Lecture 2- Atomic theory 2

Question 1

frequency

Answer 1

the number of times a wave repeats itself per second

Question 2

color with shortest and longest wavelength

Answer 2

shortest=violet 
longest=red

Question 3

color with highest and lowest frequency

Answer 3

highest=violet
lowest=red

Question 4

Max Planck

Answer 4

• Quantum theory
• Hypothesized that the energy radiated from a heated object, such as stove element or a lightbulb filament, is emitted in discrete units, or quanta

Question 5

Quantum theory

Answer 5

• Energy increases in discrete units and is increased by a full quantum, or not at all

Question 6

The photoelectric effect origins

Answer 6

scientists knew that certain clean metal surfaces would shed electrons when certain frequencies of light were shined on them

Question 7

The photoelectric effect

Answer 7

1. Highly intense low frequency light does not eject any electrons, even if it shines on the surface for several days
2. When the threshold frequency is reached, electrons are ejected immediately
3. Increasing the intensity of the light as a frequency that will cause electrons to eject results in a higher ejection rate. However, all ejected electrons share the sam velocity.
4. Increasing the frequency of the light increases the velocity of the ejected electrons. However, all ejected electrons share the same velocity

Question 8

Einstiens theory

Answer 8

• A beam of light is a stream of particles called photons
• every of a photon is related to its frequency according to planks law (E=hv)
• The quantum of Planck is a particle- a photon
• If the frequency of a photon is below a certain threshold, no electrons are ejected
• If the frequency of a photon is below a certain threshold, no electrons are ejected
• If the frequency is at or above a certain threshold, its energy is transferred to the electron
• This causes the electron to overcome the forces of attraction holding it to the metal
• The electron absorbs the photon

Question 9

Bohr model of the atom

Answer 9

• forces of attraction between the electrons and nucleus result from opposite charges.
• regular circle model

Question 10

Shielding effect

Answer 10

• electrons furthest from the nucleus are partly shielded by the inner core electrons
• reduces electrostatic attraction between outer electrons and nucleus

Question 11

First ionization energy

Answer 11

• minimum amount of energy required to remove the outermost, least tightly held electron from an atom in the gas phase

A(g) yields A^+(g)+e-

Question 12

shell model first three rows

Answer 12

2, 8, 8

Question 13

subshells n=

Answer 13

n=1 hold 1s
n=2 holds 2s and 2p
n=3 holds 3s, 3p, 3d

Question 14

shielding effect within a shell

Answer 14

although the average distance between the nucleus and electors decreases as subsequent sub shells are added within a shell, the ionization energy decreases due to an increase in the shielding effect.

Question 15

how PES works

Answer 15

• works by photoelectron effect
• only shows EL and sub levels
• Bohr and shell to correct because no distinction between sub levels
• IE- energy to remove the highest energy in a gaseous state
• spiky graph

Question 16

How did Einstien use experimental evidence related to the photoelectric effect to conclude that quantized energy must be contained by individual particles

Answer 16

by individual particles. He emitted a stream of particles and noticed that there were photons that hit the collector plate individually and once emitted, they were able to transfer energy to turn on and power a lightbulb, proving that quantized every is concentrated in particles