Atomic Structure

Question 1

what are isotopes?

Answer 1

atoms of the same element with the same number of protons but different number of neutrons

Question 2

what is the atomic number?

Answer 2

(proton number)
number of protons in the nucleus
identifies the element

Question 3

what is the mass number?

Answer 3

total number of protons and neutrons in the nucleus

Question 4

what does the relative charge/mass table look like?

Answer 4

proton 1 +1
neutron 1 0
electron almost 0 -1

Question 5

where is the mass concentrated in an atom?

Answer 5

the nucleus

Question 6

what makes up most of the volume in an atom?

Answer 6

orbitals

Question 7

define relative atomic mass

Answer 7

average mass of an atom of an element on a scale where carbon-12 is 12

Question 8

define relative isotopic mass

Answer 8

mass of an isotope of an element on a scale where carbon-12 is 12

Question 9

explain the difference between relative molecular mass and relative formula mass

Answer 9

relative formula mass is used for ionic or giant covalent compounds

to find, just add up all relative atomic masses for the atoms in the formula

Question 10

describe electrospray ionisation

Answer 10

1. ionisation
   sample is dissolved and pushed through high pressure needle gaining H+ ion and turned into gas
2. acceleration
   positive ions accelerated by electric field so all have same kinetic energy

3.ion drift
no electric field so lighter ions will drift through faster

4. detection
   lighter ions drift faster so will reach detector in less time
   negatively charged plate detects positive ions creating a current

Question 11

electron impact ionisation

Answer 11

1. ionisation
   sample is vaporised and electron gun fires high energy electrons to knock off one electron so they become +1 ions
2. acceleration
3. ion drift
4. detection

Question 12

how do you calculate relative atomic mass from a mass spectrum?

Answer 12

times the abundance by the mass
add up each answer to the first part
divide by the overall abundance

Question 13

how does a mass spectrum determine relative molecular mass?

Answer 13

positive ions produce a peak in spectrum with a mass/charge ratio equal to relative molecular mass

Question 14

write down the sub shells up to 4p

Answer 14

1s 2s 2p 3s 3p 4s 3d 4p

Question 15

how many electrons does each sub shell hold?

Answer 15

s=2
p=6
d=10

Question 16

why do chromium and copper fill up their shells in a different way?

Answer 16

they donate one of their 4s electrons to the 3d sub shell to make it more stable

Cr = 1s2 2s2 2p6 3s2 3p6 4s1 3d5

Cu= 1s2 2s2 2p6 3s2 3p6 4s1 3d10

Question 17

which groups in the periodic table gain electrons to form negative ions?

Answer 17

groups 5,6 and 7ncan gain 1,2 or 3 electrons

Question 18

define first ionisation energy and give an equation as an example

Answer 18

energy needed to remove 1 electron from an atom in 1 mole in a gaseous state to form a +1 ion

O(g) > O+(g) + e-

Question 19

describe the three main factors affecting ionisation energies

Answer 19

1. Nuclear Charge
   the more protons, the more positively charged the nucleus is, the stronger the attraction is between electrons and nucleus
2. distance from nucleus
   electrons close to the nucleus have a stronger attraction then those further away

3.sheilding
the further away the electron the less attraction, the lessening of pull is called shielding

Question 20

explain the relationship between ionisation energy and FoA

Answer 20

a high ionisation energy means a high FoA between electron and nucleus so more energy is required to remove the electron

Question 21

describe the ionisation energy trend in group 2

Answer 21

it decreases as you go down the group

• shielding
• electrons further away less FoA

Question 22

describe the ionisation energy trend across a period

Answer 22

ionisation energy increases
-number of protons increase
-nuclear attraction
x
1st drop is moving sub shell
3p higher energy than 3s so further away from nucleus x

2nd drop is electron repulsion x
easier to remove x
x
x
x
x
x

Question 23

is it easier to remove a lone electron in an orbital or one in a pair?

Answer 23

it is easier to remove an electron from a shared orbital due to electron repulsion