How many atoms of each element are needed to create an ionic compound of strontium selenide

Step 1:

Calculate the ionic charges on both atoms:

As Strontium belongs to Group-II in periodic table so it will tend to loose two electrons and form Sr⁺², i. e.

Sr → Sr⁺² + 2 e⁻

While, Se belonging to Group-VI will tend to gain two electrons and form Se⁻², i. e.

Se + 2 e⁻ → Se⁻²

Step 2:

Multiply the coefficient of each element by the charge of other element.

Se⁻² * 2 = 2 Se⁻² ∴ where 2 is charge on Sr

And,

Sr⁺² * 2 = 2 Sr⁺² ∴ where 2 is charge on Se

So, the formula comes out to be,

Sr₂Se₂

Or divide both coefficients by 2 to have a simplest form. i. e ...

SrSe

Result:

One One atoms of each element are needed to create an ionic compound of Strontium Selenide.