Chapter 1 - Atomic Structure

Question 1

Define the term 1st ionisation energy.

Answer 1

The energy required to remove 1 mole of electrons from 1 mole of gaseous atoms.

Question 2

What is the charge of a proton, neutron and electron?

Answer 2

• Proton = +1
• Neutron = 0
• Electron = -1

Question 3

What is the mass of a proton, neutron and electron?

Answer 3

• Proton = 1
• Neutron = 1
• Electron = 1/2000

Question 4

List the orbitals in order of lowest to highest energy.

Answer 4

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

Question 5

What are isotopes?

Answer 5

Versions of atoms that have the same number of protons but a different number of neutrons.

Question 6

What are the two types of ionising in a mass spectrometer?

Answer 6

1) Electron gun

2) Electrospray

Question 7

How does the electron gun ionise atoms?

Answer 7

The electron gun fires high energy electrons at the atom in order to knock an electron off, turning it into a positive ion.

Question 8

What is the equation for ionising with an electron gun?

Answer 8

M(g) + e- ➡️ M+(g) + 2e-

Question 9

What are the four stages of a mass spectrometry?

Answer 9

1) Ionising
2) Acceleration
3) Ion drift
4) Detection

Question 10

What happens when an atom is ionised with electrospray?

Answer 10

Hydrogen ions are added to the substance from a solvent using a high voltage. The addition of a proton makes it a positive ion.

Question 11

What equation represents electrospray ionisation?

Answer 11

M(g) + H+ ➡️ MH+(g)

Question 12

What happens in the acceleration stage in a mass spec?

Answer 12

The positive ions are attracted to negative plates, focussed into a beam meaning that they all have the same kinetic energy when entering the ion drift.

Question 13

What happens in the ion drift stage of a mass spec?

Answer 13

Ions move at varying speeds depending on their mass. Lighter ions move faster and heavier move slower.

Question 14

What happens during the detection stage in a mass spec?

Answer 14

As soon as ions hit the detector an electron is added making it a neutral atom. When the electron is added it produces an electric current which is bigger if there are more ions of the same mass. The mass spec picks up the electric current.

Question 15

What are the two axis on a mass spec graph?

Answer 15

Y axis = relative abundance

X axis = mass/charge

Question 16

Which atoms can only hold 1 electron in their 4s orbital?

Answer 16

Copper (Cu)

Chromium (Cr)

Question 17

When drawing a mass spec graph what would you always list?

Answer 17

The possible ions.
Example : *take up 50%
Br79 + Br79
Br79 + Br81*
Br81 + Br79*
Br81 + Br81

Question 18

How many electrons can s orbitals hold?

Answer 18

2

Question 19

How many electrons can p orbitals hold?

Answer 19

6

Question 20

How many electrons can d orbitals hold?

Answer 20

10

Question 21

What is the equation for the 1st ionisation energy of an atom?

Answer 21

M(g) ➡️ M+(g) + e-

Question 22

What are the three factors that affect the Ionisation Energy of an atom?

Answer 22

1) nuclear charge
2) atomic/ionic radius
3) shielding

Question 23

Define the term “nuclear charge”

Answer 23

The amount of protons in the nucleus which are attracting the electrons.

Question 24

Define the term “atomic radius”

Answer 24

The distance between the nucleus and the electron which is farthest away.

Question 25

What is the general trend for atomic radius as you go across a period?

Answer 25

It DECREASES because electrons are being added to the same energy level while protons are being added to the nucleus.

Question 26

Define the term “shielding”

Answer 26

The number of electrons between the nucleus and the electron furthest away.

Question 27

What is the equation for the 2nd ionisation energy?

Answer 27

M+(g) ➡️ M2+(g) + e-

Question 28

Why does the 2nd ionisation of an atom require more energy than the 1st?

Answer 28

Because the radius is smaller and the shielding is decreasing.

Question 29

Why does going between main energy levels cause a massive surge in energy?

Answer 29

Because the electrons are getting much closer to the nucleus. (Radius⬇️)

Question 30

What is the general trend of 1st ionisation energies down a group?

Answer 30

It INCREASES (more shielding).

Question 31

On what atoms are the blips for 1st ionisation energies across period 2?

Answer 31

On Aluminium (blip 1) and Sulphur (blip 2)

Question 32

Why does Aluminium have a lower ionisation energy than Magnesium?

Answer 32

Because the 3s electron that is being removed is experiencing mutual repulsion and a result of being part of a pair of electrons.

Question 33

Why does Sulphur have a lower ionisation energy that Phosphorus?

Answer 33

Because the 3p electron being removed is higher energy.

Question 34

What is the “relative formula mass” of an atom?

Answer 34

The average mass of an atom compared to 1/12th the mass of a carbon 12 atom.