(i) Write the electronic configurations of the following ions: (a) H^–(b) Na⁺ (c) O^2–(d) F^–

(ii) What are the atomic numbers of elements whose outermost electrons are represented by (a) 3s¹(b) 2p³ and (c) 3p⁵?

(iii) Which atoms are indicated by the following configurations?

(a) [He] 2s¹ (b) [Ne] 3s² 3p³ (c) [Ar] 4s² 3d¹.

Open in App

Solution

(i) (a) H^– ion

The electronic configuration of H atom is 1s¹.

A negative charge on the species indicates the gain of an electron by it.

∴ Electronic configuration of H^– = 1s²

(b) Na⁺ion

The electronic configuration of Na atom is 1s² 2s² 2p⁶ 3s¹.

A positive charge on the species indicates the loss of an electron by it.

∴ Electronic configuration of Na⁺ = 1s² 2s² 2p⁶ 3s⁰ or 1s² 2s² 2p⁶

(c) O^2– ion

The electronic configuration of 0 atom is 1s² 2s² 2p⁴.

A dinegative charge on the species indicates that two electrons are gained by it.

∴ Electronic configuration of O^2– ion = 1s² 2s² p⁶

(d) F^– ion

The electronic configuration of F atom is 1s² 2s² 2p⁵.

A negative charge on the species indicates the gain of an electron by it.

∴ Electron configuration of F^– ion = 1s² 2s² 2p⁶

(ii) (a) 3s¹

Completing the electron configuration of the element as

1s² 2s² 2p⁶ 3s¹.

∴ Number of electrons present in the atom of the element

= 2 + 2 + 6 + 1 = 11

∴ Atomic number of the element = 11

(b) 2p³

Completing the electron configuration of the element as

1s² 2s² 2p³.

∴ Number of electrons present in the atom of the element = 2 + 2 + 3 = 7

∴ Atomic number of the element = 7

(c) 3p⁵

Completing the electron configuration of the element as

1s² 2s² 2p⁵.

∴ Number of electrons present in the atom of the element = 2 + 2 + 5 = 9

∴ Atomic number of the element = 9

(iii) (a) [He] 2s¹

The electronic configuration of the element is [He] 2s¹ = 1s² 2s¹.

∴ Atomic number of the element = 3

Hence, the element with the electronic configuration [He] 2s¹ is lithium (Li).

(b) [Ne] 3s² 3p³

The electronic configuration of the element is [Ne] 3s² 3p³= 1s² 2s² 2p⁶ 3s² 3p³.

∴ Atomic number of the element = 15

Hence, the element with the electronic configuration [Ne] 3s² 3p³is phosphorus (P).

(c) [Ar] 4s² 3d¹

The electronic configuration of the element is [Ar] 4s² 3d¹= 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹.

∴ Atomic number of the element = 21

Hence, the element with the electronic configuration [Ar] 4s² 3d¹is scandium (Sc).

Suggest Corrections

Similar questions

Write the electronic configurations of the following ions:
(a) $H^{-}$
(b) $N a^{+}$
(c) $O^{2 -}$
(d) $F^{-}$

(ii) What are the atomic numbers of elements whose outermost electrons are represented by
(a) 3 $s^{1}$
(b) 2 $p^{3}$ and
(c) 3 $p^{5}$ ?

Which atoms are indicated by the following configurations?
(a) [He] 2 $s^{1}$
(b) [Ne] 3 $s^{2} 3 p^{3}$
(c) [Ar] 4 $s^{2} 3 d^{1}$

Q. The electron configuration of elements A, B and C are

[H e] 2 s^{1}, [N e] 3 s^{1}

and

[A r] 4 s^{1}

respectively. Which one of the following order is correct for the first ionization potentials

(i n K J m o l^{1})

of A, B and C?

Q. The electronic configurations of four particles A, B, C and D given below:

A	2, 8, 8
B	2, 8, 2
C	2, 6
D	2, 8

Which electronic configuration represents:
(i) magnesium atom?
(ii) oxygen atom?
(iii) sodium ion
(iv) chloride ion?

Q. Select the correct answer:
(i) Which of the following electronic structures is of a metal?
(a) 2, 8, 8
(b) 2,7
(c) 2, 8, 2
(d) 2, 8, 4

(ii) Atomic radii of fluorine and neon in angstrom unit are
(a) 0.72, 13.6
(b) 1.60, 1.60
(c) 0.72, 0.72
(d) none of these

(iii) Configuration of an element is 2, 8, 1. Which of the following statement is true?
(a) Valency of element is 7
(b) Element is diatomic
(c) Element is non-metal
(d) Element forms basic oxide

(iv) Which of the following element has highest electronegativity?
(a) F
(b) H
(c) Ne
(d) Na

The electronic configurations of atoms of three elements A. B and C are (2, 8, 1), (2, 8, 6) and (2, 8, 18, 7) respectively.
Which option classifies the elements A. B and C as metals and non-metals correctly?

Join BYJU'S Learning Program