Structure and bonding

Question 1

Isotopes

Answer 1

Different atomic forms of the same element, which have the same number of protons, but different number of neutrons

Question 2

Describe the physical and the chemical properties of isotopes of the same element

Answer 2

Same chemical properties

Different physical properties

Question 3

Calculate the RAM of Cl. If there is 75% of Cl35 and 25% of Cl37

Answer 3

(3575+3725)/100=35.5

Question 4

RAM

Answer 4

Relative atomic mass. Relative to 1/12 of Carbon 12

Question 5

List 3 types of bonding

Answer 5

1) Ionic 2) Covalent 3) Metallic

Question 6

Ionic bonding

Answer 6

Is the transfer of electrons between metals and non-metals

Question 7

What happens to metal atoms when they form an ionic bond?

Answer 7

They lose electrons to form positive ions (cations)

Question 8

What happens to non-metal atoms when they form an ionic bond?

Answer 8

They gain electrons to form negative ions (anions)

Question 9

Describe the forces of attraction in an ionic compound

Answer 9

Strong electrostatic attraction between the positive and negative ions

Question 10

Give an example of a giant crystal structure (2)

Answer 10

1) Sodium chloride 2) Magnesium oxide

Question 11

Describe the arrangement of of ions in a giant structure

Answer 11

The alternate positive and negative ions in an ionic solid are arranged in an orderly way in a giant ionic lattice structure

Question 12

Describe properties of ionic compounds (6)

Answer 12

1) Strong bonding forces make the structure hard. They are not malleable, but brittle
2) Have a high melting and boiling points
3) The greater the charges of the ions the stronger the forces of attraction
4) Many soluble in water. NOT ALL
5) Solid crystals do not conduct electricity
6) Ionic compound melted or dissolved in water will conduct electricity

Question 13

Why solid ionic crystals don’t conduct electricity?

Answer 13

Particles are held in place, therefore no movement of charge

Question 14

Give an example of 2 ionic compounds with different melting points and different charges of ions

Answer 14

1) Mg +2 O -2 (2852C) 2) Na+Cl- (801C)

Question 15

Covalent bonding

Answer 15

Share of electrons between non-metals ONLY

Question 16

What is Cl2

Answer 16

A molecule with no overall charge

Question 17

Describe the attraction forces between molecules

Answer 17

Weak forces of attraction

Question 18

Describe the attraction forces of a covalent bonding

Answer 18

Very strong

Question 19

Describe and explain Melting point of a covalent compound

Answer 19

Low, forces of attraction between individual molecules are weak

Question 20

Describe and explain Physical state at rtp of a covalent molecule

Answer 20

Gasses or liquids with low boiling points or solids with low melting point, weak forces of attraction between the molecules

Question 21

Describe and explain Electrical conductivity of a covalent molecule

Answer 21

Do not conduct electricity, the molecules have no overall charge

Question 22

Describe and explain solubility in water of a covalent molecule

Answer 22

Most are insoluble in water, strong forces of attraction within the molecule

Question 23

Describe physical and chemical properties of diamond (6)

Answer 23

1) Each carbon atom has 4 covalent bonds with its neighbours
2) The atoms are arranged in a giant covalent structure
3) Very high melting point 3500
4) Very hard
5) Not soluble in water
6) Doesn’t conduct electricity

Question 24

Describe physical and chemical properties of graphite(6)

Answer 24

1) Has a layered structure
2) Each carbon atoms forms 3 covalent bonds, which leaves the fourth electron in the bonding level delocalised over the whole of the sheet
3) Delocalised electrons are free to move, therefore conduct electricity
4) Soft
5) Very high melting point 3500
6) Insoluble in water

Question 25

Covalent substances can either be...(2)

Answer 25

1) Giant covalent structure 2) Simple molecular structure

Question 26

Giant covalent structures

Answer 26

Huge 3D networks of atoms with high melting and boiling points

Question 27

Properties of metals(7)

Answer 27

1) Conduct electricity 2) Conduct heat 3) Most metals are hard 4) High melting and boiling points 5) Typically have silvery surface 6) Very malleable 7) Have a high density

Question 28

Metallic bonding

Answer 28

Array of positive ions in a sea of electrons

Question 29

Describe forces of attraction in a metallic bonding

Answer 29

Strong electrical forces of attraction between free and mobile electrons and the 'immobile' positive metal ions

Question 30

Factors affecting the rate of reaction (5)

Answer 30

1) Concentration 2) Catalyst 3) Surface area 4) Temperature 5) Pressure (for gasses)

Question 31

Rate of reaction

Answer 31

Number of successful collisions per second

Question 32

Why concentration results in increase of reactions?

Answer 32

More particles available for collision

Question 33

Why surface area results in increase of reactions?

Answer 33

More particles are exposed to the surface so there are more successful collisions

Question 34

How do catalysts work?

Answer 34

They provide an alternative pathway for reactions, so they occur at lower activation energy. DO NOT REACT THEMSELVES