Bonding, structure, and the properties of matter

Question 1

What happens to the size of intermolecular forces as the size of molecules increase?

Answer 1

The size of intermolecular forces increase (hence higher melting and boiling points for larger molecules)

Question 2

What are the limitations of the following diagrams to represent ionic structures? Dot and Cross Ball and Stick

Answer 2

• Dot and cross: Doesn’t show the structure of the ionic compound, the size or arrangement of ions. • Ball and stick: Suggests gap between ions which aren’t in fact there.

Question 3

Describe the structure and bonding of Graphite.

Answer 3

• Giant covalent structure • Each carbon forms three covalent bonds with other carbon atoms • Forms layers of hexagonal rings • No covalent bonds between layers • One electron from each carbon atom is delocalised

Question 4

What state are most polymers at room temperature? Why?

Answer 4

• Solid • Because they are large molecules, with strong intermolecular forces, hence relatively high melting and boiling points (compared with small molecules).

Question 5

Diamond and graphite are made out of a single element. Name this element.

Answer 5

Carbon

Question 6

Why do small molecules usually have relatively low melting and boiling points?

Answer 6

• They have weak forces between molecules (intermolecular forces) • It is the intermolecular forces that are overcome, not the covalent bonds, when the substance boils.

Question 7

Describe how sodium and chlorine bond to form sodium chloride.

Answer 7

• The sodium atom loses one electron to become a sodium ion • The chlorine atom gains one electron to become a chloride ion • The positive sodium ion is attracted to the negative chloride ion to form sodium chloride.

Question 8

What charge do the ions of elements in the following groups have?: a) Group 1 b) Group 2 c) Group 6 d) Group 7

Answer 8

a) Group 1: + b) Group 2: 2+ c) Group 6: 2- d) Group 7: -

Question 9

What are cylindrical fullerenes called and why are they useful?

Answer 9

• Nanotubes • They have a high length to diameter ratio making them useful for nanotechnology, electronics and materials.

Question 10

Do metals have high or low melting points and boiling points?

Answer 10

High melting and boiling points

Question 11

Describe the properties of Diamond.

Answer 11

• Hard • Very high melting point • Doesn’t conduct electricity

Question 12

Describe the structure and bonding of Diamond.

Answer 12

• Giant Covalent Structure • Each carbon forms four covalent bonds with other carbon atoms

Question 13

What type of bond exists between metals and non-metals in a compound?

Answer 13

Ionic Bond

Question 14

What element are all fullerenes made from?

Answer 14

Carbon

Question 15

What is graphene?

Answer 15

A single layer of graphite

Question 16

Why are metals good conductors of heat and electricity?

Answer 16

They have delocalised electrons that can carry the charge (in terms of conducting electricity) or transfer energy (in terms of conducting heat)

Question 17

What type of bond exists in non-metal elements and compounds?

Answer 17

Covalent Bond

Question 18

In which type of bond are electrons transferred?

Answer 18

Ionic bond

Question 19

What bonds must be overcome in order to melt or boil giant covalent structures?

Answer 19

The strong covalent bonds between the atoms.

Question 20

Describe the structure and bonding in a metal.

Answer 20

• Metallic bonding • Strong metallic bonds • Giant structure of metal atoms in regular pattern • Outer shell electrons are delocalised

Question 21

When atoms gain or lose electrons to become ions, they will have the electron structure of what group of elements?

Answer 21

Noble gases

Question 22

What is the name for the forces that exist between ions in an ionic bond?

Answer 22

Electrostatic forces

Question 23

In which type of bond are electrons shared?

Answer 23

Covalent bond

Question 24

What type of bonding exists in metallic elements and alloys?

Answer 24

Metallic bonding

Question 25

What do the following state symbols represent? a) s b) l c) g d) aq

Answer 25

a) Solid b) Liquid c) Gas d) Aqueous (dissolved in water)

Question 26

What type of bonds exist in large molecules, such as polymers?

Answer 26

Covalent bonds

Question 27

What is the chemical formula of Buckminsterfullerene?

Answer 27

C60

Question 28

What charge do non-metal ions have?

Answer 28

Non-metal ions are negative

Question 29

Can molecules conduct electricity? Give a reason for your answer.

Answer 29

No, because they have no overall electric charge.

Question 30

Describe the structure of fullerenes

Answer 30

Mostly hexagonal rings of carbon (will also have rings with 5 or 7 carbon atoms). Can be spherical or cylindrical in shape.

Question 31

What is the relationship between the forces between particles and a substance’s melting and boiling points?

Answer 31

The stronger the forces between particles, the higher the melting and boiling points (or vice versa)

Question 32

Give three examples of giant covalent structures.

Answer 32

• Diamond • Graphite • Silicon dioxide

Question 33

Name two uses of graphene.

Answer 33

Used in electronics and composites

Question 34

Why do ionic compounds have high melting and boiling points?

Answer 34

Because a lot of energy is needed to break the many strong bonds.

Question 35

Why do molten or aqueous solutions of ionic compounds conduct electricity?

Answer 35

Ions are free to move so charge can flow

Question 36

What charge do metal ions have?

Answer 36

Metal ions are positive

Question 37

Small molecules contain what type of bonds?

Answer 37

Covalent bonds

Question 38

Describe the structure and bonding of an ionic compound.

Answer 38

• Ionic bonding • Giant structure of ions • Lattice structure • Oppositely charged ions held together by electrostatic forces acting in all directions

Question 39

What is the name for the electrons that are free to flow in metallic bonding?

Answer 39

Delocalised electrons