periodicity

Question 1

How are elements arranged in the periodic table

Answer 1

They are arranged in the order of increasing atomic number

Question 2

What is a period on a periodic table

Answer 2

The horizontal rows in the periodic table

Question 3

What is a group on a periodic table

Answer 3

The vertical columns

Question 4

What is meant by periodicity

Answer 4

The repeating trends in chemical and physical properties

Question 5

What change happens across each period

Answer 5

Elements change from metals to non-metals

Question 6

How can the electron configuration be written in short?

Answer 6

The noble gas before the element is used to abbreviate

Question 7

Define the first ionisation energy

Answer 7

The energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of 1+ gaseous ions

Question 8

What are the factors that affect ionisation energy

Answer 8

• Atomic radius
• Nuclear charge
• Electron shielding

Question 9

Why does first ionisation energy decrease between groups 2 to 3

Answer 9

• Decrease between 2 to 3 because in group 3 the outermost electrons are in p orbitals whereas in group 2 they are in s orbital, so the electrons are easier to be removed

Question 10

Why does the first ionisation energy decrease between groups 5 to 6

Answer 10

• Decrease between 5 and 6 is due to group 5 electrons and in group 6 outermost electrons are spin paired with some repulsion, therefore the electrons are easier to remove

Question 11

Explain what happens to the first ionisation energy across a period

Answer 11

• The ionisation energies increase
• Nuclear attraction increases because the number of protons increases which increases the nuclear attraction
• The atomic radius decreases because the electrons are pulled closer to the nucleus
• Similar shielding and distance from nucleus marginally decreases

Question 12

Explain what happens to the first ionisation energy down a group

Answer 12

• Ionisation energy decreases
• Down a group atomic radius increases
• The number of electrons increases so shielding increases
• Atomic radius increases so the outer electrons are further away from the nucleus which reduces nuclear attraction

Question 13

Why do successive ionisation energies increase within each shell?

Answer 13

• Because electrons are being removed from an increasingly positive ion and there’s less repulsion amongst remaining electrons
• So the electrons are held more strongly by the nucleus.

Question 14

Define metallic bonding

Answer 14

Metallic bondingis theelectrostatic forceof attraction between thepositive metal ionsand thedelocalised electrons

Question 15

Describe metallic bonding

Answer 15

• The electrons in the outermost shell of a metal atom are delocalised
• The metal cations are electrostatically attracted to the delocalised negative electrons
• They form a lattice of closely packed cations in a sea of delocalised electrons.

Question 16

What affects the strength of a metallic bond

Answer 16

1. The number of protons/ Strength of nuclear attraction
2. Number of delocalised electrons per atom
3. Size of ion

Question 17

Describe how metallic bonding explains the properties of metals

Answer 17

1. They are malleable and ductile due to no bonds holding specific ions together, the metal ions can slide past each other when the structure is pulled
2. Good thermal conductor because delocalised electrons can pass kinetic energy to each other
3. Good electrical conductors because the delocalised electrons can move and carry a charge
4. Insoluble except in liquid metals because of the strength of the metallic bond.

Question 18

Describe the properties of a giant metallic structure

Answer 18

1. High melting and boiling point due to strong electrostatic forces between positive ions and sea of delocalised electrons
2. Insoluble in water
3. Good conductor of electricity because delocalised electrons can move through the structure, it can conduct when solid.
4. Malleable as the positive ions in the lattice are identical so planes of ions can slide over one another

Question 19

Define giant covalent lattices

Answer 19

Giant covalent lattices are networks of covalently bonded atoms.

Question 20

Why can carbon form giant covalent lattices?

Answer 20

Carbon atoms can form giant covalent lattices because they can each form four strong covalent bonds

Question 21

What are allotropes?

Answer 21

Allotropes are different forms of the same element, in the same state

Question 22

List the allotropes of carbon

Answer 22

1. Diamond
2. Graphite
3. Graphene

Question 23

Describe the structure of diamond

Answer 23

• In diamond, each carbon atom is covalently bonded to 4 other carbon atoms
• The atoms are arranged in a tetrahedral shape - a crystal lattice structure.

Question 24

Describe the properties of diamond

Answer 24

• Diamond has a very high melting point
• Diamond is extremely hard
• A good thermal conductor because vibrations travel easily through the stiff lattice
• It can’t conduct electricity because all the outer electrons are held in localised bonds
• It won’t dissolve in any solvent

Question 25

Describe the structure of graphite

Answer 25

- The carbon atoms are arranged in sheets of flat hexagons covalently bonded with 3 bonds each - The fourth outer electron of each carbon is delocalised between the sheets of hearings.

Question 26

Describe and explain the properties of graphite

Answer 26

- Weak forces between the layers in graphite are easily broken, so the sheets can slide over each other - Can conduct electricity due to the delocalised electrons in graphite that aren't attached to a carbon atom and are free to move along the sheets and carry an electrical charge - Lightweight and strong because the layers are far apart compared to the length of covalent bonds, so it is less dense. - Very high melting point due to strong covalent bonds in the hexagon sheets - Insoluble in any solvent because the covalent bonds in the sheet are too strong to break

Question 27

Describe silicon

Answer 27

Silicon forms a crystal lattice structure with similar properties to carbon, each silicon atom is able to form 4 strong, covalent bonds.

Question 28

Describe graphene

Answer 28

Graphene is a sheet of carbon atoms joined together in hexagons, the sheet is 1 atom thick making it a 2-dimensional compound.

Question 29

Describe the properties of graphene

Answer 29

- It is an **electrical conductor** due to the **delocalised electrons** that are free to move along the sheet - **Strong** due to the delocalised electrons strengthening the **covalent bonds** between atoms - **Transparent** and light because it is a **single layer**

Question 30

What can graphene be used for?

Answer 30

1. High-speed electronics 2. Aircraft technology 3. Touchscreens on smartphones

Question 31

Describe simple molecular structures

Answer 31

- They contain only a few atoms - The **covalent bonds** between atoms in the molecule are strong, the melting and boiling points depend on **induced dipole-dipole forces** between their molecules - they are weak and have low melting and boiling points