Chemistry Final Exam

Question 1

What are examples of electromagnetic radiation

Answer 1

Visible light, x- rays, radio waves, & microwaves

Question 2

What are the properties of the wave nature of light?

Answer 2

1. Frequency (v)
2. Wavelength (lambda)
3. Speed ( meters)
4. Amplitude ( height of the crest of a wave)

Question 3

electromagnetic spectrum:

Answer 3

a continuum of wavelengths of radiant energy

Question 4

From lowest to highest frequency, what order are the different areas of the electromagnetic spectrum

Answer 4

Gamma ray, X-ray, Ultraviolet, Visible light, infrared, Microwave, Radio waves

Question 5

Refraction definition

Answer 5

The phenomenon in which a wave changes its speed and therefore its direction as it passes through a phase boundary to a different medium

Question 6

`Dispersion definition

Answer 6

the phenomenon in which a wave striking the edge of an object bends around it. A wave passing through a slit as wide as its wavelength forms a circular wave

Question 7

Interference definition:

Answer 7

Constructive and destructive; constructive: amplitudes add together to form a brighter region, destructive: amplitudes cancel to form a darker region`

Question 8

Blackbody radiation

Answer 8

When a solid is heated to about 1000K, it begins to emit visible light

Question 9

Particle nature of light

Answer 9

1. Blackbody radiation

2. quantum theory E= nhv

Question 10

Planck’s constant:

Answer 10

6.626 x 10^-34 (J)(s)

Question 11

Quantum

Answer 11

A packet of energy equal to hv. The smallest quantity of energy that can be emitted or absorbed

Question 12

Photoelectric effect and the Photon theory of light

Answer 12

When monochromatic light of sufficient frequency shines on a metal plate, a current is produced

Question 13

Threshold frequency

Answer 13

For current to flow, the light shining on the metal must have a minimum or threshold frequency

Question 14

Absence of time lag:

Answer 14

Current flows the moment light of the minimum frequency shines on the metal regardless of the light’s intensity

Question 15

Photon theory

Answer 15

Ephoton = hv = deltaEatom

Question 16

Line spectrum definition

Answer 16

a series of fine lines at specific frequencies separated by black spaces

Question 17

Rydberg equation

Answer 17

1/lambda = R((1/n1^2)-(1/n2^2)

Question 18

Postulates of the Bohr model

Answer 18

1. The H atom has only certain energy levels which Bohr called stationary states. Each state is associated with a fixed circular orbit around the nucleus. The higher the energy level, the farther it is from the nucleus
2. The atom does NOT radiate energy while in one of its stationary states
3. The atom changes to another stationary state (the electron moves to another orbit) only by emitting or absorbing a photon. The energy of the photon equals the energy of the two states

Question 19

Features of the Bohr’s model

Answer 19

1. Quantum numbers and electron orbit (n is a positive integer)
2. Ground state
3. Excited States
4. Absorption
5. Emission

Question 20

Ground State definition

Answer 20

When the electron is in the 1st orbit (n=1), it is closest to the nucleus and the H atom is in its lowest energy level

Question 21

Excited states definition

Answer 21

Any other orbit than the ground state

Question 22

Absorption

Answer 22

If an atom absorbs a photon whose energy equals the difference between lower and higher energy levels, the electron moves to a higher energy orbit

Question 23

Emission definition

Answer 23

If an H atom in a higher energy level (electron in a farther orbit) returns to a lower energy level (electron in a closer orbit), the atom emits a photon whose energy equals the difference between the two levels

Question 24

How the model explains line spectra

Answer 24

Since an atom’s energy is not continuous, but rather has only certain states, an atomic spectrum is not continuous

Question 25

Limitations of Bohr’s model

Answer 25

failed to predict the spectra of any other atom; repulsion and additional electron reactions make the actions too complex for Bohr’s model

Question 26

λ=h/mu

Answer 26

De broglies equation

Question 27

Electron Affinity

Answer 27

the energy change when one mole of an electron is added to one mole of the gaseous atom or ion