Download - Unit 2 Electron Conf Part II IE and EA
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General Chemistry 1
MF008
Unit 2: Electronic Structure
Part II: Ionisation Energy & Electron Affinity
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Contd from Part I
If you find the term
Principle Quantum Number (n) it is the same asshell. It determines _______of orbital.
Angular Momentum Number (l) it is the same as
subshells. It determines _________of orbital Magnetic Quantum Number (mf) determines
orientation of ___________in space. Eg: px, py,
pz
Spin Quantum Number (ms) determines theproperty of______________. It has values
either +1/2 or -1/2
size
shape
orbital
electron
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Shell or the
Principle
Quantum
number (n)
Number of subshells
or the Angular
Momentumnumber (l)
Magnetic quantum
number (ml)
Number
Of
orbitals
Number
of
Electrons
1 0 (s) 0 1 2
2 0 (s) 0 1 2
2 1 (p) -1, 0, +1 3 6
3 0 (s) 0 1 2
3 1 (p) -1, 0, +1 3 6
3 2 (d) -2, -1, 0, +1, +2 5 10
4 0 (s) 0 1 2
4 1 (p) -1, 0, +1 3 6
4 2 (d) -2, -1, 0, +1, +2 5 10
4 3 (f) -3, -2, -1, 0, +1, +2, +3 7 14
Summary
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Question
An atom or ion is said to be in excited state if the electronic
configuration does not obey the Aufbau Principle
Electron configuration Excited Yes / No Correct Sequence
1s2
2s2
2p5
3s2
3p5
4s2
3d10
4p6
1s2 2s2 2p5 3s2 3p6
1s2 2s1 2p6 3s2 3p6 4s2
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Ionisation Energy (I.E)
Ionisation Energy is a measure of energy
required to __________ electrons from an
atom.
There are as many I.E. as there are
________________ in an atom.
eg: Na has 11 electrons so it has 11 I.E
that is 1st I.E, 2nd I.E., 3rdI.E and so forth..
remove
electrons
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Factors affecting I.E.
1. Nuclear charge The __________the nuclear charge, the _____________ the
attractive force of the nucleus on the electrons.
=>I.E __________ across a Period for s and p block elements
2. Atomic radius
The _____________the atom, the further is the outer shell electrons andthe _____________is the attractive force of the nucleus, so less energy isrequired.
=>I.E _____________down a Group in the Periodic Table
3. Shielding effect
Lower energy level electrons ____________the outermost electron from theattractive force of the atomic nucleus
=> I.E. _________________ down a Group in the Periodic Table
higher stronger
Increase
largerweaker
decrease
shield
decrease
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First Ionisation Energy (1st I.E)
Definition:
The energy required to remove _______ mole of
__________ from _______ mole gaseous
_____________ to form ____ mole of gaseous positive
ion.
Na(g) Na+(g) + e 1st I.E
Na+(g) Na 2+ (g) + e 2nd I.E
The stronger the pull of nucleus on the electron, the
________ energy needed to pull it out of the atom.
oneelectron one
atom one
greater
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Trend in I.E down group
Value ___________ down group.
Despite the _________ in nuclear charge due to
__________ number of protons in nucleus, the
outer shell electron is easier to remove.
This is due to __________ shielding and greater
_________ from nucleus. Outer electron is held _________ strongly and
thus __________ to remove.
decrease
increase
increase
greater
distanceless
easier
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Example 1
The successive I.E for removal of each electron from anoxygen atom
1310, 3400, 5300, 7500, 11000, 13000, 71300, 84100
There is a big increase in the energy required to removethe ________electron. The first _________electrons areremoved from the second shell (2s and 2p). The
___________electron is removed from the inner firstshell (1s)
=> From values of I.E, we can predict that element isin_____________
7th six
7th
Group 6
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Trend across period
I.E. generally ___________ across periodas __________________ is greater withone extra ____________.
The extra ___________ has gone into thesame ____________ level. So, not muchdifference in _______________ effect.
Increase ______________ makes electron___________ to remove.
increase
Nuclear charge
proton
electronenergy
shielding
attraction
harder
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Example 2
The first eight successive I.E for an element are as follows:
790, 1600, 3200, 4400, 16100, 19800, 23800, 23800
(a) How many electrons are there in the outer shell of theelement?
(a) In which group in the Periodic Table does the element
belong?
(a) Write down the electronic configuration of the element
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Electron Affinity (EA)
EA is the ___________ change when onemol of __________ is added to one mol of
______________ atoms or ions.
Just like IE, there is 1st EA, 2nd EA and so
forth.
Eg: Cl (g) + e Cl- (g)
energy
electron
gaseous
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Change in EA
First EA is usually _________ as energy is
released when an electron is
______________ to the nucleus.
Second EA is always _________ as
energy is required to overcome
electrostatic ___________ and add
another electron to a _________ ion.
negative
attracted
positive
repulsion
negative
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