Name: Methods of Representing Electronic Configuration
Uploaded: 2019-07-19
Duration: 11 min 48 s
Description: The electron configuration of an atom is the representation of the arrangement of electrons distributed among the orbital shells and subshells. Learn more.

Question

Give the sequence in which the energy levels in an atom are filled with electrons. Write the electronic configurations for the elements of atomic number

6, 11, 17

,

25

and from this decide to which group in the periodic table each element belongs.

Accepted Answer

The energy of orbitals is compared by $(n + l)$ rule and in case $(n + l)$ values are equal the lower value of $n$ will have lower energy.

$\begin{matrix} energy & 2 p & < & 3 s \\ n & 2 & 3 \\ l & 1 & 0 \\ n + 1 & 3 & 3 \end{matrix}$

The orbitals that will be filled in $n^{th}$ period are,

$ns np (n - 1) d (n - 2) f (n - 3) g . . . . .$

The orbital to which last electron enters give information about the block of element.

For $s$ block elements group number is equal to electron in $s$ orbital of valence shell and for $p$ block element group number is equal to the number of electron in $p$ orbital of valence shell $+ 12$ .

For $d$ block element group number is equal to the number of electron in $ns$ and $(n - 1) d$ orbital where, $n$ is valence shell.

(a) Atomic number $= 6$

Electronic configuration $1 s^{2} 2 s^{2} 2 p^{2}$

Last electron enters to $p$ orbital and hence, element belongs to $p$ block.

Group $= 12 + 2 = 14$

(b) Atomic number $= 11$

Electronic configuration $1 s^{2} 2 s^{2} 2 p^{6} 3 s^{1}$

Last electron enters to $s$ orbital and hence, element belongs to $s$ block.

Group $= 1$

(c) Atomic number $= 17$

Electronic configuration $1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{5}$

Last electron enters to $p$ orbital and hence, element belongs to $p$ block.

Group $= 12 + 5 = 17$

(d) Atomic number $= 25$

Electronic configuration $1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6} 3 d^{5} 4 s^{2}$

Last electron enters to $d$ orbital and hence, element belongs to $d$ block.

Group $= 5 + 2 = 7$

Give the sequence in which the energy levels in an atom are filled with electrons. Write the electronic configurations for the elements of atomic number $6, 11, 17$ , $25$ and from this decide to which group in the periodic table each element belongs.

Important Questions on Atomic Structure and the Periodic Table

Learn and Prepare for any exam you want !

Give the sequence in which the energy levels in an atom are filled with electrons. Write the electronic configurations for the elements of atomic number 6, 11, 17, 25 and from this decide to which group in the periodic table each element belongs.

Important Questions on Atomic Structure and the Periodic Table

Learn and Prepare for any exam you want !

Give the sequence in which the energy levels in an atom are filled with electrons. Write the electronic configurations for the elements of atomic number $6, 11, 17$ , $25$ and from this decide to which group in the periodic table each element belongs.