Bonding and Structure

Question 1

Define ionic bond

Answer 1

A strong electrostatic force of attraction between oppositely charged ions

Question 2

Define giant ionic lattices

Answer 2

A regular repeating pattern of oppositely charged ions

Question 3

What is the mpt and bpt of ionic compounds, state why

Answer 3

Mpt and bpt are very high because a lot of energy is needed to overcome the strong electrostatic force of attraction between oppositely charged ions

Question 4

Can ionic compounds conduct electricity when they are a solid , state why

Answer 4

Ionic compounds cannot conduct electricity when solid because the ions are not free to move, they are fixed in position in the lattice

Question 5

Can ionic compounds conduct electricity when they are molten or in solution, state why

Answer 5

Ionic compounds do conduct electricity when molten or in solution because the ions can move as the lattice has broken down

Question 6

Are ionic compounds soluble

Answer 6

Yes, because water is polar. Water molecules attract the oppositely charged ions causing the lattice to break down

Question 7

Define covalent bond

Answer 7

The strong electrostatic force of attraction between shared pair of electrons and the nuclei of the bonded atoms

Question 8

Define dative covalent bond

Answer 8

Are covalent bonds which are formed when both electrons are donated by only one of the atoms in the bond

Question 9

What do we need to consider when determining the shape of a molecule

Answer 9

• The number and type of electron pairs around the central atom
• Electron pairs repel each other, as far away as possible
• Lone pairs repel more then bonded pairs

Question 10

What is the shape and bond angle of a molecule with two bonded pairs and 0 lone pairs

Answer 10

Shape = Linear
Bond angle = 180

Question 11

What is the shape and bond angle of a molecule with 3 bonded pairs and 0 lone pairs

Answer 11

Shape = Trigonal planar
Bond angle = 120

Question 12

What is the shape and bond angle of a molecule with 4 bonded pairs and 0 lone pairs

Answer 12

Shape = Tetrahedal
Bond angle = 109.5

Question 13

What is the shape and bond angle of a molecule with 3 bonded pairs and 1 lone pair

Answer 13

Shape = Pyramidal
Bond angle = 107

Question 14

What is the shape and bond angle of a molecule with 2 bonded pairs and 2 lone pairs

Answer 14

Shape = Non-linear
Bond angle = 104.5

Question 15

Define electronegativity

Answer 15

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

Question 16

What elements have a higher electronegativity

Answer 16

• Nitrogen
• Oxygen
• Fluorine
• Chlorine
• Bromine

Question 17

Define non-polar

Answer 17

The electrons are shared equally between the 2 atoms because the atoms have the same( or very similar) electronegativity

Question 18

Define polar

Answer 18

The electrons are shared unequally because one atom has a greater electronegegativity then the other one

Question 19

Define induced dipole dipole intermolecular forces

Answer 19

The weakest inteolecular force of attraction occurring between all molecules and non-polar molecules

Question 20

Define permanent dipole dipole

Answer 20

Slightly stronger intermolecular force of attraction between polar molecules

Question 21

Define hydrogen bonding

Answer 21

Strongest intermolecular force of attraction occurring between hydrogen bonded to F or O or N and a lone pair of electrons

Question 22

Describe how induced dipole dipole forces are made

Answer 22

. At any moment in time the electrons in an atom/ molecule are unevenly distributed
. This creates a temporary ( instantaneous) dipole
. This induces an induce dipole in the neighbouring molecule/ atom
. The two dipoles attracted each other- This is the weakest force of attraction

Question 23

Describe how permanent dipole dipole are made

Answer 23

. These are the attraction between the delta positive and delta negative ends of two polar bonds
. These attractions exist when molecules are polar- when one arom has a higher electronegativity then the other one

Question 24

Describe how hydrogen bonds are made

Answer 24

. Hydrogen bonding occurs when a hydrogen atom is directly bonded to fluorine, oxygen or nitrogen only
. There must be a lone pair of electrons

Question 25

What are the anomalous properties of water

Answer 25

1) water has a relatively high mpt and bpt. This is because when water melts/boils the hydrogen bonds are broken. Hydrogen bonds are the strongest intermolecular forces of attraction and so require a lot of energy to overcome them, hence a higher then expected mpt/bpt
2) When water forms ice it takes the form of a open lattice structure- this results in ice being less dense then water. This is because the hydrogen bonds hold the water molecules further apart in an open lattice structure in ice. This means that the density of ice is less then the density of liquid water

Question 26

Define a simple molecular lattice

Answer 26

A 3D structure of molecules held together by weak intermolecular forces

Question 27

What are the physical properties of simple molecular lattices

Answer 27

. Low mpt/bpt because little energy is needed to break the weak intermolecular forces
. Electrical conductivity- non-conductors because the electrons are localised in bonds and not mobile
. Soluble in non-polar solvents as induced dipole dipole forces will form between the structures and the sovent. Insoluble in polar water

Question 28

Define giant covalent lattices

Answer 28

Is a 3D structure of atoms, all bonded together by strong covalent bonds

Question 29

Properties of giant covalent structure

Answer 29

. High mpt because all atoms are held together by strong covalent bonds which require a lot of energy to break
. Non- conductors of electricity because all electrons are localised in bonds
. Graphite conducts electricity because each carbon has 1 electron which is delocalised and can move to carry a charge
. Insoluble in all solvents because each atom is bonded to every other atom by strong covalent bonds. Atoms cannot interact with solvent molecules

Question 30

Define metallic bonding

Answer 30

Strong electrostatic attraction between the delocalised sea of electrons and the positive ions

Question 31

Compare group 3 and group 1 metals

Answer 31

Group 3 metals will have more delocalised electrons in the sea then group 1

Question 32

properties metals

Answer 32

. Conductivity- metals conduct electricity and heat because the delocalised electrons are free to move
. Mpt/ Bpt- high mpt/ bpt because alot of energy is required to overcome the strong electrostatic forces of attraction between the sea of delocalised electrons and the positive ions

Question 33

Compare the properties of group 3 and group 1 metals

Answer 33

. Conductivity- group 3 metals will have a higher conductivity because there are more valence electrons so more electrons can move in the delocalised sea which can move
. Mpt/Bpt- group 3 metals will have a higher mpt/bpt because there is a stronger attraction between the smaller and more highly charged cations and the delocalised sea of electrons