How many valence electrons does $Ra$ have?

Hint The basic concept of the general chemistry part which tells us about the valence electrons are nothing but defined as the electrons that are present in the outermost shell of an atom and this concept gives the correct answer.

Complete step – by – step answer:
In the lower classes of inorganic chemistry, we have studied the basic concepts of the chemistry that deals with the atoms and its electronic configuration and also the valence electrons in an atom.
Let us now see in detail about those concepts so that we will be able to solve this question.
- Atoms are composed of central nuclei in which the positively charged protons and the neutral species called the neutrons are concentrated together.
- Around this nucleus in an orbit, the negatively charged particles called the electrons revolve in the circular path.
Thus, these electrons are present in different numbers based on the atomic number and also each shell has a particular number of electrons in it.
- In the given atom radium that has the atomic symbol $Ra$ has the atomic number 88 and therefore, the electronic configuration of this element is given by, $[Rn]7{{s}^{2}}$

Therefore, this element has a total of 88 protons where the outermost shell has 2 electrons in it and thus the valence electrons of radium is 2.

Note: Note that for the elements that are having the greater atomic number , the electronic configuration is written in terms of the shorthand notations where the configuration represents the valence electrons which is preceded by the respective remaining electronic configuration possessing noble gas symbol in parenthesis.