Question

1. write the formulas for the following compounds: (a) sodium iodide (b) beryllium fluoride (c) magnesium oxide (d) aluminum sulfide 4. name each of the compounds in question 3. 5. write the formulas for the following combinations of elements: (a) lithium and fluorine (b) calcium and bromine (c) cesium and nitrogen (d) aluminum and nitrogen

Explanation:

Step1: Determine ion charges

Sodium (Na) has a +1 charge and iodine (I) has a - 1 charge. For an ionic - compound to be neutral, the ratio of ions should be such that the total charge is zero. So, the formula for sodium iodide is $NaI$.

Step2: 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 every beryllium atom. So, the formula is $BeF_2$.

Step3: Determine ion charges for magnesium oxide

Magnesium (Mg) has a +2 charge and oxygen (O) has a - 2 charge. The ratio of Mg to O is 1:1, and the formula is $MgO$.

Step4: Determine ion charges for aluminum sulfide

Aluminum (Al) has a +3 charge and sulfur (S) has a - 2 charge. To balance the charges, we find the least - common multiple of 3 and 2, which is 6. So, we need 2 aluminum atoms and 3 sulfur atoms, and the formula is $Al_2S_3$.

Answer:

a. $NaI$
b. $BeF_2$
c. $MgO$
d. $Al_2S_3$