Grade 9 : The Periodic Table

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KITSO is KNOWLED
PHYSICAL SCIENCES
MATTER AND MATERIALS
THE PERIODIC TABLE

2. By the end of this lesson you should be able to:
• Understand and use periodic table
• Define the meaning of atom and element
• Display understanding that different atoms are made of different atoms.
• Give atomic number, number of electrons and mass number of the element.
• Calculate number of neutrons in an element.
• Understand the arrangement of elements in a periodic table.
OBJECTIVES

3. • An element is a pure substance that is made of a very tiny particles called
atoms.
• Atoms are the smallest units that make the elements.
• There are 114 known elements, and they are all listed in a periodic table.
• Elements are represented by their chemical symbols in a periodic table.
THE PERIODIC TABLE

4. THE PERIODIC TABLE
The Periodic Table

5. Representation of atom in a periodic table.
THE PERIODIC TABLE
Z
A
Atomic mass number
Chemical symbol for element
Atomic number

6. Chemical Symbols
• Consists of one or two letters
• Examples:
O – Oxygen
H – Hydrogen
Na – Sodium
Cl - Chlorine
THE PERIODIC TABLE

7. • Atomic number (A) = number of protons in the nucleus of an atom.
• Atomic number = number of electrons in a neutral atom.
• Mass number (Z) = number of protons (A) + number of neutrons (N)
• Number of neutrons = mass number – atomic number
N = Z - A
THE PERIODIC TABLE

8. EXAMPLE
12
6
Atomic number = number of protons = 6
Number of electrons = 6
Mass number = 12
Number of neutrons = 12 – 6
= 6
Carbon

9. Arrangement of elements in the Periodic Table.
The elements in the Periodic Table are arranged in groups and periods.
Groups
• Are the vertical columns.
• They are numbered from 1 to 18
• Elements in the same group behave in a similar way.
THE PERIODIC TABLE

10. Periods
• Run horizontally, in rows.
• There are seven periods of elements in the periodic table.
• The atomic numbers of elements increase by one as you go across the
periods ( from left to right)
THE PERIODIC TABLE

11. THE PERIODIC TABLE

12. THE PERIODIC TABLE

13. 1. Give names of the following chemical symbols.
a) N
b) Ar
c) Ne
d) Mg
e) Al
EXERCISE

14. 2. For each of the following elements give the number of protons, neutron and
mass number.
a) N
b) Ar
c) Ne
d) Mg
e) Al
EXERCISE

15. 3. Study the Periodic Table in slide 4.
a) How many groups are there in the Periodic Table?
b) How many periods are there?
c) What elements are in the same group as oxygen?
d) How many elements are presented in the Periodic Table?
EXERCISE

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