Question

For each of the following pairs of ions, write the symbol for the formula of the compound they will form:

a) Na+ and Cl-
b) Ca²+ and Br-
c) Al³+ and O²-
d) K+ and F-

Answer 1

Chemical formulas for compounds are written based on the charge of the ions. Na+ and Cl- combine to form NaCl; Ca2+ and Br- form CaBr2; Al3+ and O2- form Al2O3; K+ and F- combine to form KF.

Step-by-step explanation:

To determine the chemical formula for a compound formed by ions, you need to use the charge of the ion to determine the ratio in which the ions will combine to form a neutral compound. Here are the compounds formed from the given ions:

• Na+ and Cl- will form NaCl (sodium chloride).
• Ca2+ and Br- will form CaBr2 (calcium bromide).
• Al3+ and O2- will form Al2O3 (aluminum oxide).
• K+ and F- will form KF (potassium fluoride).

Each of these compounds is neutral because the total positive charge equals the total negative charge. For example, in the case of calcium bromide, two bromide ions (each with a -1 charge) are needed to balance the +2 charge of the calcium ion.