Topic 1

Question 1

Isotope

Answer 1

Atoms of the same element but different masses, with the same number of protons but different numbers of neutrons

Question 2

Relative isotopic mass

Answer 2

The mass of an atom of a single isotope relative to 1/12th of the mass of a C12 atom.

Question 3

Relative atomic mass

Answer 3

The weighted mean mass of an atom of an element relative to 1/12th of the mass of a C12 atom, taking into account isotopic abundances

Question 4

First ionisation energy

Answer 4

The amount of energy required to remove an electron from each atom in 1 mole of gaseous atoms of an element to form 1 mole of gaseous ions of that element (KJ/mol)

Question 5

Effective nuclear charge

Answer 5

The net positive charge experienced by an electron in an atom.
Varies depending on the number of protons and the extent of electron shielding.

Question 6

Factors affecting ionisation energy

Answer 6

Number of protons
-stronger electrostatic attraction, increases IE
Number of shells
-greater distance between the outermost electron and nucleus, less attraction, decreases IE
-increased electron shielding by inner electron shells, greater repulsion, decreases IE

Question 7

Trends in ionisation energy

Answer 7

Decrease down the group
Increase across a period
Increase in successive ionisation energies

Question 8

Exceptions to the ionisation energy trend

Answer 8

Decreases from group 2-3
(for Be and B)
Electron lost from 3s subshell in group 2 and 3p subshell in group 3. 3s is closed to nucleus than 3p, takes less energy to remove electron from 3p.

Decreases from group 5-6
(for P and S)
Outer shell of P is 3p3, so each electron has its own orbital. Outer shell of S is 3p4, so there is a pair of electrons in one of the 3p orbitals. Repulsion between this pair of electrons means less energy is needed to remove an electron from S.

Question 9

Exceptions to normal electronic configuration

Answer 9

Chromium and copper. One electron moves from 4s to 3d.

Question 10

Sub-shells

Answer 10

S: 1 orbital, 2 electrons
P: 3 orbitals, 6 electrons
D: 5 orbitals, 10 electrons
F: 7 orbitals, 14 electrons

Question 11

Periodicity

Answer 11

A repeating pattern across different periods.

Question 12

Trend in melting points across a period

Answer 12

Increases group 1 to group 3
- strength of metallic bonding increases

Highest group 4
-macromolecules with lots of strong covalent bonds that require a lot of thermal energy to break

Lower group 5-7
-simple molecules with weak intermolecular forces that require little thermal energy to overcome

Lowest group 8
-exist as single atoms with weak interatomic forces that require little thermal energy to overcome

Question 13

Emission specrum

Answer 13

The spectrum of frequencies of EM radiation emitted due to an atom or molecule transitioning from a higher to lower energy state

Question 14

Orbital definition

Answer 14

A region within an atom that can hold up to 2 electrons with opposite spins

Question 15

How do flame colours arise?

Answer 15

Heating excites the electrons to higher energy levels
Electrons fall back to lower energy levels
Emitting light
Moving between different levels in different elements means different amounts of energy is emitted which corresponds to different colours of light.
If there is no colour, the energy released is outside of the visible spectrum.

Question 16

Evidence for quantum shells

Answer 16

Pattern of successive ionisation energies

Unique emission spectrums of certain frequencies