L5 & 6: The Electronic Configuration of the Atom

Question 1

What is ‘Heisenberg’s uncertainty principle’?

Answer 1

You can never know both the position and the momentum of an electron at the same time

Question 2

What is ‘the Aufbau principle’?

Answer 2

Electrons enter the lowest available energy level first

Question 3

What is ‘Hund’s rule of maximum multiplicity’?

Answer 3

When in orbitals of equal energy, electrons will try to remain unpaired.

Bus rule: When you get on a bus, you go for the vacant row before sitting next to another person

Question 4

What is the ‘Pauli exclusion principle’?

Answer 4

No two electrons can have the same four quantum numbers. Only 2 electrons can go in each orbital, providing they are of opposite spin.

Question 5

How can an electron jump up to a higher energy level?

Answer 5

Absorbing a photon of light

Question 6

How can an electron descend an energy level?

Answer 6

Emitting a photon of light

Question 7

How can you determine the amount of energy between energy levels?

Answer 7

Measure the energy of the photon emitted by a descending electron

Question 8

What is ‘a measure of the amount of energy needed to remove electrons from atoms or ions’?

Answer 8

Ionisation energy

Question 9

Define ‘first ionisation energy’

Answer 9

The energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous positive ions

Question 10

Are ionisation energies positive or negative? Why?

Answer 10

Positive - to overcome the attraction between an electron and the protons in the nucleus, energy must be added to the system.

Question 11

True or false: lower nuclear charges result in higher ionisation energies

Answer 11

False. Higher nuclear charges result in higher ionisation energies.

The greater the pull of the nucleus, the harder it is to pull an electron away. Therefore, more energy is required.

Question 12

Define ‘electron affinity’

Answer 12

The amount of energy needed to add electrons to atoms or ions

Question 13

What is ‘the energy needed to add one mole of electrons to one mole of gaseous atoms to form one mole of gaseous negative ions’?

Answer 13

First electron affinity

Question 14

Are electron affinities positive or negative?

Answer 14

Negative. Energy is released when electrons are added to an atom

Question 15

True or false: The more negative the electron affinity, the more stable the negative ion that is formed

Answer 15

True

Question 16

True or false: Atomic size increases along a period and down a group

Answer 16

False. Atomic size decreases along a period; increases down a group

Question 17

True or false: First ionisation energy increases across a period

Answer 17

True

Question 18

True or false: First ionisation energy increases down a group

Answer 18

False. First ionisation energy decreases down a group

Question 19

True or false: Patterns of first ionisation energy are opposite to the patterns of atomic size (i.e. as atomic size increases, 1st I.E. decreases, and vice versa)

Answer 19

True

Question 20

Fill in the gaps:

First electron affinity becomes _____(1)______ negative across a period, and _____(2)_____ negative down a group.

Answer 20

(1) more

(2) less

Question 21

What are the three most important factors to take into account when explaining trends in the periodic table?

Answer 21

1) Charge
2) Shielding
3) Atomic size

Question 22

What are the four quantum numbers required to specify the character of an electron?

Answer 22

1) Principal (n)
2) Azimuthal or subsidiary (l)
3) Magnetic (m)
4) Spin (s)

Question 23

What three things can be determined by the principal quantum number (n)?

Answer 23

1) Distance of electron from the nucleus - higher n = further from nucleus
2) Energy of electron - higher n = higher energy e-
3) Number of electrons a shell can hold - 2n^2

Question 24

How many electrons can L-shell hold?

Answer 24

8

L-shell n = 2

2n^2 = 2 x (2^2) = 2 x 4 = 8

Question 25

How many electrons can N-shell hold?

Answer 25

32

N-shell n = 4

2n^2 = 2 x (4^2) = 2 x 16 = 32

Question 26

What is the rule for allowed values of n?

Answer 26

n = value greater than 0

Question 27

What do the azimuthal or subsidiary values correlate with?

Answer 27

The subshells.

l = 0 = s-subshell
l = 1 = p-subshell
l = 2 = d-subshell
l = 3 = f-subshell

Question 28

What is the rule for allowed values of l?

Answer 28

l = 0 to (n-1)

Question 29

If n = 3, what are the allowed values of l?

Answer 29

l = 0, 1, 2

Question 30

If n = 1, what are the allowed values of l?

Answer 30

l = 0

Question 31

How many electrons can a given subshell hold?

Answer 31

Calculate using formula 2(2l+1)

Question 32

What is the maximum number of electrons that can be held in the d subshell?

Answer 32

10

d-subshell l=2

2(2x2+1) = 4+1 = 5

5 x 2 = 10

Question 33

Which subshell is spherical?

Answer 33

S-subshell (l=0)

Question 34

What shape is the orbital represented by l=2?

A) Spherical
B) Dumbbell
C) Complex
D) Most complex

Answer 34

C) Complex

l=2 is the d-subshell, which is a complex shape.

Question 35

True or false: Putting the n value and the l value together (nl) gives you the specific subshell number

Answer 35

True.

E.g. Shell M, n=3, l=0 is the 3s subshell; l=1 is the 3p subshell….etc

Question 36

What is the rule for allowed values of m?

Answer 36

m = value ranging from -l to +l, including 0

Question 37

If l=0, what are the allowed values of m?

Answer 37

m = 0

Question 38

If l=2, what are the allowed values of m?

Answer 38

m = -2, -1, 0, +1, +2

Question 39

If n = 3, what is the maximum allowed value of m?

Answer 39

+2

Max value of l=2, therefore the max value of m = +2

Question 40

What does the spin quantum number show?

Answer 40

Whether the electron is spinning clockwise (+1/2) or anticlockwise (-1/2)

Question 41

If there are two electrons in the same orbital, what will their s values be?

Answer 41

One will be +1/2 and the other will be -1/2

Question 42

What is the rule for allowed values of s?

Answer 42

s = -1/2 or +1/2

Question 43

Which principle states ‘you cannot determine the position and momentum of an electron at the same time’?

Answer 43

Heisenberg’s Uncertainty Principle

Question 44

Which principle states ‘electrons enter the lowest available energy level first’?

Answer 44

The Aufbau Principle

Question 45

Which principle states ‘when in orbitals of equal energy, electrons will try to remain unpaired’?

Answer 45

Hund’s Rule of Maximum Multiplicity

Question 46

Which principle states ‘No two electrons can have the same four quantum numbers’?

Answer 46

Pauli Exclusion Principle

Question 47

True or false: In transition metals, electrons in the 4s orbital are removed before any electrons in the 3d orbitals

Answer 47

True

Question 48

While analysing an element’s successive ionisation energies you notice that there are some large jumps that are significantly larger the others. What does this tell you?

Answer 48

A large jump in ionisation energy indicates a change in energy level

Question 49

What is different about the orbital filling of chromium and copper?

Answer 49

When the d-orbital is almost full, or almost half full, it can steal an electron from the preceding s-orbital

Question 50

What is Gd3+ commonly used for in medicine?

Answer 50

As a contrast agent in MRI scanning. Its 7 unpaired electrons make it ideal