Questions from Inside the chapter

Class 9
Chapter 4 Class 9 - Structure of Atom

## (i) Chlorine

• Atomic number of chlorine = 17
• Electronic configuration of chlorine is - 2, 8, 7
• Number of valence electrons = 7

• Since atom has 7 valence electrons it is easier for the atom to gain 1 electron to achieve an octet.

Valency of atoms gaining 1 electron = 1

Therefore, Valency of chlorine = 1

## (ii) Sulphur

• Atomic number of Sulphur = 16
• Electronic configuration of sulphur is - 2, 8, 6
• Number of valence electrons = 6

• Since the atom has 6 valence electrons it is easier for it to gain 2 electrons to achieve an octet .

Valency of atoms gaining 2 electrons = 2

Therefore, Valency of sulphur = 2

## (iii) Magnesium

• Atomic number of magnesium = 12
• Electronic configuration of magnesium is - 2, 8, 2
• Number of valence electrons = 2

• Since the atom has 2 valence electrons it is easier for it to lose 2 electrons to achieve an octet .

Valency of atoms losing 2 electrons = 2

Therefore, Valency of magnesium = 2

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