3.1.1 - Atomic Structure (not finished)

Question 1

What did John Dalton discover in 1803?

Answer 1

He theorised that there must be a smallest bit of an element

Question 2

What did J.J. Thompson discover in 1904?

Answer 2

Electrons - randomly placed (Plum Pudding Model)

Question 3

What did Ernest Rutherford discover in 1911?

Answer 3

The nucleus - gold leaf experiment - electrons orbit

Question 4

What did Niels Bohr discover in 1913?

Answer 4

Electrons are arranged in shells

Question 5

What did Erwin Schrodinger discover in 1926?

Answer 5

Quantum mechanics - orbitals

Question 6

Define atomic number

Answer 6

The atomic number is equal to the amount of protons in the nucleus

Question 7

Define mass number

Answer 7

The mass number is equal to the number of protons and neutrons combined

Question 8

Define isotopes

Answer 8

Isotopes are atoms with the same number of protons but different number of neutrons

Question 9

What is a Cation?

Answer 9

A positive ion (lost electrons)

Question 10

What is an Anion?

Answer 10

A negative ion (gained electrons)

Question 11

Define First ionisation energy

Answer 11

The amount of energy needed to remove one mole of electrons from a mole of atoms, in the gaseous state

Question 12

What is the trend in first ionisation energies down a group?

Answer 12

Decreases

Question 13

What is the trend in first ionisation energies across a period?

Answer 13

Increases

Question 14

What does a mass spectrometer measure?

Answer 14

1. Relative abundance
2. Mass/charge ratio

Question 15

What are the 4 steps in time-of-flight mass spectrometry?

Answer 15

1. Ionisation
2. Acceleration
3. Ion drift
4. Detection

Question 16

What happens in electrospray ionisation?

Answer 16

• Sample is dissolved in a volatile solvent
• Sample is injected through a needle at a high voltage
• Sample is ionised by gaining a proton

Question 17

What happens in electron-impact ionisation?

Answer 17

• Sample is vaporised
• High-energy electrons are fired at sample
• From an electron gun
• One electron is knocked off each particle (forming a positive ion)

Question 18

What is the relative mass of an electron?

Answer 18

1/1840

Question 19

Why do isotopes of the same element have the same chemical properties?

Answer 19

They have the same electron configuration

Question 20

Explain the gold leaf experiment in terms of point P and point Q

Answer 20

• Rutherford fired He2+ ions at a sheet of gold foil/leaf
• When the He2+ ions arrived at point P, he concluded that most of the atom is empty space
• A very small number of He2+ ions were detected at point Q. He concluded that the atom must have a small, positive nucleus

Question 21

Write the first ionisation energy of potassium (K)

Answer 21

K(g) -> K+(g) + e-

Question 22

Write the second ionisation energy of silver (Ag)

Answer 22

Ag+ (g) -> Ag2+ (g) + e-

Question 23

How does nuclear charge influence ionisation energy?

Answer 23

The more protons, the stronger the forces of attraction between the nucleus and the outer electron. Therefore, the amount of energy required to remove the electron is higher

Question 24

How does distance from the nucleus influence ionisation energy?

Answer 24

The closer the electrons are to the nucleus, the stronger the forces of attraction between the nucleus and the outer electron. Therefore, the amount of energy needed to remove the electron is higher

Question 25

How does shielding influence ionisation energy?

Answer 25

Shells with more shielding have their outer electrons blocked and repelled. This means there is a weaker force of attraction between the outer electron and nucleus so the amount of energy required to remove the electron is lower

Question 26

Explain a graph showing the Ionisation Energy (IE) for Boron

Answer 26

- The IE increases (1-3) as each electron is being removed from a more positive ion each time - The attraction becomes stronger as there are less electrons being attracted by the same number of protons - The 4th electron is moved from a shell closer to the nucleus so is more strongly attracted to the nucleus and therefore requires more energy to remove

Question 27

Why is the second ionisation energy of Be higher than the first?

Answer 27

The electron is removed from an ion that already has a positive charge

Question 28

Why is Li a bigger atom than Be?

Answer 28

- Both atoms have the same number of shells - They both have that same amount of shielding - But Be has more protons - So it attracts the outer most electron more strongly, making it smaller

Question 29

Why is Li a bigger atom than He?

Answer 29

- More shells so more shielding - Li has more electron shells which are further away from the nucleus - The outer electrons are more shielded - The outer electron is less strongly attracted to the nucleus

Question 30

Why does He have the highest Ionisation Energy of all elements?

Answer 30

- Same shielding as H (none) - More protons

Question 31

Explain the GENERAL trend in first Ionisation Energies across a period

Answer 31

- The first IE will increase - There are more protons in the nucleus - The shielding remains the same - So the attraction increases between the nucleus and outer electron

Question 32

What is the maximum number of electrons in shell 1?

Answer 32

2

Question 33

What is the maximum number of electrons in shell 2?

Answer 33

8

Question 34

What is the maximum number of electrons in shell 3?

Answer 34

18

Question 35

What is the maximum number of electrons in shell 4?

Answer 35

32

Question 36

What shape is an s orbital?

Answer 36

Spherical

Question 37

What shape is a p orbital?

Answer 37

Egg timer shaped

Question 38

How many orbitals are there in: s sub-shell? p sub-shell? d sub-shell?

Answer 38

s sub-shell = 1 p sub-shell = 3 d sub-shell = 5

Question 39

What is the highest energy electron?

Answer 39

The outer most electron on an atom or ion - the furthest from the nucleus

Question 40

What is the electron configuration for chromium?

Answer 40

1s2 2s2 2p6 3s2 3p6 4s1 3d5