Topic 1

Question 1

what is the definition of atomic number?

Answer 1

the number of protons in the nucleus of an atom

Question 2

what is the definition of mass number

Answer 2

the number of protons and neutrons in a nucleus

Question 3

what is the definition of relative isotopic mass

Answer 3

average mass of an atom of an isotope relative to 1/12th the mass of an atom of carbon-12

Question 4

what is the definition of relative atomic mass

Answer 4

the relative mass of atoms compared to the mass of an atom of carbon-12

Question 5

how can mass spectrometry be used to determine the relative molecular mass of a molecule

Answer 5

the relative molecular mass of the molecular ion would be the relative molecular mass of the molecule
the molecular ion is the one the furthest to the right on mass spectra

Question 6

how are ionisation energies influenced by the number of protons

Answer 6

nuclear charge increases with increasing atomic number
greater attractive forces between the nucleus and outer electrons
more energy required to overcome these attractive forces when removing an electron

Question 7

how ionisation energies are influenced by electron shielding and the electron sub-shell from which the electron is removed

Answer 7

Electrons further away from the nucleus are less attracted to it
electrons in full inner shells repel electrons in outer shells -> prevents them from feeling the full nuclear charge
paired electrons in the same orbital in a subshell repel eachother more than electrons in different orbitals -> easier to remove electron

Question 8

what are the reasons for general increase in first ionisation energy across a period

Answer 8

due to increase in nuclear charge
greater attraction between outer electron and nucleus
more energy required to remove electron

Question 9

how do electrons fill subshells

Answer 9

electrons fill subshells singly before pairing up
two electrons in the same orbital have to have opposite spins

Question 10

why does ionisation energy fall at aluminium across period 3

Answer 10

this is because aluminiums outer electron is in a 3p orbital rather than a 3s
3p further from nucleus -> extra shielding

Question 11

why does ionisation energy fall at sulphur

Answer 11

extra repulsion between pair of electron in the same orbital
easier to remove e-

Question 12

why does mtp/bpt increase

Answer 12

stronger intermolecular forces

Question 13

what should you do for a mass spec question that asks you to give the mass/charge ratio f the ions responsible for the molecular ion peaks of a molecule

Answer 13

for this kind of question you write all possible combinations of the ions to make the molecular ion using the isomers given