Question

Write the electronic configuration of the elements given below:
A (At.No.=9) , B(At.No.=12) ,C(At.No.=29) ,D(At.No.=54) , E(At.No.=58) , F(At.No.=90)
(a) Predict the period , group number and block to which they belong. (b)Classify them as representative elements , noble gases , transition and inner
trasition elements

Answer 1

Answer:

Atomic number 29 has the electronic configuration - [Ar]4s13d10 . Since the last electrons enter the d orbital, it is a d- block element.

Explanation:

I hope it will be help you

Answer 2

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(i) Flourine (Atomic number = 9)

Electronic configuration of Flourine is 1s² 2s² 2p⁵

★Highest value of principal quantum number = Period number of the element

$\implies$ Period Number of Flourine = 2

★Number of valence electrons = Group number of the element.

$\implies$ Group number of Flourine = 2+5 = 7

Elements which belong to s and p block are said to representative elements

Group 7 falls in p-block . Hence , Flourine is an representative element.

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(ii) Magnesium (Atomic number = 12)

Electronic configuration of Magnesium = 1s² 2s² 2p⁶ 3s²

Highest value of principal quantum number = 3

$\implies$ Period Number of Magnesium = 3

Number of valence electrons = 2

$\implies$ Group number of Magnesium = 2

Group number two falls in s-block . So , Magnesium is an representative element.

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(iii) Copper (Atomic number = 29)

Electronic configuration of Copper is 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ 3d¹⁰ (Exceptional case)

Highest value of principal quantum number = 4

$\implies$ Period Number of copper = 4

Number of valence electrons = 1e⁻ in 4s + 10 electrons in 3d = 11

$\implies$ Group number of copper = 11

The valence electron is in d shell . So , Copper is an transition element.

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(iv) Xenon (Atomic number = 54)

Electronic configuration of Xenon is 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶

Highest value of principal quantum number = 5

$\implies$ Period Number of Xenon = 5

Number of valence electrons = 10 electrons in 4d + 2 electrons in 5s + 6 electrons in 5p

$\implies$ Group number of Xenon = 18

Group number 18 falls in p-block . So , Xenon is an representative element.

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(v) Cerium (Atomic number = 58)

Electronic configuration of Flourine is 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 5d¹ 6s² 4f¹

Highest value of principal quantum number = 6

$\implies$ Period Number of Cerium = 6

Cerium belongs to f-block . Since it's valence electron is in f .It is an inner transition element .

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(vi) Thorium (Atomic number = 90)

Electronic configuration of Thorium is 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 5d¹⁰ 6s² 4f¹⁴ 6p⁶ 5f⁰ 6d² 7s²

Highest value of principal quantum number = 7

$\implies$ Period Number of Thorium = 7

Thorium belongs to f-block . It is an inner transition element