Topic 2 – Bonding, Structure, and The Properties of Matter

Question 1

What is a metallic bond?

Answer 1

A metallic bond is the electrostatic force of attraction between delocalised outer shell electrons and metal ions.

Question 2

Structure of metals

Answer 2

Giant metallic lattice

Question 3

Why do metals have high melting points and boiling points?

Answer 3

Giant lattice structure of many strong metallic bonds require lots of heat energy to break

Question 4

Why are metals malleable and ductile?

Answer 4

Metal’s layers of ions can slide over each other, but are still held together by the delocalised electrons

Question 5

Why are metals good conductors of thermal and electrical energy?

Answer 5

Delocalised outer shell electrons allow heat to flow through the whole structure.

Question 6

What is an alloy?

Answer 6

An alloy is a mixture of a metal element and other elements

Question 7

Why are metal alloys harder than pure metals?

Answer 7

The layers have been distorted and cannot slide over each other

Question 8

Which elements make bronze?

Answer 8

Copper, tin

Question 9

Which elements make brass?

Answer 9

Copper, zinc

Question 10

Which elements make soldier wire?

Answer 10

Lead, sulfur

Question 11

Which elements make duralumin?

Answer 11

Aluminium, copper

Question 12

Which elements make stainless steel?

Answer 12

Iron, carbon, chromium & other elements

Question 13

What is ionic bonding?

Answer 13

lonic bonding is the electrostatic attraction between positive and negative ions. It is a relatively strong attraction.

Question 14

How are ionic compounds held together?

Answer 14

• They are held together in a giant lattice.
• It’s a regular structure that extends in all directions in a substance.
• Electrostatic attraction between positive and negative ions holds the structure together.

Question 15

State properties of ionic substances

Answer 15

• High melting and boiling point (strong electrostatic forces between oppositely charged ions)
• Do not conduct electricity when solid (ions in fixed positions).
• Conduct when molten or dissolved in water - ions are free to move.

Question 16

Give 5 examples of positive ions and 5 examples of negative ions (give names of negative anions).

Answer 16

E.g. Positive: Na, Mg?+, Al3+, Ca?+, Rb
E.g. Negative: CI, Br, SO 2-, NO; ; OH- (chloride, bromide, sulfate, nitrate, hydroxide).

Question 17

What is important when working out a formula of an ionic compound?

Answer 17

lonic compounds are electrically neutral, i.e. positive and negative charges balance each other.

Question 18

How are ionic compounds formed? Explain in terms of MgO case.

Answer 18

Reaction of a metal with a non-metal. Electron transfer occurs - metal gives away its outer shell electrons to non-metal. Mg is in Group II, so has 2 available outer shell electrons. O is in Group VI, so can accept 2 electrons to get a full outer shell configuration.
Mg becomes Mg?+ and O becomes 0?- (oxide).

Question 19

What is a covalent bond?

Answer 19

Covalent bond is a shaired pair of electrons between two atoms.

Question 20

Describe the structure and properties of simple molecular covalent substances

Answer 20

• Do not conduct electricity (no ions)
• Small molecules
• Weak intermolecular forces, therefore:
• Low melting and boiling points

Question 21

How do intermolecular forces change as the mass/size of the molecule increases?

Answer 21

They increase. That causes melting/boiling points to increase as well (more energy needed to overcome these forces).

Question 22

What are polymers?

Answer 22

Polymers are very large molecules (>100s, 1000s of atoms) with atoms linked by covalent bonds.

Question 23

What are thermosoftening polymers?

Answer 23

Thermosoftening polymers - special type of polymers; they melt/soften when heated. There are no bonds between polymer chains. Strong intermolecular forces ensure that the structure is solid at room temperature. These forces are overcome with heating - polymer melts.

Question 24

What are giant covalent substances? Give examples

Answer 24

• Solids, atoms covalently bonded together in a giant lattice.
• High melting/boiling points - strong covalent bonds.
• Mostly don’t conduct electricity (no delocalised electrons)
• Diamond, graphite, silicon dioxide.

Question 25

Describe and explain the properties of diamond

Answer 25

• four, strong covalent bonds for each carbon atom
• very hard (Strong bonds)
• very high melting point (strong bonds)
• does not conduct (no delocalised electrons)

Question 26

Describe and explain the properties of fullerenes

Answer 26

• hollow shaped molecules
• based on hexagonal rings but may have
  5/7-carbon rings
• C, so has spherical shape, simple molecular structure (Buckminsterfullerene)

Question 27

Describe and explain the properties of graphite

Answer 27

• three covalent bonds for each carbon atom
• layers of hexagonal rings
- high melting point
- layers free to slide as weak intermolecular forces between layers; soft, can be used as a lubricant
- conduct thermal and electricity due to one delocalised electron per each carbon atom

Question 28

Describe and explain the properties of nanotubes

Answer 28

• Cylindrical fullerene with high length to diameter ratio
• High tensile strength (strong bonds)
• Conductivity (deloc. electrons)

Question 29

Describe and explain the properties of graphene

Answer 29

• A single layer of graphite

Question 30

Describe properties of metals

Answer 30

High melting/boiling points (strong forces of attraction)
Good conductors of heat and electricity (delocalised electrons)
- Malleable, soft (layers of atoms can slide over each other whilst maintaining the attraction forces)

Question 31

What are the limitations of the simple model?

Answer 31

Limitations of the simple model include that there are no forces between the spheres, and that atoms, molecules and ions are not solid spheres.

Question 32

What does the amount of energy needed to change state from solid to liquid or liquid to gas depend on?

Answer 32

The strength of the forces between the particles of the substance. The nature of the particles involved depends on the type of bonding and the structure of the substance. The stronger the forces between the particles the higher the melting point and boiling point of the substance

Question 33

A pure substance will melt or boil at…?

Answer 33

A fixed temperature.
A mixture will melt over a range of temperatures.

Question 34

What are the three states of matter?

Answer 34

Solid, liquid and gas

Question 35

What is nanoscience?

Answer 35

Science that studies particles that are 1 - 100nm in size

Question 36

State the uses of nanoparticles

Answer 36

• Medicine (drug delivery systems)
• Electronics
• Deodorants
• Sun creams (better skin coverage and more effective protection against cell damage)

Question 37

What are fine and coarse particles?

Answer 37

• Fine particles (soot), 100-2500 nm diameter
• Coarse particles (dust), 2500-105 nm diameter

Question 38

Why do nanoparticles have properties different from those for the same materials in bulk?

Answer 38

High surface area to volume ratio

Question 39

Why are silver nanoparticles used in socks?

Answer 39

Silver nanoparticles have longer-lasting antibacterial properties than bigger particles of silver. That’s why they can be used in socks, to kill bacteria and prevent bad smells.