unit one, section one: atomic structure

Question 1

what are protons and neutrons sometimes known as

Answer 1

nucleons as found in the nucleus

Question 2

what are the relative charges and masses of subatomic particles

Answer 2

neutrons : mass = 1 , charge = 0
protons : mass = 1, charge = +1
electrons : mass = 1/1840 , charge = -1

Question 3

what force holds protons and neutrons

Answer 3

strong nuclear force , stronger than electrostatic forces , acts over very short distances

Question 4

what force holds electrons and protons together

Answer 4

electrostatic forces

Question 5

what is the atomic number (proton number)(bottom num)

Answer 5

number of protons or electrons

Question 6

what is the mass number (top number)

Answer 6

number of protons and neutrons

Question 7

define isotope and properties

Answer 7

an atom with same number of proton but different num of neutrons is an isotope

• different isotopes of same element react same as same electron configuration
• mass number may differ due to more neutrons
• physical properties are the same

Question 8

what is the maximum number of electrons in each sub shell

Answer 8

s = 2
p = 6
d = 10
f = 14

Question 9

do you fill 3d or 4s first?

Answer 9

4s as technically lower energy level

Question 10

what do orbital spaces represent

Answer 10

regions of space that electrons are most likely to be in as we can’t know for definite

Question 11

what is aufbau principle

Answer 11

electrons enter the lowest energy orbital available

Question 12

what are the rules for allocating electrons to atomic orbitals

Answer 12

1) atomic orbitals of lower energy are filled first

Question 13

whats Hund’s rule

Answer 13

electrons prefer to occupy orbitals on their own and only pair up when no empty orbitals of the same energy are available (bus)

Question 14

how does the electron configuration change with ions

Answer 14

electrons in the highest energy levels are lost first HOWEVER lost from 4s before 3d except Cu and Cr

Question 15

what is the anomaly with Cu and Cr

Answer 15

Using the Aufbau principle, you would write the following electron configurations
Cr = [Ar] 
4
s
2

3
d
4

Cu = [Ar]
4
s
2

3
d
9
The actual electron configurations are:
Cr = [Ar] 
4
s
1

3
d
5

Cu = [Ar]
4
s
1

3
d
10
To understand why this occurs, it is important to realize that…
1. Completely filled sublevels are more stable than partially filled sublevels.
2. A sublevel which is exactly half filled is more stable than a partially filled sublevel which is not half full.
3. Electrons are lazy and will do whatever places them in the lowest energy state = which is the most stable state

Question 16

where do we get evidence for this atomic structure

Answer 16

ionisation energies

Question 17

what is the definition of 1st ionisation energy

Answer 17

the energy required to remove one electron from each atom in a mole of gaseous atoms producing one mole of 1+ gaseous ions

Question 18

what is second ionisation energy

Answer 18

energy required to remove the second electron (not both)

Question 19

describe and explain three factors the ionisation energy

Answer 19

1) distance from the nucleus (atomic radius)
- further away from the nucleus, less attracted to nucleus , easier to remove (less energy req)
2) nuclear charge (draw from protons)
- as go along group higher nuclear charge, protons attract electrons more, smaller radius, harder to remove (more energy req)
3) shielding
- nucleus is shielded by inner electrons , more shells more shielding , weaker attraction between nucleus and outer e’s (less energy req)

Question 20

what must you specify when talking about attraction

Answer 20

what the attraction is between

Question 21

why would 3p3 have a stronger ionisation energy than 3p4

Answer 21

in 3p4 there is a pair of electrons , leads for small amount of repulsion as electrons are both neg so easier to remove

Question 22

why would ionisation energy decrease as another sub shell is added

Answer 22

slight increase in shielding and further away from nucleus so less energy req

Question 23

what is mass spectroscopy

Answer 23

powerful instrumental technique used to find the relative mass of elements and compounds and identify elements and molecules

Question 24

name the 4 stages of flight of mass spec

Answer 24

1) ionisation
2) acceleration of ions
3) separation 3of charged ions
4) detection

Question 25

explain ionisation and the two methods

Answer 25

sample must be ionised to be detected, must be vaporised to ionised

1) electron impact is used for elements and low Mr compounds
- high energy electrons are fired from electron gun to remove a outer electron forming 1+ ion.
- X(g) -> X+(g) + e-
2) electro spray ionisation is used with high Mr compounds
- sampled dissolved in a volatile ( vaporises easily) solvent eg. water and injected through hypodermic needle as fine spray into vacuum (isolate sample)
- needle is positively charged and high voltage at end
- particles gain a proton and become 1+ ions
- X(g) + H+(g) -> XH+ (g)
- solvent evaporates leaving 1+ ions

Question 26

explain what happens in the acceleration of ions

Answer 26

ions are accelerated using an electric field so that ions have SAME KINETIC ENERGY
- for this to happen the sample MUST be ionised

Question 27

explain what happens in separation of charged ions

Answer 27

ion drift occurs - ions enter the flight tube , ions with different masses have different time of flight
- lighter ions travel faster and take less time to hit the detector

Question 28

what happens in detection

Answer 28

the detector is an negatively charged plate to a) attract particles and b) give an electron to pos ions to produce a current

• mass of ion can be calculated by time of flight
• mass spectrum shows abundance of each mass that hit the detector

Question 29

what do the peaks on a mass spectrum chart show

Answer 29

n of isotopes and abundance

Question 30

what is the horizontal axis on a mass spectrum chart

Answer 30

mass to charge ratio (m/z)

- in electron impact if 2 electrons are accidentally knocked off this must be accounted for

Question 31

what is the n+1 peak accounted for

Answer 31

due to existence of carbon 13 and hydrogen 2 - ignore

Question 32

what is the molecular ion peak

Answer 32

the biggest peak and corresponds to the Mr of the sample

Question 33

what must you remember with diatomic atoms with mass spec

Answer 33

much more likely to have 2 atoms that form ionic mol
look at chlorine examples
- use probability to work out graph

Question 34

MUST GO OVER FINDING AR EXAMPLES WITH FOMS

Answer 34

DO IT

Question 35

suggest what may cause the relative atomic mass of a sample to be different from RAM in periodic table

Answer 35

existence of other isotopes

Question 36

explain Dalton’s and Thomson’s model

Answer 36

Thomson = plum pudding model in 1897
Dalton = beginning 19th century described atoms as solid spheres

Question 37

explain Rutherford’s model

Answer 37

1909 fired alpha particles at gold foil. most past straight through but some deflected, positive centre and cloud of electrons

Question 38

explain Bohr’s model

Answer 38

electrons in fixed orbits and not anything else
each shell has a fixed energy level
when electron moves between shells electromagnetic radiation is admitted or absorbed
radiation fixed frequency

Question 39

what is the general equation for the nth ionisation

Answer 39

X(n-1)(g) -> Xn + e

Question 40

mass spec maths

Answer 40

please refer to question book and flash cards

do it!!!!!!!!

Question 41

explain how ions are detected and relative abundance is measured

Answer 41

• ions hit detector and gain electron

- abundance is proportional to current