What is atomic number? - Science

What is atomic number?

One Line Answer

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]

Chapter 4 Atomic Structure
Evaluation | Q VII. 3. | Page 52

With the help of given Table, find out the mass number of sulphur atom.

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
Name of Element	Symbol	Atomic Number	Number of protons	Number of Neutrons	Number of Electrons	K	L	M	N	Valency
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

Define the following form:

Atomic number

From the symbol `""_12^24"Mg"`
, state the mass number, the atomic number and electronic configuration of magnesium.

What is meant by the 'atomic number of an element'?

What are orbits or shells of an atom?

Draw the structure of the following atoms showing the nucleus containing – protons, neutrons and the orbits with the respective electron:

Isotopes of hydrogen [1₁H, 2₁H, 3₁H]

K and L shells can accommodate a maximum of 2 and 8 electrons respectively.

If an atom has 6 electrons in its outermost shell, it is inert.

What are the letters A, Z, and X stand for?

An element has 2 electrons in its N shell.

What is its atomic number?