Question

1. write the formulas for the following compounds: (a) sodium iodide (b) beryllium fluoride (c) magnesium oxide (d) aluminum sulfide

Explanation:

Step1: Determine ion charges

Sodium (Na) has a +1 charge and iodine (I) has a - 1 charge. To form a neutral compound, the ratio is 1:1.

Step2: Write the formula

The formula for sodium iodide is $NaI$.

Step3: Determine ion charges for beryllium fluoride

Beryllium (Be) has a +2 charge and fluorine (F) has a -1 charge. To balance the charges, we need 2 fluorine atoms for 1 beryllium atom.

Step4: Write the formula

The formula for beryllium fluoride is $BeF_2$.

Step5: Determine ion charges for magnesium oxide

Magnesium (Mg) has a +2 charge and oxygen (O) has a -2 charge. The ratio for a neutral compound is 1:1.

Step6: Write the formula

The formula for magnesium oxide is $MgO$.

Step7: Determine ion charges for aluminum sulfide

Aluminum (Al) has a +3 charge and sulfur (S) has a -2 charge. The least - common multiple of 3 and 2 is 6. So we need 2 aluminum atoms (+6 total charge) and 3 sulfur atoms (-6 total charge).

Step8: Write the formula

The formula for aluminum sulfide is $Al_2S_3$.

Answer:

(a) $NaI$
(b) $BeF_2$
(c) $MgO$
(d) $Al_2S_3$