Chapter 2-2.5

Question 0

wavelength

Answer 0

the distance between two consecutive peaks or troughs in a wave; lambda, measured in meters

Question 1

electromagnetic radiation

Answer 1

radiant energy that exhibits wavelike behavior and travels through space at the speed of light in a vacuum

Question 2

frequency

Answer 2

cycles per second that pass a given point in space, nu

Question 3

speed of light

Answer 3

c = 3.00 x 10^8 m/s

Question 4

c =

Answer 4

speed of light, 3.00 x 10^8 m/s = lambda nu (wavelength x frequency)

Question 5

what can be viewed as a stream of “particles” called photons

Answer 5

electromagnetic energy

Question 6

what is the energy of a photon?

Answer 6

h x nu where h is Planck’s constant and nu is frequency in cycles per second

Question 7

value of Planck’s constant?

Answer 7

6.626 x 10^-34 J s

Question 8

what was important about Planck’s discovery of Planck’s constant?

Answer 8

it showed that energy was quantized and can occur only in discrete units of size: h nu (where h is Planck’s constant and nu is the frequency of the electromagnetic radiation) – given in Joules since h = 6.626 x 10^-34 J s and nu is given in s^-1 (the s’s cancel out, leaving J)

Question 9

what is emitted when light of a sufficient energy strikes a metal surface and what is it called

Answer 9

e- are emitted in the photoelectric effect

Question 10

how did Einstein come to the conclusion that electromagnetic energies can be viewed as a stream of protons?

Answer 10

by observing and analyzing the KE and qty of emitted electrons in photoelectric experiments

Question 11

hydrogen line spectrum vs continuous spectrum

Answer 11

the continuous spectrum shows all colors of visible light
line spectrum is the emission spectrum of hydrogen that shows only discreet wavelengths of visible light indicating that H has only discreet energy levels

Question 12

quantization

Answer 12

the concept that energy can occur only in discrete units called quanta

Question 13

photons

Answer 13

a quantum of electromagnetic radiation

Question 14

theory of relativity

Answer 14

E = mc^2 where E is energy, m is mass and c is the speed of light
an equation used to show that energy (E) has mass

Question 15

electromagnetic radiation seems to show certain characteristics of waves and of particulate matter this phenomenon is referred to

Answer 15

the dual nature of light

Question 16

diffraction

Answer 16

results when light is scattered from a regular array of points or lines, producing constructive and destructive interference

Question 17

what is created with constructive interference and destructive interference

Answer 17

diffraction pattern

Question 18

describe the quantum model

Answer 18

proposed by Niels Bohr, an e- in a H atom moves around the nucleus only in certain allowable orbits

Question 19

expression for the energy levels available to the electron in the H atom?

Answer 19

E = -2.178 x 10^-18 J (Z^2/n^2) where Z = the number of protons and n = the orbit

Question 20

describe the ground state of an atom

Answer 20

the state in which an atom comes “from the ground” i.e. the lowest possible energy state for an atom

Question 21

what is a standing wave?

Answer 21

a stationary wave on a string; the e- in the H atom is considered a standing wave in the wave mechanical model

Question 22

wave function

Answer 22

a function of the coordinates of an e-‘s position in 3D space that describes the properties of an e-

Question 23

what is the name for a specific wave function for an electron in an atom?

Answer 23

orbital

Question 24

what function, squared gives the probability distribution for the electron

Answer 24

wave function

Question 25

what are the major tenants of the wave (quantum) mechanical model?

Answer 25

e- described as a standing wave the square of the wave function (often called an orbital) gives a probability distribution for the e- position the exact position of the eletron is never known, which is consistent with the Heisenberg uncertainty principle probability maps are used to define orbital shapes

Question 26

Heisenberg uncertainty principle states:

Answer 26

it is impossible to know accurately both the position and the momentum of a particle simultaneously

Question 27

define the probability distribution

Answer 27

the square of the wave function, indicating the probability of finding an e- at a particular point in space

Question 28

radial probability distribution

Answer 28

the total probability of finding the e- in each spherical shell versus the distance from the nucleus

Question 29

What are the boundaries of visible light in meters?

Answer 29

4x10^-7 -- 7x10^-7 m