Module 3: Periodicity

Question 1

Describe how the periodic table is arranged

Answer 1

In order of increasing atomic number

Question 2

Which groups are in the s block of the periodic table?

Answer 2

-Groups 1 and 2
-The highest energy level of the electrons are in the s orbital

Question 3

What groups are in the d block of the periodic table?

Answer 3

-Transition metals
-The highest energy level of the electrons are in the d orbital

Question 4

Which groups are in the p block of the periodic table?

Answer 4

-Groups 3,4,5,6,7 and 0
-The highest energy level of the electrons are in the p orbital

Question 5

Which groups are in the f block of the periodic table?

Answer 5

-The elements in the bottom section
-The highest energy level of the electrons are found in the f orbital

Question 6

Define the term ‘periodicity’

Answer 6

The regular, repeating pattern in the chemical and physical properties of elements

Question 7

Explain why elements in the same group have similar chemical properties

Answer 7

They have the same electron configuration

Question 8

Explain why elements are arranged in periods

Answer 8

-It shows the physical properties of elements
-E.g. state, melting point, boiling point, metals/non-metals, ionisation energy

Question 9

Define the term ‘first ionisation energy’

Answer 9

The energy required to remove one mole of electrons from one mole of gaseous atoms of an element to form one mole of gaseous 1+ ions

Question 10

Explain what is meant by the term ‘ionisation’

Answer 10

When an atom looses or gains an electron

Question 11

Define the term ‘ionisation energy’

Answer 11

The amount of energy needed to loose an electron

Question 12

State the first, second and third ionisation energy of sodium

Answer 12

1st= Na (g) —> Na+ (g) + e-
2nd= Na+ (g) —> Na2+ (g) + e-
3rd= Na2+ (g) —> Na3+ (g) + e-

Question 13

What is meant by the term ‘successive ionisation energy’?

Answer 13

It confirms how many electrons are in the outer shell

Question 14

State three factors a which affect ionisation energy

Answer 14

-Shielding
-Nuclear charge
-Atomic radius

Question 15

Why are elements arranged in groups?

Answer 15

Have similar chemical properties

Question 16

Outline the trend in atomic radius as you go across a period

Answer 16

-Atomic radius decreases
-This is due to an increased nuclear charge for the same number of shells
-The outer electrons experience greater attraction to the nucleus due to increased charge
-As a result the atomic radius is reduced

Question 17

Outline the trend in atomic radius as you go down a group

Answer 17

-Atomic radius increases
-Attraction to the nucleus decreases as more shells are added
-More shells also increases shielding
-so nuclear attraction is reduced and atomic radius increases

Question 18

Outline the trend in atomic radius as you go down a group

Answer 18

-Atomic radius increases
-Attraction to the nucleus decreases as more shells are added
-More shells also increases shielding
-so nuclear attraction is reduced and atomic radius increases

Question 19

Outline the trend in first ionisation energy as you go along a period

Answer 19

-First ionisation energy increases
-Due to decreasing atomic radius
-and greater electrostatic forces of attraction

Question 20

Outline the trend in first ionisation energy as you go down a group

Answer 20

-First ionisation energy decreases
-Due to increasing atomic radius and electron shielding
-which reduces the effect of electrostatic forces of attraction

Question 21

State the trend in nuclear charge as you go across a period

Answer 21

Nuclear charge increases

Question 22

State the trend in nuclear attraction as you go across a period

Answer 22

Nuclear attraction increases

Question 23

State the trend in nuclear attraction as you go down a group

Answer 23

Nuclear attraction decreases

Question 24

Outline the general trend in first ionisation energy as you go across period 2

Answer 24

-First ionisation enthalpy increases due to:
-nuclear charge increases
-atomic radius decreases
-so nuclear attraction decreases
-more energy is needed to remove the first electron

Question 25

Outline the general trend in first ionisation energy across period 3

Answer 25

-First ionisation energy increases due to:
-nuclear charge increases
-atomic radius decreases
-so nuclear attraction decreases
-more energy is needed to remove the first electron

Question 26

State the general exceptions to the trend in first ionisation energy in period 2

Answer 26

Boron and oxygen

Question 27

Explain how boron is an exception to this trend (period 2)

Answer 27

-Boron has a lower first ionisation energy than expected
-due to the energy difference between the 2s and 2p sub-shells
-the electron is being removed from a higher energy level that is further from the nucleus
-as there is less nuclear attraction (because it is further away) less energy is needed to remove the first electron

Question 28

Explain how oxygen is an exception to this trend (period 2)

Answer 28

-Oxygen has a lower first ionisation energy than expected
-due to the repulsion within the 2p orbital when two electrons with opposite spin are in the same orbital
-this repulsion means an electron is removed more easily therefore less energy is needed to remove the first electron

Question 29

State the general exceptions to the trend in first ionisation energy in period 3

Answer 29

Aluminium and sulfur

Question 30

Explain how aluminium is an exception to this trend (period 3)

Answer 30

-Aluminium has a lower first ionisation energy than expected
-due to the energy difference between the 3s and 3p sub-shells
-the electron is being removed from a higher energy level that is further from the nucleus
-as there is less nuclear attraction (because it is further away) less energy is needed to remove the first electron

Question 31

Explain how sulfur is an exception to this trend (period 3)

Answer 31

-Sulfur has a lower first ionisation energy than expected
-due to the repulsion within the 3p orbital when two electrons with opposite spin are in the same orbital
-this repulsion means an electron is removed more easily therefore less energy is needed to remove the first electron

Question 32

Define the term ‘shielding’

Answer 32

Inner electrons blocking the positive charge on the nucleus

Question 33

Define the term ‘nuclear charge’

Answer 33

The positive charge on the nucleus (the number of protons)

Question 34

Define the term ‘atomic radius’

Answer 34

The radius of an atom

Question 35

What is metallic bonding?

Answer 35

The strong electrostatic attraction between cations (positive ions) and delocalised electrons

Question 36

State three giant metallic structures in period 3

Answer 36

Sodium, magnesium, aluminium

Question 37

Describe the trend in melting and boiling point across period 3 giant metallic structures (sodium, magnesium and aluminium)

Answer 37

Melting and boiling points increase

Question 38

Outline why melting and boiling point increases from sodium to aluminium (period 3)

Answer 38

-The charge on the ion increases from +1 to +3 meaning the number of delocalised electrons increases
-so the strength of metallic bonding increases
-more energy is needed to break the strong metallic bonding
-melting and boiling point increases

Question 39

Describe the structure and bonding in giant covalent structures

Answer 39

Atoms are joined together by covalent bonds

Question 40

State which element in period 3 has a giant covalent structure

Answer 40

Silicon

Question 41

Describe the structure and bonding in silicon

Answer 41

-A giant covalent structure
-Each silicon is bonded to four other silicon atoms

Question 42

Outline the melting point of silicon

Answer 42

-High melting point
-Lots of energy is needed to break the strong covalent bonds to melt silicon

Question 43

State three examples of giant covalent lattices of carbon

Answer 43

Diamond, graphite and graphene

Question 44

Describe the structure and bonding in diamond

Answer 44

-Giant covalent lattice
-Each carbon atom is bonded to four other carbon atoms
-Has a very high melting point

Question 45

Describe the structure and bonding in graphite

Answer 45

-Giant covalent lattice
-Each carbon atom is bonded to three other carbon atoms atoms in flat sheets
-This means there is one delocalised electron per atom which can move between layers so graphite can conduct electricity
-There are London forces between layers (these are weak intermolecular forces) which allows the layers you slide over each other
-This makes graphite a good lubricant

Question 46

Describe the structure and bonding in graphene

Answer 46

-Made of a single layer of carbon atoms that are bonded together in a repeating patterns