Trends in the
Periodic Table
JOHAN
N
@johannwolfgangdobereiner
Helloooooooo!! Just want to know
the trends in the periodic table of
elements
#HelpMeGrade8
#TugsayMahusay
DECODE ME!
 There
will be a question to be posted and a set of
numbers has provided as your guide.
 You are going to decode these numbers in order to
reveal the answer.
 Each number corresponds a letter from the english
alphabet. For 1=A, 2=B, 3=C, 4=D……26=Z and for
0=Space
ATOMIC RADIUS
It pertains to the size of an atom, the half of the distance
between the nuclei of neighboring atoms. In this trend,
the behavior of representative elements decreases in
going from left to right across period. Within a family or
group, it increases from top to bottom.
1, 20, 15, 13, 9, 3, 0, 18, 1, 4, 9, 21, 19
METALLIC PROPERTY
It refers to the level of reactivity of a metal. In this
trend, the behavior of representative elements
decreases in going from left to right across period.
Within a family or group, it increases from top to
bottom.
13, 5, 20, 1, 12, 12, 9, 3, 0, 16, 18, 15, 16, 5,
18, 20, 25
ELECTRONEGATIVITY
It measures the tendency of an atom to attract an
electron. In this trend, the behavior of
representative elements increases in going from left
to right across period. Within a family or group, it
increases from bottom to top.
5, 12, 5, 3, 20, 18, 15, 14, 5, 7, 1, 20, 9, 22, 9,
20, 25
IONIZATION ENERGY
It is the minimum amount of energy required to
remove an electron from a neutral atom in its
gaseous phase. In this trend, the behavior of
representative elements increases in going from left
to right across period. Within a family or group, it
increases from bottom to top.
9, 15, 14, 9, 26, 1, 20, 9, 15, 14, 0, 5, 14, 5,
18, 7, 25
1. ATOMIC RADIUS
It pertains to the size of an atom, the half of the
distance between the nuclei of neighboring
atoms.
ATOMIC RADIUS
Which of the following elements have
high atomic radius?
1. N vs F
2. N vs Al
IONIC RADIUS
Adding electrons
makes an atom bigger,
and taking one away
makes it smaller.
F
Na
F-
+
Na
Which of the following have high
ionic radius?
1. S vs S
-2
2. Ca vs Ca
3. Br vs Kr
+2
2. METALLIC PROPERTY
It refers to the level of reactivity of a metal. Metallic
property of an element depends on how readily it
can lose its electrons.
METALLIC PROPERTY
Which of the following elements
possess high metallic property
1. Ca vs. Rb
2. Na vs. Mg
3. ELECTRONEGATIVITY
 It
refers to the tendency of
an atom to attract an
electron.
 F is the most electronegative
atom
 Noble gases are not
electronegative.
ELECTRONEGATIVITY
Which of the following elements have
high electronegativity?
1. Cl vs. N
2. P vs. Si
4. IONIZATION ENERGY
It is the minimum amount
of energy required to
remove an electron.
IONIZATION ENERGY
Which of the following elements have
high ionization energy?
1. Al vs. S
2. N vs. Si
Activity 1: Does the Atomic Size of the Elements
vary with Atomic Number?
 Objectives:
-
-
Find out the relationship between the atomic
radius of selected elements and their atomic
number.
Describe the change in atomic radius of elements
from Li to F and from Na to Cl.
 Materials:
- Graphing paper
- Pencil
- Ruler
 Procedure:
- Prepare a graph showing atomic radius
plotted against atomic number.
- Study the graph.
Element Atomic
Number
H
Li
Be
B
C
N
O
F
Na
Mg
Al
Si
P
S
Cl
(horizontal)
1
2
4
5
6
7
8
9
11
12
13
14
15
16
17
Atomic Radius
(nm) (vertical)
0.037
0.133
0.089
0.080
0.077
0.074
0.074
0.072
0.157
0.136
0.125
0.117
0.110
0.104
0.099
K
Ca
Ga
Ge
As
Se
Br
Rb
Sr
In
Sn
Sb
Te
I
Cs
19
20
31
32
33
34
35
37
38
49
50
51
52
53
55
0.203
0.174
0.125
0.122
0.121
0.117
0.114
0.216
0.191
0.150
0.141
0.141
0.137
0.133
0.235
 QUESTIONS:
1. What are the elements at the highest points?
At the lowest points?
2. Do you see any cyclic pattern?
3. Describe the change in atomic radius of
elements from Li to F and from Na to Cl. Is this
repeated in other cycles?
4. Give the relationship between atomic number
and atomic size of the elements within one
cycle.
Activity 2: Is Ionization Energy Dependent on Atomic
Number?
 Objectives:
- Look for the recurrence of high or low ionization energy values
in the elements arranged in order of increasing atomic numbers.
- Describe the variation of ionization energy with atomic number.
 Materials:
- Graphing paper
- Pencil
- Ruler

Procedure:
1. Copy the figure (Plot of Ionization energy vs. atomic number)
2. Study the position of each element in the plot and fill in the table with your data.
Atomic number of
elements at the highest
points
Elements at the
highest points
Interval in atomic number between
elements at two successive highest
points
Elements at the
lowest points
Interval in atomic number between
elements at two successive lowest
points
1.
2.
3.
4.
5.
Atomic number of the
elements at the lowest
points
1.
2.
3.
4.
5