Fill in the missing information in the following table. Name Symbol Atomic Number ( Z ) Mass Number ( A ) Number of Neutrons Number of Electrons Oxygen O 8 16 8 16 8 8 3 7 undefined Beryllium 9 12 24 12 25

The atomic number of an atom is the number of protons in the nucleus of the atom. Also, the atomic number is numerically equal to the number of electrons found in an atom. Mass number is the sum of number of protons and neutrons present in an atom. Therefore, the given table can be completed as, Name Symbol Atomic Number ( Z ) Mass Number ( A ) Number of Neutrons Number of Electrons Oxygen O 8 16 8 16 8 8 Lithium undefined 3 7 4 3 Sulphur undefined 16 34 18 16 Beryllium undefined 4 9 5 4 Magnesium undefined 12 24 12 12 Magnesium undefined 12 25 13 12

E M B I B E

Physical Science Class 9>Chapter 9 - What is inside the Atom?>Let us Improve our learning>Q 3

HARD

9th Telangana Board

IMPORTANT

Earn 100

Give the main postulates of Bohr's model of an atom.

Important Questions on What is inside the Atom?

MEDIUM

9th Telangana Board

IMPORTANT

Physical Science Class 9>Chapter 9 - What is inside the Atom?>Let us Improve our learning>Q 4

State the valency of magnesium and sodium.

HARD

9th Telangana Board

IMPORTANT

Physical Science Class 9>Chapter 9 - What is inside the Atom?>Let us Improve our learning>Q 1

Compare the sub-atomic particles electron, proton and neutron.

HARD

9th Telangana Board

IMPORTANT

Physical Science Class 9>Chapter 9 - What is inside the Atom?>Let us Improve our learning>Q 2

What are the limitations of J.J. Thomson's model of the atom?

HARD

9th Telangana Board

IMPORTANT

Physical Science Class 9>Chapter 9 - What is inside the Atom?>Let us Improve our learning>Q 3

Define valency by taking examples of nitrogen and boron.

MEDIUM

9th Telangana Board

IMPORTANT

Physical Science Class 9>Chapter 9 - What is inside the Atom?>Let us Improve our learning>Q 4

What is the main difference among the isotopes of the same element?

MEDIUM

9th Telangana Board

IMPORTANT

Physical Science Class 9>Chapter 9 - What is inside the Atom?>Let us Improve our learning>Q 5

If undefined, what would be the valency of the element?

HARD

9th Telangana Board

IMPORTANT

Physical Science Class 9>Chapter 9 - What is inside the Atom?>Let us Improve our learning>Q 6

Fill in the missing information in the following table.

Name	Symbol	Atomic Number ( $Z$ )	Mass Number ( $A$ )	Number of Neutrons	Number of Electrons
Oxygen	${}_{8}^{16}O$	$8$	$16$	$8$	$8$
		$3$	$7$
	undefined
Beryllium			$9$
		$12$	$24$
		$12$	$25$