Question

How many valence electrons are in an atom of strontium (Sr)? Consult the periodic table. A. 5 B. 2 C. 47.90 D. 22

Answer 1

Answer:

The option B is correct.

Strontium has 2 valence electrons.

Explanation:

• Since strontium (Sr) is in Group 2 it will have 2 valence electrons.

Answer 2

The smallest and the basic particle of a chemical element is said to be an atom. It is made up of three subatomic particles that is electrons, protons and neutrons.  The neutrons and protons are present in the nucleus of an atom whereas electrons are present in the orbits around the nucleus of the atom.  There are several shells in the orbital depending on the atomic number.  The electrons which are present in the outermost shell are said to be valence electrons.

They can be determined by the electronic configuration of the element.

The atomic number of strontium, $Sr$ is 38. The electronic configuration of strontium, $Sr$ is:

$1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}$

From the electronic configuration it is clear that the outermost shell of strontium, $Sr$ is $5s$. So, the number of valence electrons in strontium, $Sr$ is 2.

Hence, there are 2 valence electrons in an atom of strontium ($Sr$).