Atomic Structure

Question 1

What was Dalton’s model of the atom?

Answer 1

Billiard Ball
- all atoms of the same element have the same mass and are the same
- tiny
- indivisible

Question 2

What was JJ Thompson’s model of the atom?

Answer 2

Plum Pudding
- discovered the electron
- negatively charged electrons floating in a ‘sea’ of positive charge

Question 3

What was Rutherford’s model of the atom?

Answer 3

• discovered the nucleus
• holds most of the mass in a tiny centre with positive charge
• lots of empty space

Question 4

How did Rutherford prove his model?

Answer 4

Gold foil experiment
- shooting alpha particles at some gold foil and seeing how many particles deflect and where they go

Question 5

What was Bohr’s model of the atom?

Answer 5

• discovered energy shells
• each shell is fixed and has a fixed energy level
• electromagnetic radiation is either absorbed or emitted when an electron moves shell

Question 6

What was Chadwick’s model of the atom?

Answer 6

• discovered the neutron
• a sub-atomic particle with neutral charge that is in the nucleus

Question 7

what is the charge on a proton?

Answer 7

+ 1.6 x 10⁻¹⁹

Question 8

what is the charge on neutron?

Answer 8

0

Question 9

what is the charge on an electron?

Answer 9

• 1.6 x 10⁻¹⁹

Question 10

what is the mass (kg) of a proton?

Answer 10

1.67 x 10⁻²⁷

Question 11

what is the mass (kg) of a neutron?

Answer 11

1.67 x 10⁻²⁷

Question 12

what is the mass (kg) of an electron?

Answer 12

9.11 x 10⁻³¹

Question 13

what is the relative masses of p, n and e?

Answer 13

p = +1
n = +1
e = 1/1836

Question 14

what is the relative charges of p, n and e?

Answer 14

p = +1
n = 0
e = -1

Question 15

what is an isotope?

Answer 15

atoms of the same element, which therefore have the same number of protons and electrons, but have a different number of neutrons

Question 16

what is relative atomic mass (Ar)?

Answer 16

the average mass of an atom of an element compared to the 1/12 the mass of a carbon-12 isotope

Question 17

how to calculate Ar?

Answer 17

(isotope mass x %abundance) / 100

Question 18

how to calculate Mr?

Answer 18

(mass1 x y) + (mass2 x (100 - y)) / 100

e.g. (203 x y) + (205 x (100 - y)) / 100
y = 30

Question 19

what is relative molecular mass (Mr)?

Answer 19

the average mass of a molecule relative to one twelfth of the mass of an atom of carbon-12.

Question 20

how can you measure the mass and abundance of each isotope in an element (Ar) or to find the relative molecular mass of a substance?

Answer 20

Time of Flight (TOF) Mass Spectrometer

Question 21

what are the 5 phases of mass spectrometry?

Answer 21

1. ionisation
2. acceleration
3. ion drift
4. detection
5. data analysis

Question 22

what are the two methods of ionisation (mass spectrometry)?

Answer 22

1. electrospray - particles gain a proton
   X(g) + H⁺ -> XH⁺(g)
2. electron bombardment - an electron is knocked off
   X(g) -> X⁺(g) + e⁻

Question 23

which method of ionisation is better for larger particles?

Answer 23

electrospray

Question 24

which method of ionisation is better for smaller particles?

Answer 24

electron bombardment

Question 25

how does the acceleration phase of mass spectrometry work?

Answer 25

an electric field accelerates ions so that they all have the same Ke

Question 26

what happens during the ion drift phase of mass spectrometry work?

Answer 26

ions enter a region with no electric field, which is also a vacuum
- lighter ions travel faster than heavier ions

Question 27

what happens during the ion detection phase of mass spectrometry work?

Answer 27

• ions reach the detector
• gain electrons from negative plate
• causes a current to flow
• the more ions of the same mass - the larger the current
• current is proportional to abundance

Question 28

what happens during the data analysis phase of mass spectrometry work?

Answer 28

flight times and size of current are analyised and recorded as a mass spectrum - mass/charge vs relative abundance

Question 29

Ke = …

Answer 29

Ke = 1/2 m v²

v = d/t

Question 30

what are the proper names for shells?

Answer 30

principal energy levels

Question 31

what are principal energy levels split up into?

Answer 31

sub-shells
s, p, d, f

Question 32

what are sub-shells split up into?

Answer 32

orbitals

Question 33

how many electrons can each orbital hold?

Answer 33

2

Question 34

what are s-sub-shells consisting of?

Answer 34

1s orbitals - 2 e

Question 35

what are p-sub-shells consisting of?

Answer 35

3p orbitals - 6e

Question 36

what are d-sub-shells consisting of?

Answer 36

5d orbitals - 10e

Question 37

what are f-sub-shells consisting of?

Answer 37

7f orbitals - 14e

Question 38

1 sub-level consists of?

Answer 38

1 x s = 2e

Question 39

2 sub-levels consists of?

Answer 39

1 x s = 2e
3 x p = 6e

8e total

Question 40

3 sub-levels consists of?

Answer 40

1 x s = 2e
3 x p = 6e
5 x d = 10e

18e total

Question 41

4 sub-levels consists of?

Answer 41

1 x s = 2e
3 x p = 6e
5 x d = 10e
7 x f = 14e

32e total

Question 42

what is the order of the orbitals in terms of energy levels?

Answer 42

1s , 2s , 2p , 3s , 3p , 4s , 3d , 4p , 4d , 4f