C1

Question 1

what are the 3 separation techniques

Answer 1

filtration, crystallisation, distillation

Question 2

what is filtration used for

Answer 2

to separate substances that are insoluble in a solvent from those that are soluble in the solvent

Question 3

that is crystallisation used for

Answer 3

to obtain pure salt from a salt solution following filtration

Question 4

what is distillation used for

Answer 4

to evaporate the solvent by heating and boiling a solution. the vapour enters a condenser where it is cooled and condensed into a liquid leaving the dissolved solids in the heated flask

Question 5

what is a mixture

Answer 5

2 or more substances not chemically combined

Question 6

what is chromatography process

Answer 6

when you dab a spot of the solution on a pencil like near the bottom of a sheet of chromatography paper. put the paper in a beaker of solvent and the more soluble the substance in the solvent the further up the paper the ink is carried

Question 7

what is atomic number

Answer 7

number of protons and electrons in an atom of that element

Question 8

what order is the periodic table in

Answer 8

order of atomic number

Question 9

what is mass number

Answer 9

number of protons + neutrons in an element

Question 10

what is an isotope

Answer 10

an atom of the same element but with different number of neutrons

Question 11

what can differ between isotopes

Answer 11

physical properties can differ but chemical properties are always the same

Question 12

what does the group number of an element tell you

Answer 12

the number of electrons in the outer shell as it’s the same as the group number

Question 13

what did john dalton do

Answer 13

arranged the elements in order of atomic weights in 1808

Question 14

what did john newlands do

Answer 14

in 1864 arranged the known elements in order of mass and realised that properties of every 8th element seemed similar

Question 15

what did dmitri mendeleev do

Answer 15

1869- founded basis of modern periodic table but left gaps for undiscovered elements

Question 16

why do elements in the same group react in similar ways

Answer 16

because their atoms have the same number of electrons in the outer shell

Question 17

what are typical properties of metals

Answer 17

high melting and boiling points, ductile, malleable (lose electrons)

Question 18

what are typical properties of non metals?

Answer 18

electrical insulators, brittle (gain electrons)

Question 19

which group are the alkali metals

Answer 19

group 1

Question 20

what is an alloy

Answer 20

a mixture of 2 or more elements (at least 1 being a metal)

Question 21

why are metals malleable

Answer 21

the delocalised electrons allow the lattice to distort. when struck by a hammer the metal atoms can slip past one another without breaking up

Question 22

what are metals ductile

Answer 22

the layers of metal atoms slide over each other easily without the metal breaking

Question 23

as the atoms go down a group they get larger and lose electrons more easily and gain electrons less easily, why?

Answer 23

because the outer electrons are further away from the attractive force of the nucleus because there are more shells

Question 24

what can the period number tell you about an element

Answer 24

the number of shells in its atom

Question 25

what are halogens

Answer 25

group 7 toxic non metals
have coloured vapours
low meeting and boiling points that increase going down the table
poor conductors of heat and electricity

Question 26

what do all halogens exist as when elements

Answer 26

molecules made up of pairs of atoms joined by a covalent bond

Question 27

what does electrostatic attraction depend on

Answer 27

distance between outer electrons and nucleus

number of occupied energy levels

size of positive charge on nucleus

Question 28

what are the physical properties of transition elements

Answer 28

good conductors

hard & strong

high density

high melting point (except mercury)

Question 29

what can rutherford’s alpha scattering experiment tell us about the structure of an atom

Answer 29

because very few particles were repelled back, we can tell that atoms have dense, tiny, positively charged nuclei and because most of the particles went straight through the gold foil, most of the atom is free space