2a

Question 1

whats the mass number?

Answer 1

number of protons and neutrons

Question 2

whats the atomic number?

Answer 2

number of electrons

Question 3

what is a compound?

Answer 3

two or more compounds that are chemically bonded

Question 4

what is an isotope?

Answer 4

a different form of the same element which have the same number of protons but a different number of electrons

Question 5

what is ionic bonding?

Answer 5

where atoms lose or gain electrons to form ions which are strongly bonded to each other

Question 6

what are the properties of ionic compounds?

Answer 6

• high melting/boiling points
• carry an electric current
• dissolve in water

Question 7

what type of ion do the elements in group 1 form?

Answer 7

positive ions

Question 8

what type of ion do the elements in group 7 form?

Answer 8

negative ions

Question 9

what is covalent bonding?

Answer 9

where atoms share electrons with each other so that they both have full outer shells

Question 10

what are the two types of covalent substances?

Answer 10

simple molecular and giant covalent

Question 11

3 examples of simple molecular substances

Answer 11

chlorine, oxygen and water

Question 12

3 examples of giant covalent structures

Answer 12

diamond, graphite and silicon

Question 13

why are alloys harder than pure metals?

Answer 13

because they have different sized atoms, making it more difficult for them to slide over each other

Question 14

what is a ‘smart’ material?

Answer 14

a metel alloy that changes shape and then returns to its original shape when heated

Question 15

what are nanoparticles?

Answer 15

really tiny particles that contain a few hundred atoms

Question 16

what is using nanoparticles known as?

Answer 16

nanoscience

Question 17

what is the difference between thermosoftening and thermosetting plastic?

Answer 17

thermosoftening- individual chains of polymers held together by weak intermolecular forces
thermosetting- strong intermolecular forces between the polymer chains called cross link, they hold the chains firmly together.

Question 18

what is relative atomic mass?

Answer 18

the relative atomic mass (Ar) is the same as the mass number of the element

Question 19

what is the relative formula mass?

Answer 19

all the relative atomic masses added together.

Question 20

what is the relative formula mass of a substance known as?

Answer 20

Moles

Question 21

number of moles=

Answer 21

mass in grams/ relative formula mass

Question 22

what three factors can reduce the percentage yield of a reaction?

Answer 22

• the reaction is revisable, therefore the reactants will never be completely converted
• when you filter a liquid, you remove solid particles, you will lose a bit or liquid or solid
• there many be unexpected reactions which use up the reactants.

Question 23

explain how paper chromatography can be used to analyse the dyes used in a brown sweet

Answer 23

• extract the colour and put with a solvent (water, ethanol, salt)
• put spots of the coloured solution on the pencil baseline on the filter paper
• roll up the sheet and put it in a beaker with the solvent
• the solvent will seep up the paper, taking the dye with it
• different dyes form spots in different spaces

Question 24

how does gas chromatography work?

Answer 24

gas chromatography can separate out a mixture of compounds and help to identify the substances present.