elements of life

Question 1

what is the relative mass and charge of a proton?

Answer 1

relative mass= 1
relative charge= +1

Question 2

what is the relative mass and charge of a electron?

Answer 2

relative mass= 0.0005
relative charge= -1

Question 3

what is the relative mass and charge of a neutron?

Answer 3

relative mass= 1
relative charge= 0

Question 4

what does the mass number tell you?

Answer 4

total number of protons and neutrons in the nucleus

Question 5

what does the atomic number tell you?

Answer 5

number of protons

Question 6

what are isotopes?

Answer 6

• atoms of the same element with different mass numbers
• same number of protons, different number of neutrons

Question 7

what is the history of the atom in order?

Answer 7

• DALTON
• JJ THOMPSON
• RUTHERFORD
• BOHR
• CHADWICK

Question 8

what was dalton’s theory of the atom?

Answer 8

invisible spheres

Question 9

what was JJ Thomson’s 1897 theory of the atom?

Answer 9

• discovered atoms weren’t solid
• discovered electrons
• PLUM PUDDING MODEL = ball of positive matter with negative electrons differed evenly throughout

Question 10

what was Rutherford’s 1909 discovery of the atom?

Answer 10

• GOLD FOIL EXPERIMENT
  = fired alpha particles (positively charged) at a thin sheet of gold foil
• most alpha particles passed through, showing most atom is empty space
• some alpha particles deflected back, showing, small dense nucleus
• some alpha particles deflected at an angle, showing nucleus is positive

Question 11

what was Bohr’s 1932 model of the atom?

Answer 11

• electrons exist in fixed shells

Question 12

what is Ar / relative atomic mass?

Answer 12

a weighted average taking into account the abundance of all isotopes

Question 13

what is mass spectroscopy?

Answer 13

mass spectroscopy is a technique that can tell is the % abundance of isotopes of elements, which allows us to calculate Ar

Question 14

what are the steps of mass spectroscopy?

Answer 14

1) sample is vaporised (turned into gas)
2) IONISATION- the gas particles are bombarded with high energy electrons to produce a cation
3) ACCELERATION- the positive ions are accelerated by an electric field
4) DETECTION- time taken for positive ions to reach the detector is measured.
light, highly charged ions reach the detector 1st, heavier ions take longer

Question 15

how do you calculate Ar?

Answer 15

(relative isotopic mass x relative atomic abundance) / 100

Question 16

what is Avogadro’s constant?

Answer 16

6.022*23 × 10

Question 17

what are the arrangements for n= m/mr

Answer 17

m= nxmr
mr= m/n

Question 18

what is 1dm3 converted to cm3

Answer 18

1000cm3

Question 19

what is empirical formula?

Answer 19

the simplest ratio of atoms

Question 20

why is the actual yield normally less than the theoretical yield?

Answer 20

• not all ‘starting’ chemicals fully react
• some chemicals are lost

Question 21

what are titrations used for?

Answer 21

to find out the CONCENTRATIONS of acid or alkali solutions
- allow you to find out exactly how much acid is needed to neutralise a quantity of alkali

Question 22

what are the steps of a titration?

Answer 22

1) Measure out some alkali using a pipettes and put into a flask, along with drops of indicator
2) Fill a burette with acid
3) Do a rough titration, for an idea of where the end point is. To do this take an initial reading to see how much acid is in the burette. Then add yeast acid to alkali, whilst swirling the flask. Stop when there is a colour change (end point) Record final reading
4) For an accurate titration, add the acid dropwise near the endpoint.
5) Work out the amount of acid used to neutralise the alkali.
6) Repeat and work out mean of concordant results

Question 23

how to get an accurate titration?

Answer 23

• use a white tile
• drop wise towards endpoint

Question 24

what is the order of sub shells?

Answer 24

s
p
d
f