Atomic Theory

Question 1

Electromagnetic radiation

Answer 1

Gamma rays - X-rays - UV - Visible - IR - Microwaves - Radio

Question 2

EMR fundamental characteristics

Answer 2

• move through a vacuum at the speed of light
• wave-like character
• wavelength - h (m) (lambda)
• frequency - v (Hz or s^-1)

Question 3

EMR equation

Answer 3

c = v x h

Question 4

Short wavelength…
Long wavelength…

Answer 4

Short (gamma)…high frequency
Long (radio)…low frequency

Question 5

What 3 phenomena can wave model not explain?

Answer 5

1. Black-body radiation
2. Photoelectric effect
3. Emission spectra

Question 6

Black-body radiation

Answer 6

Wavelength of light (h) depends of T: h(red) > h(blue)
As T increases, peak intensity of radiation will shift to a shorter h (lambda)

Question 7

UV catastrophe

Answer 7

Theory: Intensity = inversely proportional to wavelength
-> longer wavelengths prove, matching experiments
-> shorter wavelengths disprove, predicts infinite intensity
= failure to model

Question 8

Max Planck theory

Answer 8

Energy can only be emitted or absorbed in discrete amounts (quanta)

Question 9

Energy of a photon equation

Answer 9

E = h x v
h = 6.626x10^-34 Js (plancks constant)
v = frequency of radiation (Hz or s^-1)

Question 10

Photoelectric effect (Einstein)

Answer 10

If energy < Threshold, no e- emitted
If energy = threshold, e- emitted (no KE)
If energy > threshold, e- emitted (& excess E = KE)

• light behaves light a wave and a particle

Question 11

Line spectra

Question 12

Emission spectra

Answer 12

• electron drops from higher energy level to lower
• photon of energy is emitted
• detect wavelength of this line

Question 13

Absorption spectra

Answer 13

• photon of energy is absorbed
• electron is excited from lower energy level to higher
• detect wavelength of this line

Question 14

Series formed by transitions starting from (absorption) or ending with (emission)

Answer 14

Emission Spectra:
- Lyman Series: ground state (ni -> nf = 1)
- uv spectrum
- Balmer Series: 1st excited state (ni -> nf = 2)
- visible spectrum

Question 15

De Broglie

Answer 15

If light can behave like both a wave & a particle, then matter should show wave-like properties
-Wave = electron diffraction
-Particle = photoelectric effect

lambda = h/mv

Question 16

Heisenberg

Answer 16

“the more precisely the momentum of a particle is known, the less precisely is its position known”
(delta x)(delta mv) >= h/4pi
(delta mv) = uncertainty of position and uncertainty of momentum