Question

How many valence electrons does the element plutonium have?

Answer 1

The valence electrons are those electrons which are present in the valence shell of the element. The distribution of electrons takes place by the Aufbau Principle.

Complete step by step answer:
Plutonium is a chemical element with atomic number $94$ and atomic mass $244$ . It is represented by the symbol $Pu$ . It belongs to the actinide series and in appearance it is silvery grey metal.
The distribution of electrons takes place by following the aufbau rule or aufbau principle. According to aufbau rule, the electrons will occupy lower energy available atomic orbitals first before occupying higher energy levels.
So, electronic configuration of plutonium by following aufbau principle is:
$P{u_{94}} = [Rn]5{f^6}7{s^2}$
In the outermost shell of plutonium also called valence shell that is $7s$ , there are two electrons present.
Hence, plutonium has two electrons in its valence shell.

Additional information:
Plutonium is the element with the highest atomic number to occur in nature. Trace quantities arise in natural $uranium - 238$ deposits when $uranium - 238$ captures neutrons emitted by decay of other $uranium - 238$ atoms. Plutonium is much more common on Earth as a product of neutron capture and beta decay, where some of the neutrons released by the fission process convert $uranium - 238$ nuclei into $plutonium - 239$ .

Note:
As we move from one element to another of the next higher atomic number, one proton and one electron are added each time to the neutral atom. The maximum number of electrons in any shell is $2{n^2}$ where $n$ is the principal quantum number. The maximum number of electrons in a subshell $(s,p,d,f)$ is equal to $2(2l + 1)$ where $l = 0,1,2,3...$ Thus these subshells can have a maximum of $2,6,10$ and $14$ electrons respectively.