atomic structure ionisation energies. ionisation energy the first ionisation energy of an element is...
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Atomic Structure
Ionisation Energies
Ionisation Energy
The first ionisation energy of an element is the energy required to remove completely one mole of electrons from one mole of gaseous atoms to form one mole of gaseous ions with a single positive charge.
Na (g) Na+ (g) + e-
Ionisation Energy
The second ionisation energy of an element is the energy required to completely remove one mole of electrons from one mole of gaseous singly charged ions to form one mole of gaseous ions with two positive charges.
Mg+ (g) Mg2+ (g) + e-
Factors Affecting Ionisation Energy
Ionisation energy is a measure of the energy needed to pull a particular electron away from the attraction of the nucleus.
A high value of ionisation energy shows a high attraction between the electron and the nucleus.
Factors Affecting Ionisation Energy
Li
First ionisation
energy
(kJ/mol)
520 419
Ionisation energy decreases when the atom becomes larger because the electrostatic attraction between electrons and protons depends on the distance between the two
the larger the distance the weaker the attraction.
K
Factors Affecting Ionisation Energy
First ionisation
energy
(kJ/mol)
738 590
As the atom gets larger it will also have more energy levels that are full of electrons reduce the electrostatic attraction between protons and electrons. This is called ELECTRON SHIELDING. Hence the ionisation energy will decrease
Mg Ca
Factors Affecting Ionisation Energy
ionisation energy
(kJ/mol)
Ionisation energy increases as the charge on the nucleus increases because the electrostatic attraction between the electrons and protons increases.
10p
2081 7737
12p
Successive ionisation energies
0 1 2 3 4 5 6 7 8 9 10 11 12
No. electrons removed
log
IE
Na
2,8,1
Successive ionisation energies
0 1 2 3 4 5 6 7 8 9 10 11 12
No. electrons removed
log
IE
Na
Successive ionisation energies
0 1 2 3 4 5 6 7 8 9 10 11 12
No. electrons removed
log
IE
Na
Successive ionisation energies
0 1 2 3 4 5 6 7 8 9 10 11 12
No. electrons removed
log
IE
Na
Successive ionisation energies
0 1 2 3 4 5 6 7 8 9 10 11 12
No. electrons removed
log
IE
Na
Successive ionisation energies
0 1 2 3 4 5 6 7 8 9 10 11 12
No. electrons removed
log
IE
Na
Successive ionisation energies
0 1 2 3 4 5 6 7 8 9 10 11 12
No. electrons removed
log
IE
Na
Successive ionisation energies
0 1 2 3 4 5 6 7 8 9 10 11 12
No. electrons removed
log
IE
Na
Successive ionisation energies
0 1 2 3 4 5 6 7 8 9 10 11 12
No. electrons removed
log
IE
Na
Successive ionisation energies
0 1 2 3 4 5 6 7 8 9 10 11 12
No. electrons removed
log
IE
Na
Successive ionisation energies
0 1 2 3 4 5 6 7 8 9 10 11 12
No. electrons removed
log
IE
Na
Successive ionisation energies
0 1 2 3 4 5 6 7 8 9 10 11 12
No. electrons removed
log
IE
Na
Successive ionisation energies
0 1 2 3 4 5 6 7 8 9 10 11 12
No. electrons removed
log
IE
Na
Successive ionisation energies
0 1 2 3 4 5 6 7 8 9 10 11 12
No. electrons removed
log
IE
Na
Successive ionisation energies
0 1 2 3 4 5 6 7 8 9 10 11 12
No. electrons removed
log
IE
Na
Successive ionisation energies
0 1 2 3 4 5 6 7 8 9 10 11 12
No. electrons removed
log
IE
Na
Successive ionisation energies
0 1 2 3 4 5 6 7 8 9 10 11 12
No. electrons removed
log
IE
Na
Successive ionisation energies
0 1 2 3 4 5 6 7 8 9 10 11 12
No. electrons removed
log
IE
Na
Successive ionisation energies
0 1 2 3 4 5 6 7 8 9 10 11 12
No. electrons removed
log
IE
Na
Successive ionisation energies
0 1 2 3 4 5 6 7 8 9 10 11 12
No. electrons removed
log
IE
Na
Successive ionisation energies
0 1 2 3 4 5 6 7 8 9 10 11 12
No. electrons removed
log
IE
Na
Successive ionisation energies
0 1 2 3 4 5 6 7 8 9 10 11 12
No. electrons removed
log
IE
Na
Successive ionisation energies
0 1 2 3 4 5 6 7 8 9 10 11 12
No. electrons removed
log
IE
Na
Successive ionisation energies
0 1 2 3 4 5 6 7 8 9 10 11 12
No. electrons removed
log
IE
Na
2,8,1
Successive ionisation energies
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IE
Si
2,8,4
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IESuccessive ionisation energies
Si
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IESuccessive ionisation energies
Si
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IESuccessive ionisation energies
Si
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IESuccessive ionisation energies
Si
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IESuccessive ionisation energies
Si
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IESuccessive ionisation energies
Si
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IESuccessive ionisation energies
Si
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IESuccessive ionisation energies
Si
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IESuccessive ionisation energies
Si
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IESuccessive ionisation energies
Si
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IESuccessive ionisation energies
Si
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IESuccessive ionisation energies
Si
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IESuccessive ionisation energies
Si
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IESuccessive ionisation energies
Si
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IESuccessive ionisation energies
Si
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IESuccessive ionisation energies
Si
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IESuccessive ionisation energies
Si
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IESuccessive ionisation energies
Si
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IESuccessive ionisation energies
Si
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IESuccessive ionisation energies
Si
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IESuccessive ionisation energies
Si
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IESuccessive ionisation energies
Si
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IESuccessive ionisation energies
Si
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IESuccessive ionisation energies
Si
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IESuccessive ionisation energies
Si
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IESuccessive ionisation energies
Si
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IESuccessive ionisation energies
Si
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
No. electrons removed
log
IESuccessive ionisation energies
Si
2,8,4
Factors Affecting Ionisation Energy
Li
First ionisation
energy
(kJ/mol)
520 419
Ionisation energy decreases when the atom becomes larger because the electrostatic attraction between electrons and protons depends on the distance between the two
the larger the distance the weaker the attraction.
K
Factors Affecting Ionisation Energy
First ionisation
energy
(kJ/mol)
738 590
As the atom gets larger it will also have more energy levels that are full of electrons reduce the electrostatic attraction between protons and electrons. This is called ELECTRON SHIELDING. Hence the ionisation energy will decrease
Mg Ca
Factors Affecting Ionisation Energy
ionisation energy
(kJ/mol)
Ionisation energy increases as the charge on the nucleus increases because the electrostatic attraction between the electrons and protons increases.
10p
2081 7737
12p
Factors Affecting Ionisation Energy- SummaryThe value of the ionisation energy will:↑ as Z↑ because the electrostatic
attraction between the electrons and protons increases.
↓ as size of atom ↑ because the larger the distance between electrons and protons the weaker the electrostatic attraction.
because more full energy levels (ELECTRON SHIELDING). reduce the electrostatic attraction between protons and electrons.
Variation in 1st Ionisation Energy Across a Period
Question: Predict the trend in value of 1st IE for
period 2 (LiNe) by sketching a graph and giving a reason
Variation in 1st Ionisation Energy Across a Period
0
500
1000
1500
2000
2500
Li Be B C N O F Ne
Period 2
Fir
st IE
(kJ
/mo
l)
General Trend:
As Z increases the 1st IE increases as the electrons are being removed from the same shell i.e shielding is constant and the size of the atom decreases due to increased nuclear charge.There are 2 exceptions to the general trend:
BeB and NO
Variation in 1st Ionisation Energy Across a Period
Be B due to the existence of SUB-
SHELLS within the energy shells.
These are known as s,p,d and f sub-shells.
The s sub-shell contains a maximum of 2 electrons
The p sub-shell contains a maximum of 6 electrons
Beryllium has an electronic configuration of 1s2 2s2
Boron has an electronic configuration of 1s2 2s2 2p1
The outer electron in boron is removed from a p- orbital which is higher in energy than the s- orbital outer electron in beryllium
Note: higher energy electrons require less energy (i.e .are easier) to remove.
Variation in 1st Ionisation Energy Across a PeriodN O Within the sub-shells are found “orbitals” An orbital can only hold a maximum of two electrons
The mutual repulsion between the pair of electrons in oxygen means that less energy is required to remove one of them from the atom, hence lowering the first ionisation energy.
Nitrogen is 1s2 2s2 2p3
all p electrons are unpaired
Oxygen is 1s2 2s2 2p4
pairing occurs for the first time
px py pz
↑ ↑ ↑
px py pz
↑↓ ↑ ↑
Variation in 1st Ionisation Energy Across a Period - Summary
General Trend:As Z increases the 1st IE increases as the electrons are being removed from the same shell i.e shielding is constant and the size of the atom decreases due to increased nuclear charge.
BeBThe outer electron in boron is removed from a p-orbital which is higher in energy than the s-orbital outer electron in beryllium, therefore, it is easier to remove and the first ionisation energy is lower.
N ONitrogen is 1s2 2s2 2p3
Oxygen is 1s2 2s2 2p4
The mutual repulsion between the pair of electrons in the 2p orbitals in oxygen means that less energy is required to remove one of them from the atom than the unpaired 2p electrons in nitrogen, hence lowering the first ionisation energy.
Variation in 1st Ionisation Energy Across a Period - Summary
Period 3 follows the same pattern as period 2 and is explained in the same way
Ionisation energies provide evidence for the presence of shells and orbitals in atoms
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