Question

Sea salt contains calcium chloride (CaCl2), an ionic compound similar to table salt. One atom of calcium ( atomic number 20) bonds to two atoms of chlorine ( atomic number 17). Fill in the number of protons and electrons in each ion.
Chloride ion
Calcium ion
Chloride ion

Answer 1

To do this, first realise that the atomic number is the number of protons in the nucleus, so it's 17 for Chlorine, 20 for calcium. The ions will have different numbers of electrons -Ca forms a 2+ whereas chloride is 1-, so you can decide how many electrons each atom will have from the atomic number then adding or taking away until you get the right charge.