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Tamil Nadu Board of Secondary EducationSSLC (English Medium) Class 7

What is atomic number? - Science

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Question

What is atomic number?

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Solution

The number of electrons or protons in an atom is called the atomic number of that atom. It is represented by the letter Z.

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Chapter 4: Atomic Structure - Evaluation [Page 52]

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Samacheer Kalvi Science - Term 1 [English] Class 7 TN Board
Chapter 4 Atomic Structure
Evaluation | Q VII. 3. | Page 52

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Composition of Atoms of the First Eighteen Elements with Electron Distribution in Various Shells
Name of Element Symbol Atomic Number Number of protons Number of Neutrons Number of Electrons Distribution of Electrons Valency
K L M N
Hydrogen H 1 1 - 1 1 - - - 1
Helium He 2 2 2 2 2 - - - 0
Lithium Li 3 3 4 3 2 1 - - 1
Beryllium Be 4 4 5 4 2 2 - - 2
Boron B 5 5 6 5 2 3 - - 3
Carbon C 6 6 6 6 2 4 - - 4
Nitrogen N 7 7 7 7 2 5 - - 3
Oxygen O 8 8 8 8 2 6 - - 2
Fluorine F 9 9 10 9 2 7 - - 1
Neon Ne 10 10 10 10 2 8 - - 0
Sodium Na 11 11 12 11 2 8 1 - 1
Magnesium Mg 12 12 12 12 2 8 2 - 2
Aluminium Al 13 13 14 13 2 8 3 - 3
Silicon Si 14 14 14 14 2 8 4 - 4
Phosphorus P 15 15 16 15 2 8 5 - 3.5
Sulphur S 16 16 16 16 2 8 6 - 2
Chlorine Cl 17 17 18 17 2 8 7 - 1
Argon Ar 18 18 22 18 2 8 8   0

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Atomic number


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, state the mass number, the atomic number and electronic configuration of magnesium.


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What is its atomic number?


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