In the periodic table, calcium (Ca) is in Group 2 and typically forms +2 cations. To achieve stability, calcium would typically bond with an atom that can provide two electrons or accept two electrons in a compound.
- Carbon (C) is in Group 14 and tends to form covalent bonds but may not effectively balance the +2 charge from calcium in a simple ionic compound.
- Bromine (Br) is in Group 17, which has a -1 charge and can bond with calcium to form the compound CaBrâ‚‚. This would balance the +2 charge from calcium with two -1 charges from two bromine atoms.
- Boron (B) is in Group 13 and primarily forms covalent bonds, but its properties do not lead to a stable ionic bond with Ca in a straightforward manner.
- Oxygen (O) is in Group 16 and typically forms a -2 charge, allowing the formation of a stable ionic compound CaO.
Given the context of stable ionic compounds, both bromine (Br) and oxygen (O) could form stable molecules with calcium (Ca). However, since the question asks for one atom that could represent X in the formula CaX, the best choices based on the typical bonding behavior would be bromine (Br) or oxygen (O). If I have to choose one based on common ionic bonding, I would go with:
bromine (Br)
It easily forms a stable compound with calcium as CaBrâ‚‚.