Unit 1: Fundamentals and Quantum numbers

Question 1

What is amplitude (A)?

Answer 1

The height of the wave from midpoint

Question 2

What is wavelength(λ)?

Answer 2

The distance between any two points or between two peaks or troughs (SI units in m, 10^9 nm = m)
Or distance between 1 full cycle

Question 3

What is frequency, ν?

Answer 3

The number of waves per second that pass through a given point (s^-1) or (Hz)

Question 4

What is the relationship between frequency and wavelength?

Answer 4

As frequency increases, wavelength decreases.

lambda.nu = c

where, c is the speed of light = 3.0* 10^8 m/s

Question 5

What can colour be characterized by?

Answer 5

Wavelength and frequency

Question 6

What are the types of wave property?

Answer 6

Constructive and Destructive.

Question 7

How are amplitude and energy related?

Answer 7

light of greater amplitude appears brighter.

Question 8

What dictates the energy of a photon?

Answer 8

The frequency determines the energy of a photon.

Question 9

To eject an electron from the metal what is required?

Answer 9

A minimum frequency of light is required

Question 10

What happens if more than the required frequency of energy was supplied?

Answer 10

The kinetic energy of the ejected electron increases with light frequency.

Question 11

Above the minimum frequency, what happens if you increase the intensity of light?

Answer 11

Increased light intensity increases the number of ejected electrons but not their kinetic energy.

Question 12

When electrons are observed under slit experiment what happens?

Answer 12

They possess wave properties.
Wave diffraction is observed

Question 13

What are the dark and white areas when electron diffraction is observed?

Answer 13

Dark is the waves that are out of phase and cancel out, white are the waves that are in phase and sum to give high intensity light.

Question 14

What happens when electricity is passed through gas?

Answer 14

Atoms cause light to emit, but only the visible part of spectrum is observed. These observed light frequencies are different for each unique atom.

Question 15

What is wave-particle duality?

Answer 15

Light and matter exhibits both wave and particle character.

Question 16

What does squaring the ‘psi’ in the schrodinger model of the atom give?

Answer 16

The probability of finding the electron about the nucleus.

Question 17

What is the principal quantum number?

Answer 17

n - which is the size of the orbital More specifically, it relates to the distance from
the nucleus at which the probability of finding an electron is greatest. This distance is determined by the energy of
the electron.

Question 18

What is the angular quantum number?

Answer 18

l - it is the shape of the orbital,
It is also called the azimuthal quantum number.

Question 19

What is the magnetic quantum number?

Answer 19

ml or m: relates to the orientation of the orbital in space in three-dimensional space.

Question 20

What is the range of angular quantum number?

Answer 20

0…..n-1

Question 21

What is the range of magnetic quantum number?

Answer 21

m = -l……+l

Question 22

How do you find the number of subshells?

Answer 22

First find the l, the if l is 3,

0 – s—1
1—sp—2
2—spd—3
total——5

Question 23

How does probability change with distance from the nucleus?

Answer 23

The closer to the nucleus, the more probability of finding an electron.

Found using the graph, the x-axis has the distance from the radius, the y-axis has the radial probability of distribution

Question 24

How does number of nodes change with increase in orbital size?

Answer 24

The number of nodes also increase.

Question 25

For hydrogen what does energy mainly depend on?

Answer 25

The principal quantum number.

En = -2.18*10^-18 J(1/n^2)

Question 26

Why does energy not depend on l,m in hydrogen atom?

Answer 26

Because they are degenerate.

Question 27

Where is the most stable location of an electron?

Answer 27

Closest to the nucleus, lowest energy and most stable form.

Question 28

What is Pauli’s exclusion principle?

Answer 28

No two electrons in an atom can have the same values for all 4 quantum numbers.

Question 29

What is effective nuclear charge?

Answer 29

The nuclear charge felt by the electron. (if more protons then more attraction on the electron)

If more nuclear charge then energy in the electron decreases

Question 31

What are the electrons that are involved in bonding?

Answer 31

Valence electrons and not core electrons.
Everything from the valence s orbital are involved in bonding.

Question 32

What happens to atomic size top to bottom?

Answer 32

Increases

Question 33

What happens to atomic radius left to right?

Answer 33

Decreases because effective nuclear charge increases

Question 34

What does x indicate in 1s22s22px2?

Answer 34

X indicates 2e- in the same orbital

Question 35

What does sublevel mean?

Answer 35

l = 0 then s is sublevel

l= 1 then p is sublevel

l = 2 then d is sublevel

l = 3 then f is the sunlevel

Question 36

What is ionization energy?

Answer 36

Opposite of Energy, if energy was -2 J then IE is 2J/atom.

Question 37

What will be the shortest wave length possible to excite an electron?

Answer 37

From the given point say 4 to the highest point given in the question. Highest emitted will be given point to the n = 1.

Question 38

What is shielding and effective nuclear charge?

Answer 38

Shielding occurs when inner electrons protect or shield outer electrons from the full nuclear attractive force. The
effective nuclear charge is the nuclear charge an electron actually experiences. As the number of inner electrons
increases, shielding increases, and the effective nuclear charge decreases.

Question 39

What is penetration? How is it related to shielding?

Answer 39

Penetration occurs when the probability distribution of an orbital is large near the nucleus, which results in
an increase of the overall attraction of the nucleus for the electron, lowering its energy. Shielding results in
lessening this effective nuclear charge on outer shell electrons, since they spend most of their time at distances
farther from the nucleus and are shielded from the nuclear charge by the inner electrons. The lower the l quantum
number of an orbital, the more time the electron spends penetrating near the nucleus. This results in a lower energy
for a 3p electron than for a 3d electron in the same atom.