1.1 Atomic structure Flashcards
Bohr model
Consists of protons and neutrons in a nucleus and electrons in shells
JJ Thompson
Plum pudding model
Ernest Rutherford
Nuclear model
Properties of subatomic particles
Relative mass p-1 n-1 e-1/1840
Relative charge p-+1 n-0 e–1
Atomic number
Number of protons
Z
Mass number
Protons and neutrons
A
Cations
Lost electrons
Always paws-ative
Anions
Gained electrons
Negative
Isotopes
Atoms with the same number of protons but different number of neutrons
Why do isotopes of the same elements have the same chemical properties
They have the same electron configuration
Gold sheet experiment
Rutherford fired He2+ ions at a gold sheet
Most particles passed through as mostly empty space, some were deflected
Concluding, atoms are mostly empty space but have a small positive nucleus
What does the Bohr model have
Electron shells
Small positive nucleus
Neutrons in nucleus
Ionisation energy
The amount of energy it takes to remove one mole of electrons from one mole of atoms in a gaseous state
First ionisation of rubidium equation
Rb (g) –> Rb+ (g) + e-
Effect of nucleus charge on IE
More protons, stronger electrostatic attraction, more energy needed to remove outer electron
IE across period will increase as more protons
Effect of distance from nucleus on IE
Shorter distance, stronger electrostatic attraction, more energy required to remove outer electron
IE down group will decrease as more shells
Effect of shielding on IE
more shells, larger distance between outer electron and nucleus, weaker electrostatic attraction, less energy needed to remove outer electron
IE down a group decreases as distance increases as more shells
S orbital shape
Spherical
P orbital shape
Dumbell
Cr - electron config
1s2 2s2 2p6 3s2 3p6 4s1 3d5
one electron moves from the 4s orbital to 3d to make it more stable
Cu - electron config
1s2 2s2 2p6 3s2 3p6 4s1 3d10one electron moves from the 4s orbital to 3d to make it more stable
Boron deviation ionisation energy explanation
The first e- removed from Be is 2s subshell
The first e- removed from B is 2p subshell
2s is lower than 2p
Less energy is required to remove the B electron
Oxygen deviation ionisation energy explanation
The first e- removed from N is 2p subshell unpaired
The first e- removed from O is 2p subshell paired
Due to electron pair repulsion, less energy is required to remove the electron from O
Deviations in period 3
Aluminium and Sulfur
Ionisation energy down a group
IE decreases
Protons and shielding increases
Distance from nucleus increases
Electrostatic attraction gets weaker
Less energy needed
Ionisation energy across a period
IE increases
Same shielding
More electrons
Electrostatic attraction stronger
Atomic radius smaller
What does mass spectrometry measure
Relative abundance
Mass / charge ratio
Steps to mass spectrometry
Ionisation
Acceleration
Ion drift
Detection
Why are sample particles ionised
So they can be accelerated towards the negative plate and generate a current by the detector
How are ions accelerated
Positive ions attracted to negative plate
All ions have the same kinetic energy
How are ions separated in the flight tube
Small m/z ions travel at higher speeds than ions will large m/z
How are ions detected
Ions hit the detector
Ion gains an electron
Generates a current
Size of current is proportional to abundance
Electron impact
Sample vaporised
High energy electrons are fired at sample from an electron gun
One electron is knocked off
X (g) –> X+ (g) + e-
Electospray
Sample dissolved in volatile solvent
Injected through fine, hypodermic needle into a fine mist
Positive particles gain a proton
X (g) + H+ –> XH+ (g)
Ar formula
(Mass x abundance) / total abundance
Kinetic energy formula
KE = 1/2 mv2
Velocity formula
V=d/t
Avogadro constant
6.022 x 10^23 mol
