Question

2 The electronic configuration of an element is
(2,5). Hence its valency is
a.2.
b.3
C. 4.
d. 1​

Answer 1

Answer:

Given 2,8,7 in this first shell can have 2 electrons where as second shell can have 8 electrons 2 in s orbital and 6 in p orbital.

Hence remaining 7 must be only in third shell as third shell has capacity of 18 electrons.

Here in valence shell we have 7 electrons in which 2 are in s orbital and 5 are in p orbital in which 1 is unpaired. Hence valency electrons is 7 for atomic number 17 that is chlorine and valency is 1 as it has to get one electron to get octet configuration.

Answer 2

The valency of the element with electronic configuration (2, 5) is b. 3.

Explanation:

• Valency is the measure of the combining capacity of atoms or molecules.

• Elements in the same group of the periodic table have the same valency. The valency of an element is related to how many electrons are in the outer shell.

• The number of bonds that an atom forms in order to make a compound is expressed by the valency of the element.

• A valence electron is the number of electrons in the outermost shell of an atom.
• Here, the electronic configuration is (2, 5) which means an atomic number of 7 i.e. Nitrogen ($N$).
• Valence electrons here are 5 which is in L-shell.
• Valency is the needed electrons for completing octet, here it is 3.