Question

An atom has the following electron configuration.

Answer 1

Answer: The number of valence electron in the given atom are 5

Explanation:

Valence electrons are defined as the electrons which are present in the outermost shell of an atom. Outermost shell has the highest value of 'n' that is principal quantum number.

For the given electronic configuration:  $1s^22s^22p^63s^23p^64s^23d^3$

When an element belongs to d-block, the number of valence electrons are present in $ns,np\text{ and }(n-1)d$ orbitals

Here, n = 4

The electrons in '4s' orbital = 2

The electrons in '3d' orbital = 3

Number of valence electrons = 2 + 3 = 5

Hence, the number of valence electron in the given atom are 5

Answer 2

Answer:

5

Explanation:

The valence electrons are the electrons that are located in the outermost shel of an atom.

Writing the configuration properly, we have:

                         1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d³

In this atom, there is a total number of 23 electrons. This is a transition metal.

The 4s and 3d orbitals are in the outermost energy levels and so their electrons are valent.