EL

Question 1

What is nuclear fusion

Answer 1

the coming together of 2 nuclei to form a heavier element. Requires a large amount of energy to overcome repulsive forces. Common in the sun and larger stars.

Question 2

ionic compounds definition

Answer 2

oppositely charged ions held together by electrostatic attractions

Question 3

formula for these ions:
1. hydroxide ion
2. nitrate ion
3. ammonium ion
4. sulfate ion
5. carbonate ion

Answer 3

1. OH-
2. NO3-
3. NH4+
4. SO4 (2-)
5. CO3 (2-)

Question 4

why do most ionic compounds dissolve in water

Answer 4

because water molecules are polar, so they can attract the positive and negative ions and break up the structure.

Question 5

definition of a polar molecule

Answer 5

uneven distribution in electron density due to the differences in electronegativity between atoms in a covalent bond

Question 6

properties of an ionic compound

Answer 6

. conduct electricity when molten/ dissolved in solution as ions are free to move around
. high melting points due to strong electrostatic forces between oppositely charged ions

Question 7

covalent bonding

Answer 7

shared outer electrons to obtain full outer shell. there are electrostatic forces of attraction between the shared electrons and positive nucleus.

Question 8

dative covalent / coordinate bond

Answer 8

where one atom donates 2 electrons to an atom / ion to form a bond.

Question 9

examples of giant covalent structures

Answer 9

diamond, graphite, silicon dioxide

Question 10

why are graphite and diamond insoluble

Answer 10

because they have very strong covalent bonds that are hard to break.

Question 11

why can graphite conduct electricity but diamond can’t

Answer 11

graphite: carbon is bonded 3 times, the 4th electron is part of the delocalised structure - this delocalised structure means free electrons are able to carry a charge

diamond: carbon is bonded 4 times, so there are no free electrons that are able to carry a charge

Question 12

describe a metallic structure

Answer 12

positive metal ions are held together rigidly. the metal ions donate an electron to the sea of delocalised electrons. there is an electrostatic force of attraction between positive metal ions and the negative delocalised electrons

Question 13

why are metals good thermal conductors

Answer 13

because the delocalised electrons can transfer kinetic energy

Question 14

why are metals good electrical conductors

Answer 14

because the delocalised electrons can carry a charge and are mobile.

Question 15

why do metals have high melting points

Answer 15

due to the strong electrostatic attractions between the delocalised electrons and the positive ions

Question 16

generally for every lone pair, how many degrees do you reduce the bond angle by?

Answer 16

2.5

Question 17

2 bond pairs no lone pairs?
3 bond pairs no lone pairs?
4 bond pairs no lone pairs?

Answer 17

. linear = 180 deg.
. pyramidal = 120 deg.
. tetrahedral = 109.5 deg.

Question 18

what happens when an electron absorbs energy

Answer 18

gets excited to a higher energy level. eventually the electron will lose energy and move back down.

Question 19

emission spectrum

Answer 19

black background, coloured lines. shows frequency of light given out when electron moves down energy levels

Question 20

absorption spectrum

Answer 20

coloured background, black lines. electron absorbs the frequency of energy that is equal to the energy gap between shells

Question 21

equation for energy, frequency and wavelength

Answer 21

E = hv
E = energy
h = plancks constant
v = frequency

Question 22

test for ions (using flame test)

Answer 22

1) dip nichrome wire in conc. HCl
2) dip wire into solution
3) present wire to bunsen and observe colour changes

Question 23

what colours?
.Li +
.Na+
.K+
.Ca2+
.Ba2+
.Cu2+

Answer 23

. crimson
.yellow-orange
.lilac
.red
.green
.green-blue

Question 24

isotopes

Answer 24

elements that have the same number of protons but different number of neutrons

Question 25

relative atomic mass

Answer 25

weighted mean mass of an element compared to 1/12th of an atom of carbon-12

Question 26

how do you calculate percentage yield

Answer 26

( actual / theoretical )x 100

Question 27

how do you make a standard solution

Answer 27

1. weigh the solid (make sure you use a plastic / glass weighing boat
2. transfer solid to beaker using deionised water to maintain yield
3. dissolve solid fully with deionised water
4. transfer solution to volumetric flask
5. use more deionised water to fill solution to the graduation line
6. mix solution by shaking (ensure there is a lid)

Question 28

phenolphtalein what colour do acid and alkali turn?
methyl orange what colour do acid and alkali turn?

Answer 28

1. acid - colourless | akali - pink
2. acid - yellow | alkali - red

Question 29

ionisation energy

Answer 29

the minimum amount of energy required to remove one mole of electrons from one mole of atoms in the gaseous state

Question 30

factors affecting ionisation energy

Answer 30

.shielding - the more electron shells there are between outermost electrons and nucleus the easier it is to remove the electrons
.nuclear charge - the bigger the nuclear charge, the greater attraction there is between the nucleus and outermost electrons, means more energy is required to remove electrons
.atomic size - the larger the atom, the weaker the attraction is between the nucleus and outermost electrons - it is easier to remove electrons

Question 31

test for sulfates

Answer 31

add hcl to solution to remove any carbonates
then add barium chloride, a white precipitate should form

Question 32

test for ammonium compounds

Answer 32

add sodium hydroxide to solution. ammonia gas should be produced. then present damp red litmus paper in the test tube. should turn blue

Question 33

test for halides using silver nitrate

Answer 33

testing for chloride, bromide, iodide ions involves adding nitric acid and then silver nitrate solution.
. iodide = yellow precipitate forms
. chloride = white precipitate forms
. bromide = cream precipitate forms