Chapter 7 (Approved)

Question 1

What did Mendeleev do with the periodic table?

Answer 1

He arranged them in order of atomic mass
He lined up elements in groups with similar properties
He predicted properties of the missing elements from group trends

Question 2

Periodicity

Answer 2

A repeating trend in properties across different periods

Question 3

What properties display periodicity?

Answer 3

Electron configuration, ionisation energy, structure, melting points

Question 4

What is the chemistry of each element determined by?

Answer 4

Electron configuration, particularly the outer shell

Question 5

Electron configuration trend across a period

Answer 5

Across each period, it starts with an electron in a new highest energy shell, then the s sub-shell fills with 2 electrons and the p sub-shell fills with 6 electrons

Question 6

What does ionisation energy measure?

Answer 6

How easily an atom loses electrons to form positive ions

Question 7

First ionisation energy

Answer 7

The energy required to remove one electron from each atom in one mole of gaseous atoms

Question 8

Factors affecting ionisation energy

Answer 8

Atomic radius: The greater the radius, the weaker the electrostatic attraction
Nuclear charge: The more protons, the greater the electrostatic attraction
Electron shielding: The more inner shells, the weaker the electrostatic attraction

Question 9

How many ionisation energies does an element have?

Answer 9

As many as there are electrons

Question 10

What does a large increase in successive ionisation energies suggest and why?

Answer 10

It suggest that the electron must’ve been removed from a different shell, because the outer electron is closer to the nucleus, and has less inner shells, increasing electrostatic attraction between the electron and the nucleus which requires more energy to overcome

Question 11

Trend in first ionisation energy down a group and why

Answer 11

Decreases down a group, although nuclear charge increases, the effect is outweighed by increased atomic radius and electron shielding

Question 12

Trend in first ionisation energy across period and why

Answer 12

Increases across a period, due to increased nuclear charge leading to decreased atomic radius, and the electron shielding doesn’t change across a period

Question 13

Where does first ionisation energy drop across a period?

Answer 13

1. Between the 2nd s sub-shell element and the 1st p sub-shell element
2. Between the 3rd and 4th p sub-shell element

Question 14

why does first ionisation energy drop between the 2nd s sub-shell element and the 1st p sub-shell element?

Answer 14

Because the electrons in the p sub-shell are slightly easier to remove because the p electrons are higher in energy and slightly shielded by the s electrons

Question 15

Why does the first ionisation energy drop between the 3rd and 4th p sub-shell element?

Answer 15

There are initially 3 elcetrons in the p sub-shell, one in each orbital, but the 4th electron doubly fills the first p orbital, and the two electrons in the same orbital repel each other, which makes the electron require less energy to remove

Question 16

What is the constant property of all metals

Answer 16

The ability to conduct electricity

Question 17

Metallic bonding

Answer 17

The strong electrostatic attraction between metal cations and delocalised electrons

Question 18

What is the ratio of positive to negative charges in a giant metallic lattice?

Answer 18

1:1, the charges are balanced.
e.g. If the metal ions have a 2+ charge, there will be double the number of electrons as cations

Question 19

Properties of metals (4)

Answer 19

• Strong metallic bonds (due to electrostatic attraction between positive ions and delocalised electrons)
• High electrical conductivity ( In solid and liquid state due to its delocalised electrons)
• High melting and boiling points (due to strong metallic bonds)
• Insoluble in water

Question 20

Diamond (3)

Answer 20

Tetrahedral structure
Each carbon atom forms 4 covalent bonds
Cannot conduct due to lack of delocalised electrons

Question 21

Graphite (3)

Answer 21

Planar structure
Each carbon forms 3 covalent bonds
4th outer shell electron is delocalised
Can conduct electricity when solid due to delocalised electrons

Question 22

Properties of giant covalent structures (3)

Answer 22

High melting and boiling points due to strong covalent bonds
Insoluble in most solvents due to strong covalent bonds which can’t be broken down by interacting with solvents
Non-conductors due to lack of delocalised electrons except from graphene and graphite

Question 23

Trend in melting points across periods

Answer 23

Increases from group 1 to 4, decreases sharply between group 4 and 5 and remains low until group 0

Question 24

Why does melting point sharply decrease from group 4 to 5?

Answer 24

Due to a change from giant structures, which have strong forces to overcome and therefore high melting points, and simple molecular structures which have weak forces to overcome so low melting points