Chemistry

Question 1

what is an isotope?

Answer 1

different atomic forms of the same element, which have the SAME number of protons but a DIFFERENT umber of neutrons

Question 2

properties of ionic compounds?

Answer 2

• high melting and boiling points

- when melted or dissolved they can conduct electricity

Question 3

what is the charge of an ion which has gained an electron?

what is the charge of an ion which has lost an electron?

Answer 3

negative

postitive

Question 4

properties of simple molecular substances?

Answer 4

• low melting and boiling points
• gases or liquids at room temperature
• dont conduct electricity

Question 5

properties if giant covalent bonds?

Answer 5

• very high melting and boiling points

- dont conduct electricity(apart from graphite)

Question 6

properties of a diamond and graphite?

Answer 6

diamond- four covalently bonded carbon atoms. very hard.
graphite- 3 covalently bonded carbon atoms rather than 4. this makes graphite slippery and good conductor of electricity cause it has a de localised electron.

Question 7

properties of metallic structures?

Answer 7

• hard, malleable

- delocalised electron so it can conduct heat and electricity

Question 8

what holds the metallic structure together?

Answer 8

the electrons and the positive ions have a strong electrostatic attraction.

Question 9

why are alloys harder than pure metals?

Answer 9

the different sized atoms means that the layers are distorted therefore do not slide over each other and are therefore harder.

Question 10

what is nitinol and why is it used in medicine?

Answer 10

nitinol is a “smart material” that can remember a shape it used to be. it is used in braces as the mouth warms up the nitinol tries to go back to the ‘remembered shape’ and pulls the teeth with it.

Question 11

how big is nano particle?

Answer 11

contains roughly a few hundred atoms

Question 12

give 3 examples of nanoscience?

Answer 12

1) nanotubes can be used in building materials
2) they can be absorbed by the body better therefore can deliever drugs to the right cells quicker
3) used in sun cream as they do the right job yet dont leave white marks on the skin.

Question 13

what is a thermosetting polymer?

Answer 13

they have crosslinks. these hold the chains together in a solid structure, therefore these will not soften when heated. they are hard, rigid and strong.

Question 14

what is a thermosoftening polymer?

Answer 14

the do not have crosslinks between the chains, they can melt very easily and therefore soften when heated. (remould)

Question 15

what is low density polythene?

Answer 15

made by heating ethene to bout 200 degrees under a HIGH pressure. is flexible and used in bags and bottles

Question 16

what is high density polythene?

Answer 16

made at a lower temperature and LOWER pressure its more rigid and used in drainpipes and water tanks

Question 17

what is the relative atomic mass?

Answer 17

how heavy the different atoms are. (usually the same as the mass number)

Question 18

what is the relative formula mass?

Answer 18

in a compound, is the relative atomic mass of all the atoms ADDED TOGETHER.

Question 19

what is a mole?

Answer 19

the relative formula mass of a substance in grams

Question 20

how do you figure out how many moles?

Answer 20

NUMBER OF MOLES= mass in g(of element or compound) DIVIDED BY the relative formula mass (of element or ompound)