To determine the correct chemical formula for calcium chloride, let's consider the valences of the elements involved:
1. Calcium (Ca) is in Group 2 of the periodic table, which means it has a valence of +2.
2. Chlorine (Cl) is in Group 17 of the periodic table, which means it has a valence of -1.
When calcium (Ca) bonds with chlorine (Cl) to form calcium chloride:
- One calcium atom, with a +2 charge, needs to be balanced by two chloride ions, each with a -1 charge.
- The formula thus needs to reflect that two Cl atoms are required to balance out the charge of one Ca atom.
Therefore, the correct chemical formula is [tex]\( CaCl_2 \)[/tex].
Thus, the correct answer is:
D. [tex]\( CaCl_2 \)[/tex]
