Bonding, structure and properties of matter

Question 1

What are ions?

Answer 1

Charged particles

metals lose electrons to become positive ions but non-metals lose electrons to become negative ions

Question 2

What is ionic bonding?

Answer 2

Bonding between a metal and non-metal.

Question 3

Explain ionic bonding

Answer 3

Metal atom loses electrons to form a positively charge ion.
Non-metal gains these electrons to form a negatively charged ion.
These oppositely charged ions are attracted to one another by electrostatic forces.

Question 4

What structure do ionic compounds have?

Answer 4

giant ionic lattice
(regular lattice arrangement with very strong electrostatic forces of attraction between oppositely charged ions in all directions of the lattice)

Question 5

What properties do ionic compounds have?

Answer 5

• high melting and boiling points (due to strong bonds between ions which need lots of energy to overcome)
• when they’re solid, the ions can’t conduct electricity
• when they’re molten or dissolved in water, they can conduct electricity because the ions are free to move and to carry the current

Question 6

What is covalent bonding?

Answer 6

Bonding between non-metals

Question 7

Explain covalent bonding

Answer 7

non-metal atoms share electrons in their outer shells so that each atom has enough covalent bonds to have a full outer shell.

Question 8

What properties do simple covalent molecules have?

Answer 8

• very low melting and boiling points (very weak intermolecular forces that are easily overcome)
• don’t conduct electricity

Question 9

What properties do giant covalent structures have?

Answer 9

• very high melting and boiling points (as lots of energy is required to break the strong covalent bonds)
• generally don’t conduct electricity

Question 10

What is diamond like?

Answer 10

giant covalent structure made up of carbon atoms that each form 4 covalent bonds

• very hard (^^)
• very high melting point (due to covalent bonds)
• doesn’t conduct electricity (no free electrons)

Question 11

What is graphite like?

Answer 11

giant covalent structure made up of carbon atoms that each form 3 covalent bonds, creating sheets of carbon atoms
no covalent bonds between layers, just weak forces. this makes graphite soft and slippery
high melting point (covalent bonds require lots of energy to break)
conducts electricity and thermal energy

Question 12

What is graphene like?

Answer 12

one layer of graphite (just one atom thick!)

• very strong
• light
• conducts electricity and heat

Question 13

What are fullerenes?

Answer 13

molecules of carbon shaped like closed tubes or hollow balls
mainly arranged in hexagons (or pentagons or heptagons)
eg. buckminsterfullerene

Question 14

How can fullerenes be used?

Answer 14

• catalysts (because of large surface area)
• lubricants
• to deliver a drug (cage the drug)

Question 15

What is nanotechnology?

Answer 15

Technology that uses very small particles like nanotubes

Question 16

What is metallic bonding?

Answer 16

bonding between metals

Question 17

Explain metallic bonding

Answer 17

The electrons in the outer shell of the metal atoms are delocalised. There are strong forces of attraction between the positive metal ions and shared electrons.

Question 18

What is the difference between alloys and pure metals?

Answer 18

Pure metals are just one element and are too soft for most jobs so they’re mixed with other elements to form alloys. As the different elements have different sized atoms, the new atoms distort the layers of the metal atoms, making it more difficult for them to slide over eachother. This makes alloys much harder than pure metals.

Question 19

What is the size of the diameter of a coarse particle?

Answer 19

between 2500 nm and 10,000 nm

Question 20

What is the size of the diameter of a fine particle?

Answer 20

between 100 nm and 2500 nm

Question 21

What is the size of the diameter of a nanoparticle?

Answer 21

between 1 nm and 100 nm

Question 22

What can nanoparticles be used for? (And why?)

Answer 22

• to make new catalysts (nanoparticles have a large surface area to volume ratio)
• nanomedicine (nanoparticles are more easily absorbed by the body eg. to deliver drugs)
• tiny electrics circuits (some nanoparticles conduct electricity)
• in cosmetics
• to add antibacterial properties for surgical masks, wound dressings, deodrants, etc. (silver nano particles have antibacterial properties)

Question 23

What are the effects of nanoparticles on the body?

Answer 23

currently unknown
products must be tested to check they are safe
long term impacts on health are unknown which makes some people hesitant to use products containing them so they must be clearly labelled