Atomic Structure Flashcards
What was Dalton’s model of the atom?
Billiard Ball
- all atoms of the same element have the same mass and are the same
- tiny
- indivisible
What was JJ Thompson’s model of the atom?
Plum Pudding
- discovered the electron
- negatively charged electrons floating in a ‘sea’ of positive charge
What was Rutherford’s model of the atom?
- discovered the nucleus
- holds most of the mass in a tiny centre with positive charge
- lots of empty space
How did Rutherford prove his model?
Gold foil experiment
- shooting alpha particles at some gold foil and seeing how many particles deflect and where they go
What was Bohr’s model of the atom?
- discovered energy shells
- each shell is fixed and has a fixed energy level
- electromagnetic radiation is either absorbed or emitted when an electron moves shell
What was Chadwick’s model of the atom?
- discovered the neutron
- a sub-atomic particle with neutral charge that is in the nucleus
what is the charge on a proton?
+ 1.6 x 10⁻¹⁹
what is the charge on neutron?
0
what is the charge on an electron?
- 1.6 x 10⁻¹⁹
what is the mass (kg) of a proton?
1.67 x 10⁻²⁷
what is the mass (kg) of a neutron?
1.67 x 10⁻²⁷
what is the mass (kg) of an electron?
9.11 x 10⁻³¹
what is the relative masses of p, n and e?
p = +1
n = +1
e = 1/1836
what is the relative charges of p, n and e?
p = +1
n = 0
e = -1
what is an isotope?
atoms of the same element, which therefore have the same number of protons and electrons, but have a different number of neutrons
what is relative atomic mass (Ar)?
the average mass of an atom of an element compared to the 1/12 the mass of a carbon-12 isotope
how to calculate Ar?
(isotope mass x %abundance) / 100
how to calculate Mr?
(mass1 x y) + (mass2 x (100 - y)) / 100
e.g. (203 x y) + (205 x (100 - y)) / 100
y = 30
what is relative molecular mass (Mr)?
the average mass of a molecule relative to one twelfth of the mass of an atom of carbon-12.
how can you measure the mass and abundance of each isotope in an element (Ar) or to find the relative molecular mass of a substance?
Time of Flight (TOF) Mass Spectrometer
what are the 5 phases of mass spectrometry?
- ionisation
- acceleration
- ion drift
- detection
- data analysis
what are the two methods of ionisation (mass spectrometry)?
- electrospray - particles gain a proton
X(g) + H⁺ -> XH⁺(g) - electron bombardment - an electron is knocked off
X(g) -> X⁺(g) + e⁻
which method of ionisation is better for larger particles?
electrospray
which method of ionisation is better for smaller particles?
electron bombardment
how does the acceleration phase of mass spectrometry work?
an electric field accelerates ions so that they all have the same Ke
what happens during the ion drift phase of mass spectrometry work?
ions enter a region with no electric field, which is also a vacuum
- lighter ions travel faster than heavier ions
what happens during the ion detection phase of mass spectrometry work?
- ions reach the detector
- gain electrons from negative plate
- causes a current to flow
- the more ions of the same mass - the larger the current
- current is proportional to abundance
what happens during the data analysis phase of mass spectrometry work?
flight times and size of current are analyised and recorded as a mass spectrum - mass/charge vs relative abundance
Ke = …
Ke = 1/2 m v²
v = d/t
what are the proper names for shells?
principal energy levels
what are principal energy levels split up into?
sub-shells
s, p, d, f
what are sub-shells split up into?
orbitals
how many electrons can each orbital hold?
2
what are s-sub-shells consisting of?
1s orbitals - 2 e
what are p-sub-shells consisting of?
3p orbitals - 6e
what are d-sub-shells consisting of?
5d orbitals - 10e
what are f-sub-shells consisting of?
7f orbitals - 14e
1 sub-level consists of?
1 x s = 2e
2 sub-levels consists of?
1 x s = 2e
3 x p = 6e
8e total
3 sub-levels consists of?
1 x s = 2e
3 x p = 6e
5 x d = 10e
18e total
4 sub-levels consists of?
1 x s = 2e
3 x p = 6e
5 x d = 10e
7 x f = 14e
32e total
what is the order of the orbitals in terms of energy levels?
1s , 2s , 2p , 3s , 3p , 4s , 3d , 4p , 4d , 4f
