What is an alkali metal with fewer than 10 protons in its nucleus?

            Lithium

Explanation:

                  Alkali metals are group of metals which are present in first group of periodic table. As we know atomic number is equal to number of protons contained by a particular element. Therefore, the alkali metals along with there number of protons are listed below;

Alkali Metal                                         Number of Protons

Lithium                                                               3

Sodium                                                             11

Potassium                                                         19

Rubidium                                                         37

Cesium                                                             55

Francium                                                          87

Hence, it is cleared from above table that Lithium is having fewer protons than 10.

Alkali metals are known as the elements that constitute the s-block of the periodic table. Some of the elements of alkali metals are lithium, sodium, caesium, and potassium. The alkali metal with fewer than 10 protons in the nucleus is Lithium.

The alkali metals are the elements in which the valence electrons are filled in the s-orbital of the element. The metals occupy the first group of the periodic table. The protons are the sub-atomic particles, which have positive charge and are embedded in the nucleus. The electrons are the negatively charged sub-atomic particles, which revolve around the nucleus. The element with the fewer than 10 protons in the nucleus is lithium.

Some of the number of protons in the alkali metals are listed below:

  Alkali Metal                                                       Protons

Therefore, the alkali metal lithium has 3 protons in its nucleus.

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