Bonding

Question 1

Define Ionic bonding

Answer 1

Ionic compounds are oppositely charged ions held together by electrostatic attraction.

Question 2

Ionic bonding properties

Answer 2

1. Most ionic bonds dissolve in water.
2. Conduct electricity when molten or dissolved in a solution as ion are free to move around.
3. Have high melting points as there are many, strong electrostatic forces between oppositely charged ions.

Question 3

What’s Covalent bond

Answer 3

A covalent bond is a type of chemical bond in which atoms share electrons in order to form a stable bond. Covalent bonds are formed between non-metallic elements, such as hydrogen, oxygen, nitrogen, and carbon.

Question 4

Graphite properties

Answer 4

1. Layers slide easily as there are weak forces between the layers
2. Delocalised electrons between the layers allow graphite to conduct electricity as they can carry a charge.
3. Layers are far apart in comparison to covalent bond means it has low density.
4. High melting point.
5. Insoluble, bonds are too strong to break.

Question 5

Properties of diamonds

Answer 5

1. The tightly packed, rigid arrangement allows heat to conduct well In diamonds.
2. High melting point .
3. Doesn’t conduct electricity.
4. Insoluble.

Question 6

Name the shape

Bond pair=2
Lone pair = 0
Angle= 180

Answer 6

Linear

Question 7

Name the Shape

Bond pair= 3
Lone pair = 0
Angle = 120

Answer 7

Trigonal planar

Question 8

Name the shape

Bond pair= 4
Lone pair = 0
Angle= 109.5

Answer 8

Tetrahedral

Question 9

Name the shape

Bond pair= 5
Lone pair = 0
Angle = 90

Answer 9

Trigonal bipyramidal

Question 10

Name the shape

Bond pair= 6
Lone pair= 0
Angle = 90

Answer 10

Octahedral

Question 11

Name the shape

Bond pair = 3
Lone pair = 1
Angle = 107

Answer 11

Pryramidal

Question 12

Name the shape

Bond pair= 2
Lone pair = 2
Angle = 104.5

Answer 12

Bent

Question 13

Name the shape

Bond pair= 3
Lone pair= 2
Angle= 120

Answer 13

Trigonal planar

Question 14

Name the shape

Bond pair = 4
Lone pair= 2
Angle = 90

Answer 14

Square planar

Question 15

Why do Van de Waals occur ?

Answer 15

They occur because the electrons are constantly moving around and there will be an uneven electron distribution at any given moment in time. This causes a temporary dipole within a molecule.
This temporary dipole induces a temporary dipole in a neighbouring molecule. There is an attraction between these molecules- this is temporary induced dipole-dipole attraction.

Question 16

Define Electronegativity

Answer 16

Electronegativity is the ability for an atom to attract electrons towards itself in a covalent bond

Question 17

Properties of metallic bonding

Answer 17

1. Metals are good thermal conductors as the delocalised electrons can transfer kinetic energy.
2. High melting point due to strong electrostatic attraction.
3. Insoluble .
4. Can conduct electricity.

Question 18

The bond angle around the oxygen atom in methanol is slightly smaller than the regular tetrahedral angle of 109.5.
Explain why ?

Answer 18

Lone pairs have greater repulsion than bonding pair.

Question 19

The melting point of XeF4 is higher than the melting point of PF3
Explain why the melting points of these two compounds are different
In your answer you should give the shape of each molecule, explain why each molecule has that shape and how the shape influences the forces that effect the melting point (6)

Answer 19

• Xe has 8 electrons in its outer shell, giving XeF4 4 bonding pairs of electrons and 2 lone pairs.
• Electron pairs repel as far as possible, lone pairs repel even further
• XeF4 has a square planar shape with a bond angle of 90

P has 5 electrons in its outer shell, giving PF3 3 bonding pairs of electrons that repel as far as possible and 1 lone pair that repels even further
- PF3 has the shape trigonal pyramidal, with bond angles 107.

XeF4 only has VDWs as dipoles in square planar cancel out, whereas PF3 has dipole-dipole forces
- However, XeF4 is a larger molecule with more electrons, making the VDWs very strong (also flat so can compact together to make VDWs even stronger)
- ∴ has greater electrostatic forces that require more energy to be broken than in PF3 ∴ higher melting point

Question 20

Ionic Bonding

Answer 20

A bond between metals and non-metals. The metal will donate electrons to the non-metal in order to achieve a full outer shell and achieving noble gas status. This allows the molecules to be ionised, forming attraction towards one another due to opposite charge attraction via electrostatic forces

Question 21

Ionic Lattice

Answer 21

The structure of an ionic compound. This allows the compound to be brittle and non-conductive in a solid state

Question 22

How do lone pairs affect bond angles?

Answer 22

Lone pairs repeal more than bonding pairs of electrons.
This reduces the bond angle.

Question 23

How do Van der Waals forces arise?

Answer 23

There is an uneven distribution of electrons in one molecule which induce dipole in the neighbouring molecule.
Symmetrical dipole cancel each other out.

Question 24

Explain how permanent dipole-dipole forces arise between molecules.

Answer 24

Difference in electronegativity leads to bond polarity.
- Dipoles don’t cancel out therefore the molecule has an overall permanent dipole.
- There is attraction between the δ+ (slightly positive end) on one molecule and the δ− (slightly neg

Question 25

Why does electronegativity increase along a period?

Answer 25

Same shielding but more protons (bigger nuclear charge)

Question 26

Why are ionic bonds strong?

Answer 26

Strong electrostatic attraction between positive and negative ions.

Question 27

Explain, in terms of its structure and bonding, why nickel has a high melting point.

Answer 27

Contains positive metal ions and a sea of delocalised electrons.

Question 28

Diamond and graphite are both forms of carbon. Diamond is able to scratch almost all other substances, whereas graphite may be used as a lubricant. Diamond and graphite both have high melting points. Explain each of these properties of diamond and graphite in terms of structure and bonding. Give one other difference in the properties of diamond and graphite.

Answer 28

Structure and Hardness Diamond and graphite are both giant covalent. In diamond - carbons are joined to 4 other carbon atoms, hard, because of the 3D structure, melting point is high because covalent bonds must be broken but they are very strong, diamond does not conduct electricity. In graphite - carbon atoms are joined to 3 other carbon atoms, graphite is soft as layers can slide over each other - however there are van der waals between the layers which can be easily broken, conductor of electricity

Question 29

How do you know if its a dipole-dipole or hydrogen bonding?

Answer 29

Dipole-dipole and hydrogen bonding are not the exact same thing. Hydrogen bonding is a type of dipole-dipole in which a hydrogen atom bonded to N,O, or F is attracted to lone pair on another N,O, or F while dipole-dipole is an interaction between two polar molecules.

Question 30

How do you tell if an atom is a dipole?

Answer 30

Dipole moments occur when there is a separation of charge. They can occur between two ions in an ionic bond or between atoms in a covalent bond; dipole moments arise from differences in electronegativity. The larger the difference in electronegativity, the larger the dipole moment.

Question 31

Define the term Electronegativity

Answer 31

Power of an atom to attract a pair of electron in a covalent bond

Question 32

Explain how permanent dipole arise between molecules

Answer 32

Difference in Electronegativity leads to bond polarity. (Dipoles doesn’t cancel therefore the molecules has an overall permanent dipole ) and there is an attraction between delta positive on one molecule and delta negative on another

Question 33

What is the difference between a covalent bond and an ionic bond?

Answer 33

The difference between a covalent bond and an ionic bond is that in a covalent bond, electrons are shared between atoms, whereas in an ionic bond, electrons are transferred from one atom to another. Covalent bonds are typically formed between non-metallic elements, while ionic bonds are typically formed between a metallic element and a non-metallic element.