Chapter 2 - The Quantum Mechanical Model of the Atom

Question 1

How do electrons behave?

Answer 1

much differently than large objects (classical physics does not describe electrons)

Question 2

What is Quantum Mechanics?

Answer 2

physics of the really small, forms the basis of our understanding of mater and its behaviour at the subatomic level

Question 3

What is light?

Answer 3

A form of electromagnetic radiation
Composed of perpendicular oscillating waves, one for the electric field and one for the magnetic field

Question 4

In what way does light move?

Answer 4

At a constant speed. notified by ‘c’ (speed of light) = 3.00x10^8 m/s

Question 5

What is Amplitude?

Answer 5

vertical height of a crest or depth of a trough
determines the lights intensity/ brightness
greater amplitude = greater intensity

Question 6

What is Wavelength?

Answer 6

distance between 2 adjacent crests or troughs etc. is measured in units like metres, micrometres and nanometres

Question 7

What is frequency?

Answer 7

the number of waves that pass a point in a given period of time
units are cycles per second (s^-1) or hertz (Hz)
1s^-1 = 1Hz

Question 8

What is the relationship between wavelength and frequency?

Answer 8

they are inversely proportional

Question 9

What is the equation for Frequency?

Answer 9

Frequency (s^-1) = Speed of light (3.00x10^8) / wavelength (m)

Question 10

What is total energy (light as a wave)?

Answer 10

proportional to the amplitude of the waves and their frequency
The larger the amplitude, the more force it has
The more frequently the waves strike, the more total force there is.

Question 11

On the electromagnetic spectrum what does a shorter wavelength mean?

Answer 11

(high frequency) light has higher energy

Question 12

Which wave of light has the lowest energy?

Answer 12

Radio-wave light

Question 13

Which wave of light has the highest energy?

Answer 13

Gamma-ray light

Question 14

What are some examples if high-energy electromagnetic radiation and what could they do to molecules?

Answer 14

UV, X-ray, Gamma can potentially damage biological molecules

Question 15

What is the wavelength of Gamma rays?

Answer 15

10^-15 m

Question 16

What is the wavelength of radio waves?

Answer 16

10^5 m

Question 17

list the different types of wavelength from low to high energy

Answer 17

Radio, Microwave, Infrared, Visible , Ultraviolet, X-Ray, Gamma Ray

Question 18

What is the region for visible light?

Answer 18

between 400nm - 750nm (small)

Question 19

What is Interference (waves)?

Answer 19

the interaction between multiple waves

Question 20

What is constructive interference?

Answer 20

waves that are in phase and add to make a larger wave

Question 21

What is destructive interference?

Answer 21

waves that are out of phase and cancel each other out

Question 22

What is diffraction?

Answer 22

When propagating waves encounter an opening in a barrier and bend around it. (travelling particles do not diffract)

Question 23

What does the diffraction of waves through 2 slits result in?

Answer 23

an interference pattern (alternating regions of constructive and destructive interference) (waves out of phase = dark spot & vice versa)

Question 24

What is the photoelectric effect?

Answer 24

that when light hits a metal surface, electrons can be ejected

Question 25

What is the driving force in the photoelectric effect?

Answer 25

the frequency of the light. There is a threshold frequency needed to be met before electrons are emitted. High frequency light from a dim source causes electron emission without any lag time.

Question 26

What is the equation for Photon Energy?

Answer 26

E = hv (h=Planck's Constant) (v=frequency)

Question 27

What is Planck's Constant?

Answer 27

6.626 x 10^-34 (J/s)

Question 28

What is the equation for Frequency?

Answer 28

v=c/λ(c=speed of light) (λ=wavelength)

Question 29

What is the atomic spectra?

Answer 29

when atoms absorb energy, extra energy in atoms or molecules can be released as light (used in fireworks)

Question 30

How do we see different colours?

Answer 30

different atoms (elements) have distinct wavelengths that they emit

Question 31

What does a line spectra show?

Answer 31

the different wavelengths of light emitted. Easy comparison between elements

Question 32

Why was the Bohr model of the atom needed?

Answer 32

the nuclear model of the atom does not explain what structural changes occur when the atom gains or loses energy

Question 33

What was Bohr's major idea about electrons in relation to the atom?

Answer 33

the energy of the atom was quantised, and that the amount of energy in the atom was related to the electron's position in the atom.

Question 34

What did De Broglie propose?

Answer 34

particles could have wave-like character

Question 35

What is De Broglie's relation?

Answer 35

wavelength = Planck's constant / (mass x velocity) λ = h/mv

Question 36

What is Heisenberg's uncertainty principal?

Answer 36

Impossible to know precisely where an electron is and what path it follows

Question 37

What is the wave/particle description of light?

Answer 37

by mathematical mode (can't see atoms and observe behaviour directly)

Question 38

What does Schrodinger's equation calculate?

Answer 38

the probability of finding an electron with a particular amount of energy at a particular location in the atom

Question 39

What do the solution of Schrodinger's equation calculate?

Answer 39

a probability distribution map of a region where the electron is likely to be found called an orbital

Question 40

What are the 4 Quantum numbers?

Answer 40

Principal quantum number Angular momentum quantum number Magnetic quantum number Spin quantum number

Question 41

What is the principal quantum number represent and what is it's symbol?

Answer 41

Energy level, denoted by 'n'

Question 42

What does the angular momentum number represent and what is it's symbol?

Answer 42

Orbital type, denoted by 'l'

Question 43

what does magnetic quantum number represent and what is it's symbol?

Answer 43

position of an orbital in X-Y-Z plot. denoted by 'm sub l' (m with l as like a small lower letter)

Question 44

What does spin quantum number represent and what is it's symbol?

Answer 44

orientation of the spin of the electron, denoted by 'm sub s' (m with s as like a small lower letter)

Question 45

What is the number range for Principal Quantum number?

Answer 45

whole number integer ≥ 1

Question 46

In principal quantum number as n increases what happens to the energy of electron and the distance from nucleus?

Answer 46

they both increase

Question 47

In the angular momentum quantum number what values can l have?

Answer 47

integer values from 0 to (n-1)

Question 48

If the l value is 0 what is the letter designation?

Answer 48

s

Question 49

If the l value is 1 what is the letter designation?

Answer 49

p

Question 50

If the l value is 2 what is the letter designation?

Answer 50

d

Question 51

If the l value is 3 what is the letter designation?

Answer 51

f

Question 52

What can the values of Magnetic Quantum number be?

Answer 52

integers from -l to +l

Question 53

when l = 0 what are the possible 'm sub l' values?

Answer 53

0

Question 54

when l = 1 what are the possible 'm sub l' values?

Answer 54

-1,0,1

Question 55

when l = 2 what are the possible 'm sub l' values?

Answer 55

-2,-1,0,1,2

Question 56

when l = 3 what are the possible 'm sub l' values?

Answer 56

-3,-2,-1,0,1,2,3

Question 57

What is the spin behaviour of an electron?

Answer 57

+1/2 or -1/2

Question 58

How do you indicate the electron spin movement?

Answer 58

by a half arrow (⇀ )

Question 59

In the atomic spectra when an electron is excited what does it do?

Answer 59

transitions from an orbital in a lower energy level to an orbital in a higher energy level

Question 60

In the atomic spectra when an electron is relaxed what does it do?

Answer 60

transitions from an orbital in a higher energy level to an orbital in a lower energy level

Question 61

What is the equation for total electron energy?

Answer 61

= -2.18 x 10^-18 J ((1/N^2f) - (1/n^2i)) f=final state i=initial state

Question 62

What is a node? (atomic spectra)

Answer 62

areas of no probability of electron occurring