CHEMISTRY FORM 4 KSSM CHAPTER 4 : THE PERIODIC TABLE OF ELEMENTS (THE DEVELOPMENT OF PERIODIC TABLE)

1. CHEMISTRY FORM 4 KSSM
CHAPTER 4 : THE PERIODIC TABLE OF ELEMENTS
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CHEMISTRY FORM 4
KSSM
CHAPTER 4 :
THE PERIODIC TABLE
OF ELEMENTS
PREPARED BY : ESTHER ANNE ANAK RANDI

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4.1 Development of Periodic Table of Elements
4.1.1 Describing the historical development
- Describe the contributions of scientists in the historical development of the Periodic Table
The Periodic Table of Elements classifies known chemical elements in a table according to
certain characteristics. Many theories were explained by scientist before the modern Periodic
Table of Elements were produced. What were those theories? Do you know the scientists
involved in the development of Periodic Table of Elements?
Lavoisier’s Periodic Table
Group I Group II Group III Group IV
Oxygen Sulphur Arsenic Calcium oxide
Nitrogen Phosphorus Bismuth Barium oxide
Hydrogen Carbon Cobalt Silicon(IV) oxide
Light Chlorine Lead Magnesium oxide
Heat Fluorine Zinc, Nickel, Tin, Silver Aluminium oxide
• Lavoisier classified elements according to certain groups such as gases, non-metals,
metals and metal oxides. However, his classification was less accurate because he
also classified light, heat (which are not elements) and a few compounds into the
groups as elements.
• Besides, there were several elements that were classified into the same group but
showed different chemical properties.
Antoine Lavoisier
(1743 - 1794)

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• Dobereiner classified elements with the same chemical properties into
group of three called triads.
• Discovered the relationship between the relative atomic mass ( r.a.m.) of
elements in each triad.
• He found that the r.a.m of the element in the middle of each triad is
approximately equal to the average of the total r.a.m of the other two
elements.
• Dobereiner found that the atomic mass of strontium atom, Sr was similar
to the average mass of calcium atom, Ca and barium atom, Ba. These
elements had the same chemical properties.
• A similar condition occurred with chlorine, Cl, bromine, Br and iodine, I.
• However, Dobereiner’s classification was limited to several elements only.
• Still, the classification showed the relationship between the chemical
properties of elements and atomic mass.
Johann W. Dobereiner
(1780 - 1849)

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• Newlands arranged elements according to their increasing atomic
masses/nucleon number.
• He arranged seven elements in a row because he found that the chemical and
physical properties of the first element recurred at every eighth element.
• He named the arrangement as the Law of Octaves.
• The Law of Octaves had only been conformed by the first 17 elements.
• However, the recurrence in properties of the eighth element showed the
presence of periodic pattern in the properties of elements.
John Newlands
(1837 - 1898)

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Meyer plotted the graph of atomic volume against atomic mass of elements. He found
that the elements at equivalent positions on the curve of the graph had similar
chemical properties. For example, referring to the alkali metals such as lithium, sodium,
potassium and rubidium that were located at the peaks of the curve. Meyer also proved
the recurrence in properties of elements similar to Newlands.
Lothar Meyer
(1830 - 1895)

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Reference : https://corrosion-doctors.org/Periodic/Periodic-Mendeleev.htm
Mendeleev arranged the elements according to their increasing atomic
masses. Only elements with similar chemical properties were arranged in the
same vertical columns. He had left several empty spaces in his periodic table to
be filled by elements, yet to be discovered. He was successful in predicting the
properties of undiscovered elements based on the properties of elements
located above and below an element in the table.
Dmitri Mendeleev
(1834 - 1907)

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• Moseley studied the frequencies of X-ray released by various elements
and eventually found a relationship between the X-ray spectrum and
proton numbers. He proposed that each element ought to have its own
proton number.
• Then, he arranged the elements in the Periodic Table of Elements
according to their increasing proton numbers.
• Moseley also left empty spaces in his periodic table like Mendeleev and
successfully predicted four elements, namely technetium, Tc,
promethium, Pm, hafnium, Hf and rhenium, Re which were discovered
later.
Henry Moseley
(1887 - 1915)

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4.1.2 Deduce the basic principle of arrangement of elements in the Periodic Table
- Identify groups and periods in the Periodic Table
- State the basic principle of arranging the elements in the Periodic Table from their proton
numbers.
Elements in the Periodic Table of Elements are arranged in ascending order of proton numbers, ranging
from 1 to 118. Elements with similar chemical properties are placed in the same vertical columns.
Several new elements which were discovered such as nihonium, Nh, , tennessine, Ts and oganesson, Og
were added into Period 7 of the Periodic Table of Elements.

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Elements Symbol Named after
Nihonium Nh Kosuke Morita, who led a group of researchers that discovered element
113, speaks at a press conference at in Tokyo on June 9. The name
nihonium stems from the fact that element 113 was discovered in
Japan, and Nihon is one way to say the country's name in Japanese
https://www.chemicool.com/elements/nihonium.html
Moscovium Mc Moscovium was discovered in 2003 and officially announced on Feb. 2,
2004. It was created and announced by scientists at the Joint Institute
for Nuclear Research in Dubna, Russia, and scientists at the Lawrence
Livermore National Laboratory in the United States
https://www.chemicool.com/elements/moscovium.html
Tennessine Ts Hamilton initially proposed the name tennessine to honor the state
where three of the participants – Vanderbilt, Oak Ridge and the
University of Tennessee – are located. The name was agreed upon by
the entire team, which submitted it to IUPAC.
The name is spelled tennessine instead of tennessium because the new
element is classified as a halogen-like chlorine and fluorine. Halogens are
given names that end in the suffix “-ine”.
https://news.vanderbilt.edu/2016/11/30/tennessine-approved-as-name-of-
newly-discovered-element/
Oganesson Og The element is named after the Russian Professor Yuri Oganessian, for his
pioneering contributions to transactinoid elements research.
https://www.chemicool.com/elements/oganesson.html

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4.2 THE ARRANGEMENT OF ELEMENTS IN THE MODERN PERIODIC TABLE OF ELEMENTS
4.2.1 Describe briefly the modern Periodic Table of Elements
4.2.2 Generalise the relationship between the proton number and the position of elements in the
modern Periodic Table of Elements.
1. The modern Periodic Table of Elements is a form of systematic classification of elements in
ascending order of proton numbers from left to right and from top to bottom.
2. The arrangement of elements is discussed from the aspects of groups, periods, proton
number and electron arrangement.
3. The Periodic Table is a classification whereby elements with the same chemical properties
are placed in the same groups. This makes the study of chemistry of these elements easier
and more systematic.
4. The vertical columns in the Periodic Table of Elements are called Groups.
5. There are 18 groups in the Periodic Table of Elements. The number of valence electrons will
determine the position of the group of an element.
6. Figure 4.2 shows the position of the group of an element based on the number of valence electrons
Valence electrons :
Electrons in the
outermost occupied shell

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7. The horizontal rows in the Periodic Table of Elements are called Periods.
There are seven periods in the Periodic Table of Elements.
8. The number of shells filled with electrons will determine the position of an element in a period.
9. Table below explains the relationship between the proton number and the position of an element
in the Periodic Table of Elements based on the aspects of groups and periods.
Element
Proton
number
Electron arrangement
Valence
electron
Group
Number of
shells filled
with electrons
Period
Lithium, Li 3
Calcium, Ca 20
Aluminium, Al 13

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Silicon, Si 14
Nitrogen, N 7
Oxygen, O 8
Bromine, Br 35

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Krypton, Kr 36

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10. Each member of the group shows similar chemical properties although their physical
properties such as density, melting point and colour may show a gradual change when
descending down the group.
References :
https://www.thoughtco.com/color-on-the-periodic-table-
608827#:~:text=Colored%20tables%20are%20important%20because,share%20chemical%20and%20physical%20pr
operties.&text=The%20valence%20periodic%20table%20uses,valence%20state%20for%20each%20element.
https://www.ducksters.com/science/chemistry/lanthanides_and_actinides.php
Group 1 : Alkali Metals
Group 2 : Alkali Earth Metals
Group 17 : Halogens
Group 18 : Noble gases
Group 3 - 12 : Transition metals
Group 15, 16 and 17 :
Non metals
Group 14 : Non metals
& Metalloids

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Periods
Period 1 : 2 elements
Period 2 : 8 elements
Period 3 : 8 elements
Period 4 : 18 elements
Period 5 : 18 elements
Period 6 : 32 elements
Period 7 : 32 elements

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Exercise 1
The Electron Arrangement of Elements in the Periodic Table
1. Table below shows the electron arrangement of the elements with proton numbers 1 to 20.
Group
1 2 13 14 15 16 17 18
Period
1
H
1
He
2
2
Li
2.1
Be
2.2
B
2.3
C
2.4
N
2.5
O
2.6
F
2.7
Ne
2.8
3
Na
2.8.1
Mg
2.8.2
Al
2.8.3
Si
2.8.4
P
2.8.5
S
2.8.6
Cl
2.8.7
Ar
2.8.8
4
K
2.8.8.1
Ca
2.8.8.2
2. All members of the same group have same number of _____________________________.
3. Valence electrons are electrons ________________________________________________.
4. For example,
a) Group 1 elements (Li, Na, K) each has ________ valence electron.
b) Group 2 elements (Be, Mg, Ca) each has ___________ valence electrons.
c) Group 17 elements (F, Cl, Br, I) each has ___________ valence electrons.
5. Except for helium, He, the elements with more than 2 valence electrons(Group 13 to 18), the group
number = 10 + (number of valence electrons)
6. The period number is indicated by the number of ________________________________________.
For example :
a) Elements in Period 1 (H and He) each has only ______ electron shell filled with electrons.
b) Elements in Period 2 (Li, Be, B, C, N, O, F, Ne) each has ______ electron shells filled with
electrons.
c) Elements in Period 3 (Na, Mg, Al,Si, P, S, Cl, Ar) each has ______ electron shells filled with
electrons.
d) Elements in Period 4 (K and Ca) each has ______ electron shells filled with electrons.
7. All elements of the same period have the same __________________________________________.

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Exercise 2
The diagram below shows the chemical symbols which represent elements X, Y and Z.
𝑋
11
23
𝑌
6
12
𝑍
19
39
a) Explain how to determine the position of element X in the Periodic Table.
• The proton number of element X is _______ and the number of electrons in atom X is
_______.
• The number of electrons in atom X is ___________.
• The electron arrangement of atom X ___________.
• Element X is located in Group _____ because atom X has ______________________.
• Element X is in Period ______ because atom X has _____________ shells occupied with
electrons.
b) State the position of element Y in the Periodic Table.
______________________________________________________________________________
c) Explain how to determine the position of element Y in the Periodic Table.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
d) Which of the above elements show the similar chemical properties? Explain your answer.
• Element _________ and Element ________.
• Electron arrangement of atom ______ is _______________ and the electron
arrangement of atom ________ is ________________.
• Atom ________ and ___________ have the same number of _____________________.