C2

Question 1

What is ionic bonding?

Answer 1

The transfer of electrons from a metal to a non-metal
eg. Sodium chloride, Magnesium oxide

Question 2

What is covalent bonding?

Answer 2

The sharing of electrons between two non-metals
eg. NH3, CH4

Question 3

What is metallic bonding?

Answer 3

the bonding within a metal/alloy which involves positive ions and a sea of delocalised electrons

• the delocalised electrons (free to move) are able to conduct heat and electricity

Question 4

Why do electrons become delocalised in metals?

Answer 4

the electron orbitals in metal atoms overlap

Question 5

Explain ionic bonding

Answer 5

• when a metal atom reacts with a non-metal atom, electrons in the outer shell of the metal atom are transferred
• metal atom loses electrons= positive charged ion (cation), with a full outer shell
• non-metal atom gains electrons= negatively charged ion (anion), with a full outer shell
• the oppositely charged ions are held together by strong electrostatic forces of attraction

Question 6

What can be used to represent the electron transfer during the formation of an ionic compound?

Answer 6

A dot and cross diagram

Question 7

What is an ionic compound?

Answer 7

a giant ionic lattice held together by strong electrostatic forces of attraction between oppositely charged ions (which act in all direction in the lattice)

Question 8

Explain covalent bonding

Answer 8

when atoms share pairs of electrons (for a full outer shell) and form strong covalent bonds

Question 9

What are limitations of the simple model of the states of matter?

Answer 9

• in the model forces are not shown
• all particles are represented by spheres which is not the case
• the spheres are solid

Question 10

What are properties of ionic compounds?

Answer 10

• high melting and boiling points due to strong electrostatic forces which requires large amount of energy to overcome
• can conduct electricity when molten or dissolved in water because there are delocalised ions can move and carry a current

Question 11

Describe the structure and properties of simple covalent bonds(small molecules)

Answer 11

• held together by covalent bonds
• low melting and boiling points because there are weak intermolecular forces that are overcome when the substance melts or boils
• usually gases or liquids
• do not conduct electricity(molecules have no overall electric charge)

Question 12

Describe the structure and properties of giant covalent structures

Answer 12

• solids with very high melting points
• all atoms in this structure are linked to other atoms by strong covalent bonds
• high amounts of energy are needed to overcome these bonds= high melting and boiling points
  eg. diamond, silicon dioxide

Question 13

What are alloys?

Answer 13

Alloys are made from two or more different types of metals

Question 14

Why do most metals have high melting and boiling points?

Answer 14

Metals have giant structures of atoms with strong metallic bonding

Question 15

What are polymers?

Answer 15

Polymers are long chains of repeating units; they are very large molecules that are made up of monomers

Question 16

What type of bond joins all the atoms in a polymer?

Answer 16

strong covalent bonds

Question 17

Why are most polymers solid at room temperature?

Answer 17

The intermolecular forces between polymer molecules are relatively strong, so a large amount of energy is needed to break them

Question 18

What are the two types of polymers?

Answer 18

Addition and Condensation

Question 19

Describe the structure of diamond

Answer 19

• each atom forms 4 covalent bonds with other carbon atoms
• giant covalent structure so it is very hard has a high melting point
• does not conduct electricity

Question 20

Describe the structure of graphite

Answer 20

• each carbon atom is covalently bonded to 3 other carbons, forming hexagonal rings(layers). There are no covalent bonds between layers.
• soft(layers can slide) and conducts electricity(due to delocalised electrons)

Question 21

Give a use of graphite

Answer 21

Pencil

Question 22

Describe the structure of graphene and fullerenes

Answer 22

• graphene is a single layer of graphite
• uses of graphene: electronics and composites
• fullerenes are molecules of carbon with hollow shapes
• based on hexagonal rings of carbon atoms
• are hard
• can be used as a lubricant, future(drug delivery)

Question 23

What are nanoparticles?

Answer 23

very small particles of 1-100 nm in size

Question 24

Give an example of a coarse particle

Answer 24

dust

Question 25

Why do nanoparticles make good catalysts?

Answer 25

They have high surface area: volume ratios so smaller quantities are needed to be effective than normal size particles

Question 26

Give uses of nanoparticles

Answer 26

• electronics- small electrical circuits(conduct electricity)
• cosmetics and sun creams
• deodorants
• medicine- drug delivery

Question 27

Give disadvantages of nanoparticles

Answer 27

• may be toxic
• may be able to enter the blood stream and cause harm
• new so very little scientific knowledge