6. 2 X2 X e
8 X8 X e
18 X18 X e
Review: Octet Rule
7. P
P
P
N
N
N
N
P
e
e e
e
BERYLLIUM
Full energyFull energy
level?level? YesYes
Full octet?Full octet? NoNo
Needs to gain 6 moreNeeds to gain 6 more
or lose 2 electronsor lose 2 electrons
Review: Octet Rule
11. Try drawing the following atoms
using Lewis dot diagrams
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
Review: Lewis Dot Diagram
12. Group: All
elements in a
group have the
same number of
valence electrons
Period: All
elements in a
period have the
same number of
energy levels
Periodic Table
13. All of the Group 1
elements have
one valence
electron, hence
elements in a
group often have
similar properties
Periodic Table: Group
14. Elements in the same group share similar properties
Metalloidsk Noble Gasesk
Periodic Table: Period
15. Periodic Law:
1. When the elements are arranged in order of increasing atomic mass,
certain sets of properties recur periodically
2. the properties of the elements are periodic functions of their atomic
numbers
Periodic Law
Certain chemical and
physical properties repeat
themselves when the
elements are arranged in
order of increasing atomic
number
16. Periodic Law devised by
Dmitri Mendeleev and
Lothar Meyer in 1869.
Mendeleev produced a
periodic table which
predicted the properties of
8 elements that were not
discovered yet.
Periodic Law: Origins
17. Atoms get smaller
from left to right in a
period
Atoms get larger from
top to bottom in a
group
Periodic Trends: Atomic Radius
18. e
e e
e
P P
P
N
N
N
NP
e
e e
e
P P
P
N
N
N
NP
P
P
P
N
N
N
N
P
e
ee
e
Beryllium Oxygen
When atoms share the same highest energy level, there is a
stronger pull on the electrons when there are more protons
Periodic Trends: Atomic Radius
19. Page 60 #2 a, c, e
Periodic Trends: Atomic Radius
20. Practice:
Using only their location in the periodic table,
rank each of the following sets of elements in
order of increasing atomic size. Explain your
answer in each case.
a)Mg, S, Cl b) Al, B, In
c) Ne, Ar, Xe d) Rb, Xe, Te
e) P, Na, F f) O, S, N
Periodic Trends: Atomic Radius
21. e
e e
e
P P
P
N
N
N
NP
e
e e
e
P P
P
N
N
N
NP
P
P
P
N
N
N
N
P
e
ee
e
Beryllium Oxygen
Which atom has a greater ability to attract
electrons?
Periodic Trends: Electronegativity
22. g2 1 g2 2 g2 4 g2 5 g2 6 g2 7
The closer an atom is to achieving a full octet, the greater its
ability to attract electrons.
Electronegativity is the measure of an atom’s ability to attract
electrons.
Which atom should have the highest
electronegativity? Which is second highest?
Periodic Trends: Electronegativity
23. g2 7
Electrons are closer to the
nucleus = stronger pull on
electrons
Electrons are farther from
the nucleus = weaker pull on
electrons
Stronger
electronegativity
g2 87
Periodic Trends: Electronegativity
24. Page 74 #4 a, b
Periodic Trends: Electronegativity
25. Practice:
Based only on their position in the periodic table,
arrange the elements in each set in order of
increasing electronegativity
a) Li, Br, Zn, La, Si b) P, Ga, Cl, Y, Cs
Periodic Trends: Electronegativity
26. Beryllium
The energy it takes to remove
the outermost electron in an
atom (expressed as kJ/mol)
If the electronegativity is high,
is it harder or easier to remove
an electron? i.e. Does it require
more or less energy?
P
P
P
N
N
N
N
P
e
e e
e
Periodic Trends: Ionization Energy
27. g2 1 g2 2 g2 4 g2 5 g2 6 g2 7
RECAP: An atom’s ability to attract electrons increases as it gets
closer to achieving a full octet
Stronger
electronegativity
RECAP: An atom’s ability to attract electrons increases when its
nucleus is closer to the outermost electrons
Periodic Trends: Ionization Energy
29. Practice:
Based only on their position in the periodic table,
arrange the elements in order of increasing ionization
energy
Li, Br, Zn, La, Si, P, Ga, Cl, Y, Cs
Periodic Trends: Ionization Energy
30. Practice:
Based only on their position in the periodic table,
arrange the elements in order of increasing ionization
energy
ANSWER: Cs, Li, La, Y, Zn, Ga, Si, P, Br, Cl
Periodic Trends: Ionization Energy
31. Practice:
Using only their location in a periodic table, rank each of
the following sets of elements in order of decreasing
ionization energy.
a) Cl, Br, I b) Ga, Ge, Se c) K, Ca, Kr
d) Na, Li, Cs e) S, Cl, Br f) Cl, Ar, K
Periodic Trends: Ionization Energy
34. A measure of the change in energy that occurs when
an electron is added to an atom.
Periodic Trends: Electron Affinity
e
e e
e
P P
P
N
N
N
NP
P
P
P
N
N
N
N
P
e e
e
e
P
e
e
The closer an atom is to
achieving an octet, the
more stable it will become
when an electron is
added.
The resulting increase in
stability causes a release
of energy.
Hence electron affinity
increases from left to right
across a period.
35. Periodic Trends: Electron Affinity
The distance of the valence
electrons from the nucleus
increases going down a
periodic table.
This results in less attraction
for the valence electrons, as
well as any extra electrons
that may be added.
The decreased attraction
results in less energy
released. Thus electron
affinity increases going up a
group in the periodic table.
36. A measure of the change in energy that occurs when
an electron is added to an atom.
Periodic Trends: Electron Affinity
38. Complete pg 60 #4 a), b), c), d)
Which element in each of the following pairs will
have the lower electron affinity? Explain your
answer in each case
a) K or Ca b) O or Li
c) S or Se d) Cs or F
Periodic Trends: Electron Affinity
