Atomic Structure

Question 1

Ratios of 79Br to 81Br

Answer 1

1:1

Question 2

Ratios of 35Cl to 37Cl

Answer 2

3:1

Question 3

What’s the electron arrangement of Chromium, Cr?

Answer 3

1s2 2s2 2p6 3s2 3p6 4s1 3d5

Instead of 4s2, 3d4

Question 4

Why is the electron arrangement of Chromium unexpected?

Answer 4

Because by keeping the electrons singular, it is more energetically stable, and has reduced repulsion (no pairs, minimum repulsion)

Question 5

What is the electron arrangement of Copper, Cu?

Answer 5

1s2 2s2 2p6 3s2 3p6 4s1 3d10

Not 4s2 3d9

Question 6

Two rules about filling up electron orbitals:

Answer 6

Electrons enter the lowest energy orbital available (Aufbau)

Electrons prefer to occupy orbitals on their own and only pair up when no empty orbitals of the same energy are available (Hund’s rule)

Question 7

What is the Aufbau principle?

Answer 7

Electrons enter the lowest energy orbital available

Question 8

What’s Hund’s rule?

Answer 8

Electrons prefer to occupy orbitals on their own and only pair up when no empty orbitals of the same energy are available.

Question 9

Rule about removing electrons from orbitals:

Answer 9

Electrons in the highest energy levels lost first, but from 4s before 3d.

Question 10

Ionisation energy down a group

Answer 10

Decreases (shielding and atomic radius increases - less attraction between outer electron and nucleus)

Question 11

Ionisation energy across a period

Answer 11

Increases (shielding remains, increased nuclear charge)

Question 12

Ionisation energy

Answer 12

Energy required to remove one electron from each atom in a mole of gaseous atoms

Question 13

Relative atomic mass definition

Answer 13

The ratio of the average mass of one atom of an element to 1/12th of the mass of one atom of carbon-12

Question 14

Relative molecular mass

Answer 14

The ratio of the average mass of one molecule to 1/12th of the mass of one atom of carbon-12

Question 15

Relative isotopic mass

Answer 15

The ratio of the average mass of one atom of an isotope of an element to 1/12th of the mass of one atom of carbon-12

Question 16

What is the avogadro constant?

Answer 16

The number of particles in a mole

Question 17

What does everything stand for in pV = nRT

Answer 17

Pressure Pa, volume m^3, moles, temperature K

Question 18

Empirical formula

Answer 18

The simplest whole number ratio of atoms of each element in a compound

Question 19

Molecular formula

Answer 19

The actual number of atoms of each element in a compound

Question 20

Percentage atom economy

Answer 20

Molecular mass of desired product/ sum of molecular masses of all reactants x 100

Question 21

Advantages of high atom economy:

Answer 21

Better for the environment - produce less waste that would need to be disposed of safely

Make more efficient use of raw materials - they are more sustainable (use up natural resources more slowly)

Less expensive - less on treating waste and less on separating desired and waste products

Question 22

Ionic bonding involves:

Answer 22

Electrostatic forces of attraction between oppositely charged ions in a lattice

Question 23

What is a co-ordinate (dative covalent) bond?

Answer 23

Contains a shared pair of electrons with both electrons supplies by one atom (shown by an arrow pointing away from the donor atom)