Topic 4 The Quantum Realm

Question 1

What is wave-particle duality?

Answer 1

This is the phenomenon where electromagnetic radiation and other sub atomic particles appear to travel as waves, but interact with matter as if they were a stream of particles such as photons.

Question 2

What are the components of a wave?

Answer 2

• Peak, highest point in the wave
• trough, lowest point in the wave
  -wavelength, the distance between two peaks.
• amplitude, the distance between the x axis and a peak or trough

Question 3

What is interference?

Answer 3

The phenomenon in which two or more waves interact to create distinct regions in which the wave amplitude is enhanced or reduced. This is known as constructive and destructive interference, respectively.

Question 4

De broglie wavelength formula (equation)

Answer 4

λ = h / (mv)

Where λ is wavelength, m is mass of the object, v is speed and h is planck’s constant (6.626x10^(-34) kg m^2 s^-1).

Question 5

Frequency period (equation)

Answer 5

f = 1 / T

Where T is the period of the wave.

The period of a wave (T) is the amount of time it takes two consecutive peaks to pass a set point.

Question 6

Frequency wavelength equation

Answer 6

f = c / λ

Where c is the speed of light in a vacuum (3x10^8 m/s), and λ is the wavelength

Frequency is measured in Hertz, Hz, which is equal to s^-1

Question 7

Calculate the energy of photons

Answer 7

E = hf

Energy = plancks constant (6.626x10^-34) x frequency

Question 8

What is the Heisenberg uncertainty principle?

Answer 8

This tells you that the you cannot know the precise location and velocity of a particle. If you knew the exact position of a particle, you can know nothing about its velocity and vice verse.

Question 9

What is quanta?

Answer 9

This can be thought of as a packet of energy with an exact value that is absorbed by a particle to go from one energy level to another, or emitted to go down an energy level.

Question 10

What are indeterminacies?

Answer 10

These are things that cannot be known or determined no matter how good of an experiment is produced.

Question 11

What is a standing wave?

Answer 11

A wave whose profile oscillates in time but is fixed in space. It has a series of nodes (stationary points) and antinodes (moving points).

Question 12

What is an orbital?

Answer 12

This refers to the shape of on electrons waveform. S orbitals are round, p orbitals are dumbbell shaped and d orbitals are clover shaped.

Question 13

What is the principle quantum number?

Answer 13

This is the first quantum number and is denoted ‘n’. It can only have values of integers greater than or equal to one.

Question 14

What is the orbital quantum number?

Answer 14

This is the second orbital member, given the symbol ‘l’. When used to distinguish quantum states that share a common value of ‘n’, it can only take the whole number values from l=0 to l=n-1.

Question 15

What is the magnetic quantum number?

Answer 15

The third quantum number is represented by the symbol ‘ml’ and it can have any whole value between -l and +l.

Where there are a total of 2l+1 different values of ml for any different value of l.

Question 16

What is the spin quantum number?

Answer 16

This is the fourth quantum number, ‘ms’. It has 2 valueswhich are +1/2 or -1/2.

Question 17

What is quantum state?

Answer 17

This is the combination of the shape of the orbital and the direction of spin defined by the four quantum numbers n, l, ml and ms.

To calculate the total quantum states for each value of I the formula 4l+2 can be used.

Question 18

What is the ground state?

Answer 18

This is the lowest possible energy level an electron can be in.

Question 19

What is an excited state?

Answer 19

This is when on electron is in a higher energy level than its ground state.

Question 20

Calculate the energy level (En) of hydrogen (equation)

Answer 20

En = (-13.6 eV) / n^2

Question 21

What is a hydrogen like ion?

Answer 21

This refers to any ion that has a single electron such as He+ and Li2+

The orbitals of these hydrogen like ions are scaled down by a factor of Z^2 ( where Z is the atomic number of the ion) but otherwise have the ecad same shape and quantum numbers as hydrogen orbitals.

Question 22

Calculate the energy levels of hydrogen like ions (equation)

Answer 22

En = (Z^2 x -13.6 eV) / n^2

Where Z is the atomic number.

Question 23

What letters are used to represent the number value for The quantum number l?

Answer 23

s, p, d, f are used to represent values of l

Where

S equals l=0
P equals l=1
D equals l=2
F equals l=3

So n=1 l=0 is 1s and n=3 l=2 is 3d

Question 24

What is the Pauli exclusion principle?

Answer 24

This principle bans any a elections from having the some quantum state.

Question 25

What is the madalung rule?

Answer 25

This predicts that the ground state of an atom is formed by completely filling orbitals in the order of the sum of the principle and orbital quantum numbers, n + l. For all orbitals where n + l are the same, then the orbitals fill in order of increasing n.

Question 26

What is screening?

Answer 26

This is the process where electrons closer to the nucleus cancel out some of the positive charge from the nucleus.