1 - Atomic Structure and the Periodic Table

Question 1

Definition of relative atomic mass

Answer 1

The average mass of one atom compared to one twelfth of the mass of one atom of carbon-12

Question 2

Definition of relative isotopic mass

Answer 2

The mass of one atom of an isotope compared to one twelfth of the mass of one atom of carbon-12

Question 3

Definition of relative molecular mass

Answer 3

The average mass of a molecule compared to one twelfth of the mass of one atom of carbon-12

Question 4

How to calculate R.A.M on a mass spectrometer

Answer 4

(Sum of isotopic mass x % abundance) / 100 or

(Sum of isotopic mass x relative abundance) / total relative abundance

Question 5

What are the isotopes for Cl and Br

Answer 5

Cl - 35 and 37

Br - 79 and 81

Question 6

How to find Mr of molecule on mass spectrum?

Answer 6

The molecular ion peak is found at the highest peak as this is the entire fragment

Question 7

2 Uses of Mass Spectrometers

Answer 7

Drug testing

Radioactive dating of fossils

Question 8

Definition of first ionisation energy

Answer 8

The energy required to remove an electron from each atom in one mole of atoms in the gaseous state to produce one mole of positively charged ions

Question 9

Equation for the first ionisation energy

Answer 9

H(g) –> H+(g) + e-

Question 10

Definition of second ionisation energy

Answer 10

Energy required to remove an electron from each singly charged positive ion in one mole of positive ions in the gaseous state.

Question 11

Equation for the second ionisation energy

Answer 11

H+(g) –> H2+(g) + e-

Question 12

3 Main factors affection ionisation energy

Answer 12

1. Attraction of the nucleus (no. of protons)
2. Distance of electrons from nucleus (size of atom)
3. Shielding (Repelling of electrons in lower energy levels)

Question 13

How many electrons do each sub shell fill?

Answer 13

S - 2
P - 6
D - 10
F - 14

Question 14

What is the order of increasing energy of the sub energy levels?

Answer 14

1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p

Question 15

How is the Periodic table split into blocks of energy levels?

Answer 15

S - D - P

F

Question 16

What shape are S sub-levels?

Answer 16

Spherical

Question 17

What shape are P sub-levels?

Answer 17

Dumbell Shaped

Question 18

Define Hund’s rule

Answer 18

Electrons will occupy the orbitals singly before pairing

Question 19

Define The Pauli Exclusion Principle

Answer 19

Two electrons cannot occupy the same orbital unless they have opposite spins.

Question 20

What is the atomic radius trend across the periods?

Answer 20

Atomic radii decreases across a period due to the increased number of protons, which creates greater attraction for electrons which are in the same shell with similar shielding.

Question 21

What is the 1st ionisation energy trend across the periods?

Answer 21

1st ionisation energy increases as the number of protons is increased and electrons are in the same shell.
Exceptions -
Small drop between Mg and Al, Mg’s outer electron in 3s whereas Al has its in 3p
Small drop between Phosphorus and Sulphur, Sulphur has slight repulsion between its two paired up electrons in the 3p orbital so its easier to remove

Question 22

Trend in melting and boiling points across period

Answer 22

Na, Mg, Al - Strong metallic bonding (Giant Lattice) - gets stronger as more electrons are added to sea of electrons
Si - Macromolecular (Giant Lattice) - many strong covalent bonds between atoms - very high mp + bp
Cl2, S8, P4 - simple molecular - weak London Forces - S8 has higher mp than P4 because it has more electrons and therefore stronger London Forces.
Noble gases are monoatomic and have weak London Forces.