Trends In The Periodic Table
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1Trends in the Periodic Table
Text reference: pg. 50 - 58
1) Draw a line in the middle of a piece of graph paper, separating the
First
Atomic
page into top and bottom. On the top, plot a graph of ionization
Atomic
Element
ionization
radius
energy (y-axis) vs. atomic number (x-axis). On the bottom plot a
number
symbol
energy
(pm)
separate graph of atomic radius vs. atomic number. For each
(kJ/mol)
graph connect successive dots with straight lines. Also, ensure
1
H
1312
32
that identical atomic numbers are plotted on the same vertical
2
He
2372
31
position on the sheet (i.e. atomic number 1 in the top graph should
3
Li
520
123
be on the same line as atomic number 1 in the bottom graph).
4
Be
899
90
5
B
801
82
2) Examine your graph of ionization energy (IE) vs. atomic number.
6
C
1086
77
a) Which elements are found at the main peaks on your graph
7
N
1402
75
(there should be 3)? What do these elements have in common?
8
O
1314
73
b) Which elements are found at the main valleys on your graph
9
F
1681
72
(there should be 3)? What do these elements have in common?
10
Ne
2081
71
11
Na
496
154
3) Examine your graph of atomic radius verses atomic number.
a) Which elements are found at the peaks on your graph? What
12
Mg
738
136
do these elements have in common?
13
Al
578
118
b) Which elements are found at the valleys on your graph? What
14
Si
786
111
do these elements have in common?
15
P
1012
106
16
S
1000
102
4) How are atomic radii and ionization energy related (i.e. as atomic
17
Cl
1251
99
radius increases, what happens to the ionization energy)?
18
Ar
1521
98
19
K
419
203
5) Generally, as you go from left to right across a period on the
20
Ca
590
174
periodic table, what happens to atomic radius? What about IE?
6) Generally, as you go down a group in the periodic table, what happens to atomic radius and IE?
+
+
7) When Na forms an ion it loses its outer electron to become Na
. Draw B-R diagrams for Na and Na
.
+
What element does Na
resemble (with respect to its electron arrangement)? In general, which group’s
electron configuration do the alkali metals resemble when they form ions (i.e. lose an outer electron)?
8) Why does radius increase as you go down a group (hint: think of B-R diagrams)? Why would an
increase in radius make it easier to lose an outer electron (i.e. give a lower ionization energy)?
9) What happens to the number of protons in the nucleus as you go across a period? Use this to explain the
trends in atomic radius and ionization energy across a period.
10) Pages 50 and 58 have diagrams showing trends in the periodic table. There is one group that is usually
ignored because it does not follow these trends. Which group is usually ignored?
11) Define electron affinity. In which corner of the periodic table is it highest? Explain why this is so.
12) Define Electronegativity. Where on the periodic table is it highest? Explain why this is the case.
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