantum of energy.
Einstein explained the photoelectric effect by proposing that electromagnetic radiation is absorbed by matter only in whole numbers of photons. In order for an electron to be ejected from a metal surface the electron must be struck by a single photon with a minimum energy required to knock the electron loose.

22. Line emission spectrum

23. end

24. Ground and excited state
Ground state – is the lowest energy state of an atom
Excited state – a state is which an atom has a higher potential energy than it has in its ground state.

25. Another atomic model Niels Bohr Working with hydrogen gas
Came up with another atomic model
The electrons orbit the nucleus of the atom in energy levels that are specific distances from the nucleus.

26. Bohr atomic model

27. Bohr’s atomic model
Electrons exist in energy levels certain distances from the nucleus.
Bohr’s model explains the behavior of electrons in hydrogen gas and other gases, with the release of energy as light

28. Atom is in ground state – energy, as a photon, is absorbed and the atom moves to excited state, electron moves from lower energy level to a higher energy level atom is in excited state – energy is emited as light and the atom moves back to ground state, electron moves form higher energy level to a lower energy level

29. Now we have four atomic models
Dalton Thomson Rutherford Bohr