C3- Structure and Bonding

Question 1

How are particles placed in solids liquids and gases?

Answer 1

1) In a solid are packed closely together and vibrate around fixed positions.
2) The particles in a liquid are also close together.but can slip and slide over eachother in random motions.
3) Particles in gases have lots of space between them and zoom around randomly.

Question 2

How is energy transferred in melting and boiling? What time of reaction is this?

Answer 2

1) In melting and boiling, energy is transferred from the surroundings to the substance.
2) This is known as an endothermic reaction.

Question 3

How is energy transferred in freezing and condensing? What type of reaction is this?

Answer 3

1) In freezing and condensing, energy is transferred from the substance to the surroundings.
2) This is known as an endothermic reaction.

Question 4

What is the simple particle model and why does it have its limitations?

Answer 4

1) The simple particle model assumes that particles are made up of solid spheres with no forces operating between them.
2) The simple particle model has its limitations because the atoms, molecules and ions that make up all substances are not solid spheres with no forces between them.

Question 5

How do elements react with eachother to form compounds?

Answer 5

1) Elements react together to form compounds by gaining or losing electrons or by sharing electrons.

Question 6

What happens when elements in group 1 react with elements in group 7?

Answer 6

1) When elements in group 1 react with elements in group 7, atoms of Group 1 can each lose one electron to gain the stable electronic structure of a noble gas.
2) This electron can be given to an atom from Group 7 which then also achieves the stable electronic structure of a noble gas.

Question 7

How are ionic compounds usually formed?

Answer 7

1) Ionic compounds are usually formed when metals react with non-metals.

Question 8

How are ionic compounds held together?

Answer 8

1) Ionic Compounds are held together by strong forces between their oppositely charged ions. This is called Ionic Bonding.

Question 9

Which groups from the periodic table can from ionic compounds?

Answer 9

1) Elements from Group 1 and 7 can form ionic compounds as well as elements from Group 2 and 6.

Question 10

What is the difference between covalent and ionic bonding?

Answer 10

1) Ionic bonding involves transferring electrons whereas Covalent bonding involves sharing electrons.

Question 11

Explain why Ionic compounds have a high melting point.

Answer 11

1) It takes a lot of energy to break the many strong ionic bonds, operating in all directions. These ionic bonds are the bonds which hold a Giant Ionic Lattice together.

Question 12

Why will ionic compounds conduct electricity when molten or dissolved in water?

Answer 12

1) Because their ions can then become mobile and therefore carry a charge through the liquid .

Question 13

What then happens when you supply enough energy to break the ionic bonds in a Giant Ionic Lattice? Why does this happen.

Answer 13

1) The ions become mobile and can start to move around. This happens because the ionic solid melts to become a liquid.

Question 14

When are covalent bonds formed?

Answer 14

1) Covalent bonds are formed when atoms of non metals share pairs of electrons with eachother.
2) Each shared pair of electrons is a covalent bond.

Question 15

What do most substances containing covalent bonds consist of?
What do some other covalently bonded substances have?

Answer 15

1) Many substances containing covalent bonds contain small molecules (eg H20)
2) Some covalently bonded substances have giant structures known as Giant Covalent Structures.

Question 16

Explain what a Giant Covalent Structure is.

Answer 16

1) A giant covalent structure is where huge numbers of atoms are held by a network of covalent bonds.

Question 17

Explain why Simple Molecular Substances have low melting ad boiling points.

Answer 17

1) The forces between simple molecules are weak meaning that it doesn’t require a lot of energy to break the weak intermolecular forces.

Question 18

Explain why Simple Molecular Substances don’t conduct electricity.

Answer 18

1) Simple Molecular Substances don’t have an overall charge so they cannot carry an electrical charge.

Question 19

What is a Polymer? What are they made up of?

Answer 19

1) A polymer is a substance consisting of very large molecules.
2) Polymers are made up of many small reactive molecules that bond to eachother to form long chains

Question 20

Explain why Graphite is soft and slippery.

Answer 20

1) Graphite contains giant layers of covalently bonded carbon atoms.
2) However, there are no covalent bonds between these layers which means that they can slide over eachother.

Question 21

Explain why Graphite can conduct electricity and thermal energy.

Answer 21

1) Graphite can conduct electricity and thermal energy because of the delocalised electrons that can move along its layers.

Question 22

What is Graphene?

Answer 22

1) Graphene is a single layer of graphite and has properties that make it useful in electronics and composites.

Question 23

What are Fullerenes?

What is the structure of Fullerenes based on?

Answer 23

1) Fullerenes are molecules of carbon atoms with hollow hollow shapes.
2) The structure of Fullerenes is based on hexagonal rings of carbon atoms. They may contain rings with five or seven carbon atoms.

Question 24

What are Carbon Nanotubes?

What do their properties make them useful for?

Answer 24

1) Carbon Nanotubes arre cylindrical fullerenes with very high length to diameter ratios.
2) Their properties make them useful for nanotechnology, electronics and materials.

Question 25

What does nanoscience refer to?
What diameters do Nanoparticles have?
What diameters do Coarse particles have?

Answer 25

1) Nano-science refers to structures that are 1-100nm in size.
2) Nanoparticles have diameters between 1x10^-6 and 2.5x10^-6 m.
3) Coarse Particles have diameters between 1x10^-5 and 2.5x10^-6m

Question 26

What happens as the side of cube decreases by a factor of 10?

Answer 26

1) As the side of cube decreases by a factor of 10 the surface area to volume ratio increases by a factor of 10.

Question 27

Why might Nanoparticles have properties which are different from those for the same materials in bulk?

Answer 27

1) This is because of their high surface area to volume ratio. It may also mean that smaller quantities are needed to be effective than for materials with normal particle sizes.

Question 28

What uses do Nanoparticles have?

Answer 28

1) Nanoparticles have many applications in medicine, in electronics, in cosmetics and sun creams, deodorants and as catalysts.