StellarFormulas and Basics
Ionic compounds are compounds composed of two or more atoms that give or take electrons from each other forming themselves into ions. For example, table salt, NaCl, is composed of sodium and chlorine. As we learned in Unit 2, sodium is an alkali metal so it gives up one electron to form a cation with a +1 charge. Chlorine is a halogen so it needs one electron to have a full outer shell becoming an anion with a -1 charge. When these elements react, Na gives one electron to Cl. Both atoms become ions and are held together by the electrostatic attraction (positive and negative charges). (note - the cation always goes first)