Models in science help you get the idea of what something looks like that's why your teacher may ask you to draw a diagram to help you remember what the object looks like.
Hope this helps.
The answer is 2 electrons.
The electron configuration of calcium is 2:8:8:2
Calcium has two electrons in its outermost shell. These are its valence electrons and are the ones used in bonding with other elements. Valence electrons of an atom are those electrons that are in its outer energy shell or that are available for bonding.
Calcium is a metal. When metals react with non-metals, electrons are transferred from the metal atoms to the non-metal atoms forming ions. The resulting compound is known as an ionic compound.
For example, when calcium metal reacts with chlorine gas, calcium gives up its two valence electrons and Chlorine accepts them resulting in a new substance called calcium chloride in which the two elements have ended up forming ionic bonds.
Answer is: lithium is the least reactive and potassium is the most reactive of the three alkali elements.
<span>The </span>reactivity<span> of the alkali metals increases down the group because one valence electron (I group of Periodic system of elements) is farther away from nucleus and attraction force between electron and proton is weaker.</span>
