Bonding (Not finished)

Question 1

What are ionic bonds

Answer 1

Strong electrostatic forces of attraction between oppositely charged ions

Question 2

What are covalent bonds

Answer 2

Electrostatic force of attraction between a shared pair of electrons and both the nuclei of the 2 atoms

Question 3

What is metallic bonding

Answer 3

Strong electrostatic forces of attraction between the metal cation and the sea of delocalised electrons

Question 4

What is electronegativity

Answer 4

The ability of an atom to attract a pair of electrons in a covalent bond

Question 5

What happens when there is a big difference in electronegativities

Answer 5

Electrons are transferred from the element of low electronegativity to the element of high electronegativity and the bonding is ionic

Question 6

What happens when both atoms have medium/high electronegativities and there is a small difference in electronegativities

Answer 6

The electron pair is shared fairly evenly between the two elements and the bonding is covalent

Question 7

What happens when both atoms have a low electronegativity and there is only a small difference in electronegativity values

Answer 7

Metallic bonds are formed

Question 8

What order does the gradual change in type of bonding go between ionic and covalent

Answer 8

Ionic bonds
Polarised ions
Polar molecules
Covalent bonds

Question 9

What are polarised ions

Answer 9

Electron clouds in ions become distorted and lop-sided resulting in partial sharing of electrons

Question 10

What are polar molecules

Answer 10

One end of the molecule is slightly more negative compared to the other

Question 11

What structure do ionic compounds have

Answer 11

Giant ionic lattice

Question 12

What happens when ions lose/gain electrons to have a full outer shell

Answer 12

Both elements gain a noble gas electronic structure which confers greater stability

Question 13

What do co-ordinations mean
E.g: Sodium Chloride has a 6:6 co-ordination

Answer 13

Each ion is surrounded by X amount of the other element’s ions
E.g: Each sodium ion is surrounded by 6 chloride ions and each chloride ion is surrounded by 6 sodium ions

Question 14

Why do ionic compounds have high melting and boiling points

Answer 14

Ionic bonds are very strong and it takes a lot of energy to overcome them. This means that ionic compounds are solid at room temperature too

Question 15

When does the strength of ionic bonds increase

Answer 15

As the charge on the ions increase
When the size of the ions decrease

Question 16

How does ionic size change as you go down the group

Answer 16

Increases as there are more electron shells

Question 17

How does ionic size change as you go across a period

Answer 17

Decreases as the proton no. increases, so the force of attraction from the nucleus is greater. Furthermore, this decreases the size of the atom because the electrons are still in the same shell

Question 18

Why can ionic compounds only conduct electricity when they are molten or dissolved in water

Answer 18

Because their ions are free to move and ‘carry charge’

Question 19

Which kinds of solvents are ionic compounds usually soluble and insoluble in

Answer 19

Usually soluble in polar solvents such as water and insoluble in non-polar solvents such as cyclohexene

Question 20

Why are ionic compounds hard

Answer 20

The strength of the bonds between oppositely charged ions is high, therefore a lot of force is required to overcome these bonds

Question 21

Why are ionic compounds brittle

Answer 21

The layers of ions slide over each other and ions of the same charge will repel each other and so break the structure with a clean sharp surface

Question 22

What is the name of the orbital formed when a covalent bond forms

Answer 22

Molecular orbital

Question 23

What is the general rule about atom size and bond strength

Answer 23

The smaller the atom, the stronger the bond

Question 24

What is unique about a dative (co-ordinate) bond

Answer 24

Both bonding electrons come from the same atom in the molecule

Question 25

How do dative bonds behave

Answer 25

Identically to an ordinary covalent bond

Question 26

How is a dative bond represented

Answer 26

By an arrow, pointed away from the atom that contributes both electrons

Question 27

What is the basic shape of a molecule determined by

Answer 27

The number of pairs of electrons around the central atom

Question 28

Why might the basic shape of a molecule be distorted

Answer 28

The presence of lone pairs of electrons as they create repulsion

Question 29

What shape do 2 pairs of electrons form and what is the bond angle

Answer 29

Linear
Bond angle of 180 degrees

Question 30

What shape do 3 pairs of electrons form and what is the bond angle

Answer 30

Trigonal planar
Bond angle of 120 degrees

Question 31

What shape do 4 pairs of electrons form and what is the bond angle

Answer 31

Tetrahedral
Bond angle of 109.5 degrees

Question 32

What shape do 5 pairs of electrons form and what is the bond angle

Answer 32

Trigonal bipyramidal

Bond angle between axial and equatorial atom is 90 degrees

Bond angle between 2 equatorial atoms is 120 degrees

Question 33

What shape do 6 pairs of electrons form and what is the bond angle

Answer 33

Octohedral
Bond angle of 90 degrees

Question 34

By how many degrees does a lone pair reduce the bond angle

Answer 34

2.5 degrees

Question 35

Why are molecular shapes the way they are

Answer 35

The molecule adopts the position that minimises repulsive forces

Question 36

What symbol is used to indicate electronegative charge

Answer 36

Delta

Question 37

What do molecules that have one end of the molecule slightly more negative compared to the other have

Answer 37

Permanent dipole or a dipole moment

Question 38

How can molecules have polar bonds but be a non-polar molecule

Answer 38

If the molecule is symmetrical and the dipoles and pointing towards each other, they can cancel out