HL Chemistry
Topic 12
Atomic Structure
Define: ionization energy
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HL Chemistry
Topic 12
Atomic Structure
Trends in Ionization Energy in the Periodic Table
Why do these trends in ionization energy occur?
Background information: Understand the concept of effective nuclear charge
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HL Chemistry
Topic 12
Atomic Structure
Ionization energy increases across the Period
and decreases down the Group
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HL Chemistry
Topic 12
Atomic Structure
But there are issues . . .
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HL Chemistry
Topic 12
Atomic Structure
Write electron configurations for
1Hydrogen
2Helium
3Lithium
Aufbau principle
Pauli exclusion principle
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HL Chemistry
Topic 12
Atomic Structure
Write electron configurations for
4Beryllium
5Boron
6Carbon
Hund’s Rule
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HL Chemistry
Topic 12
Atomic Structure
Recall – the electron configurations for beryllium and boron are as follows
Be
1s22s2
B
1s22s22p1
Write configurations for:
7N
8O
10Ne
Recall – ionization energies decrease down a group
Recall – ionization energies increase across a period
The “dips” between Be and B and again between N and O are evidence for the s,p,d,f
model! Explain:
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HL Chemistry
Topic 12
Atomic Structure
Electron Configuration Worksheets
Each page of this worksheet has space for you to fill out the electron configurations of 4 atoms
or ions. Use the worksheet to write electron configurations for the following elements:
1.
2.
3.
4.
5.
6.
7.
8.
Fluorine
56
Fe
Magnesium - 22
131
I
Potassium – 42
75
Ge
Zirconium – 90
41
Ca2+
How to use this worksheet:
Example: Oxygen – 14
1.
2.
3.
4.
Atom or ion: oxygen -14
No. of: p+ 8 n0 6 e- 8
Write the name of the atom in the space
provided.
Determine the number of protons,
neutrons and electrons.
Fill in the electrons. Recall that
a. each orbital can only hold two
electrons indicated by up and
down arrows
b. add electrons from lowest to
highest energy subshell – fill the
diagram from the bottom up.
c. For equal energy orbitals (example
p orbitals) fill each orbital with an
up electron before adding any
electrons.
Write the electron configuration for the
atom or ion in the space provided.
Write electron configuration below
1s22s22p4
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HL Chemistry
Topic 12
Atomic Structure
Atom or ion: _______________
No. of: p+____ n0 ____ e-____
Atom or ion: _______________
No. of: p+____ n0 ____ e-____
Write electron configuration below
Write electron configuration below
Atom or ion: _______________
No. of: p+____ n0 ____ e-____
Atom or ion: _______________
No. of: p+____ n0 ____ e-____
Write electron configuration below
Write electron configuration below
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HL Chemistry
Topic 12
Atomic Structure
Atom or ion: _______________
No. of: p+____ n0 ____ e-____
Atom or ion: _______________
No. of: p+____ n0 ____ e-____
Write electron configuration below
Write electron configuration below
Atom or ion: _______________
No. of: p+____ n0 ____ e-____
Atom or ion: _______________
No. of: p+____ n0 ____ e-____
Write electron configuration below
Write electron configuration below
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HL Chemistry
Topic 12
Atomic Structure
Using the periodic table (a big help) and writing condensed electron configurations:
example: bromine
The first BIG exception : transition metal ions
The first electrons removed in the ionization process come from the highest energy s orbitals (not
the most recently filled d orbitals). For example cobalt forms both +2 and +3 ions.
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HL Chemistry
Topic 12
Atomic Structure
Practice:
Use the Periodic table to write the condensed electron configuration of the following elements:
a) Si
___________________________
b) S2-
___________________________
c) Rb+
___________________________
d) Se
___________________________
e) Ar
___________________________
f)
___________________________
Nb
g) Zn2+
___________________________
h) Cd
___________________________
i)
___________________________
Sb
The second BIG exception : chromium and copper
Chromium and copper show minor exceptions to the Aufbau principle when filling the 3d orbitals.
The resulting configurations are more energetically stable and therefore occur.
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HL Chemistry
Topic 12
Atomic Structure
Successive Ionization Energies
The following data gives values for the amount of energy required to remove each successive
electron from an atom of magnesium.
Complete – Successive Ionization Energies activity
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HL Chemistry
Topic 12
Atomic Structure
Exercise 12.1
1. The electronic configuration 1s2 2s2 2p6 3s2 3p6 would be found in
A. neon atoms
B. sodium ions
C. sulfide ions
D. chlorine atoms
2. Which one of the following elements has the lowest first ionization energy?
A. Argon
B. Magnesium
C. Sodium
D. Lithium
3. How many 3d electrons are present in the ground state of a cobalt atom?
A. 6
B. 7
C. 8
D. 9
4. The first three ionization energies of aluminium (in kJ mol-1) are 584, 1823 & 2751. The
fourth ionization energy (in kJ mol-1) is most likely to be about:
A. 3000
B. 5000
C. 10 000
D. 100 000
5. The first ionization energy of aluminium is slightly lower than that of magnesium because
A. magnesium has a higher nuclear charge.
B. the outer electron in aluminium is in a p-orbital not an s-orbital.
C. in aluminium the electron is being lost from a doubly filled orbital.
D. the radius of the aluminium atom is greater than the magnesium atom.
6. Which one of the following atoms would have the highest fourth ionization energy?
A. C
B. N
C. Si
D. P
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HL Chemistry
Topic 12
Atomic Structure
7. How many unpaired electrons are there in the Cr
A. 0
B. 1
C. 3
D. 6
3+
ion?
8. Which one of the following would require the most energy for the removal of one more
electron?
A. F–
B. Ne
C. Na+
D. Mg2+
9. Write the complete electron configurations of:
a) Mn
b) S
c) Mg2+
d) Fe3+
e) Cu
10. Arrange the following in order of increasing ionization energy, Li Na Ne N O
11. Do the following
a) Sketch a graph to show how you would expect the successive ionization energies of
silicon to vary with the number of electrons removed.
b) Explain how this provides evidence that the electrons in atoms are arranged in
distinct energy levels.
c) Explain why, within one of these levels, the amount of energy required to remove an
electron varies with the number of electrons removed.
12. Explain why
a) the first ionisation energy of lithium is greater than that of sodium.
b) the first ionisation energy of oxygen is less than that of nitrogen.
c) the first ionisation energy of beryllium is greater than that of boron.
13. A particular metal cation M3+ has the electronic structure [Ar] 3d2.
a) Identify the metal concerned.
b) Write the electronic structure of the metal atom.
c) Explain why the electronic structure of the ion could not be the electronic structure
of a neutral atom.
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HL Chemistry
Topic 12
Atomic Structure
14. The graph below shows the logarithm of the successive ionization energies of a particular
element with atomic number less than or equal to 20.
a) Identify the element.
b) Predict the approximate value of the logarithm of the seventh ionization energy.
c) How would you expect the equivalent successive ionization energies of the element
immediately above it in the periodic table to compare in magnitude?
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HL Chemistry
Topic 12
Atomic Structure
15. The table below gives successive ionization data for a number of elements in kJmol-1.
a)
b)
c)
d)
Which two elements are probably in the same group of the periodic table?
Which element is probably in group 3 of the periodic table? How can you tell?
Which two elements probably have consecutive atomic numbers?
Which element is most probably a noble gas? Give two pieces of evidence for this.
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