Atomic structure

Question 1

Atomic number

Answer 1

Number of protons in a nucleus

Question 2

Mass number

Answer 2

Number of protons + number of neutrons in a nucleus

Question 3

Proton

Answer 3

• relative mass of 1

- charge of +1

Question 4

Neutron

Answer 4

• relative mass of 1

- charge of 0

Question 5

Electron

Answer 5

• relative mass of 1/1840

- charge of -1

Question 6

Isotopes

Answer 6

Atoms of the same element with different numbers of neutrons (so different mass numbers)

Question 7

Relative isotopic mass

Answer 7

Relative mass of an atom of an isotope compared to 1/12th the mass of a carbon 12 atom

Question 8

Relative atomic mass

Answer 8

Weighted average mass of an atom of an element compared to 1/12th the mass of a carbon 12 atom

Question 9

Mass spectrometry

Answer 9

Sample of molecules are turned into positive ions and each ion’s mass/charge ratio and abundance are recorded

Question 10

Molecular ion peak

Answer 10

The largest peak on the mass spectrum, which has a m/z ratio equal to the relative molecular mass

Question 11

Relative formula mass

Answer 11

Mass (in grams) per mole of a chemical

Question 12

First ionisation energy

Answer 12

Energy taken to remove 1 mole of electrons from of 1 mole of of gaseous atoms of an element to form 1 mole of gaseous + ions

Question 13

Why ionisation energy increases across a period

Answer 13

• higher nuclear charge
• smaller atomic radius
• more attraction between nucleus and outer shell

Question 14

Why ionisation energy decreases down a group

Answer 14

• more electron shielding
• larger atomic radius
• less attraction between nucleus and outer shell

Question 15

Why ionisation energy of group 6 is lower than group 5

Answer 15

• the first p orbital gains a second electron
• the electrons in the orbital repel each other
• this makes it easier to remove one of them

Question 16

Why ionisation energy of group 3 is lower than group 2

Answer 16

• the p sub shell gains its first electron
• it is at higher energy
• less energy is needed to remove the electron

Question 17

Electron orbital

Answer 17

A region of an atom that can hold 2 electrons of opposite spin

Question 18

s orbital

Answer 18

• one in every shell

- sphere shaped

Question 19

p orbital

Answer 19

• three in each shell from period 2 onwards

- dumbbell shaped

Question 20

How to find the amount of electrons in a shell / sub shell

Answer 20

Count across the periodic table

Question 21

How a sub shell fills with electrons

Answer 21

Each orbital in the sub shell gains 1 electron, then they start pairing up

Question 22

Which sub shell fills first, 3d or 4s?

Answer 22

4s because it at lower energy

Question 23

Sub shells fill in what order?

Answer 23

They fill in order of increasing energy:

1s 2s 2p 3s 3p 4s 3d

Question 24

Why do Cr and Cu only have one electron in 4s?

Answer 24

The electron is moved into 3d to ‘complete’ it, making the arrangement more stable