Atomic Structure

Question 1

What is the atomic number

Answer 1

Number of protons

Question 2

How is mass number calculated

Answer 2

Number of protons + number is neutrons

Question 3

What is an isotope

Answer 3

Different forms of the same element

Same number of protons but different neutrons

Question 4

Orbitals

Answer 4

1s2 2s2 2p6 3s2 3p6 4s2 3d10

Question 5

Does 3d or 4s have a higher energy

Answer 5

3d

Question 6

What is an orbital

Answer 6

A region around the nucleus that can hold up to two electrons

Question 7

Explain why chromium does not fit the trend for electron configuration

Answer 7

It only has one electron in its 4s orbital before filling 3d

Question 8

Explain why cooper does not for the trend

Answer 8

It only has one electron in its 4s orbital before filling 3d

Question 9

Two types of ionisation for a mass spec

Answer 9

1. Electron impact. Electron gun knocks off one electron from each particle to form 1+ ion
2. Electron spray. Sample dissolved in volatile solvent and injected through a fine needle which is attached to a positive terminal of a high voltage power supply and particles gain a proton from the solvent as they leave the needle

Question 10

When would you use each type of ionisation in mass spec

Answer 10

Electron impact used with low formula mass

Electron spray used with high formula mass

Question 11

How does time of flight mass spec work

Answer 11

Acceleration- positive ions towards a negatively charged plate
Ion drift- ion passes through a hole in plate, form a beam with constant energy, travel alone a tube to detector
Detection- positive ions pick up electrons, time of flight is recorded

Question 12

Define first ionisation energy

Answer 12

The energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous 1+ ions