Answer:
sodium, magnesium, aluminium, silicon, phosphorus, sulfur, chlorine, and argon.
Step-by-step explanation:
The third period contains eight elements: sodium, magnesium, aluminium, silicon, phosphorus, sulfur, chlorine, and argon. The first two, sodium and magnesium, are members of the s-block of the periodic table, while the others are members of the p-block.