Which noble gas is located in period 3 of the periodic table?

• A. Helium (He)
• B. Krypton (Kr)
• C. Neon (Ne)
• D. Argon (Ar)

Answer: (D)

Verified step by step guidance

1. Understand that the periodic table is arranged in periods (rows) and groups (columns), where each period corresponds to the principal energy level of the valence electrons.
2. Identify that period 3 refers to the third row of the periodic table, which includes elements with electrons filling the third energy level.
3. Recall that noble gases are elements in Group 18, characterized by having a full valence shell, making them chemically inert.
4. List the noble gases in order by period: Helium (He) in period 1, Neon (Ne) in period 2, Argon (Ar) in period 3, Krypton (Kr) in period 4, and so on.
5. Conclude that the noble gas located in period 3 is Argon (Ar), as it is the noble gas that completes the third energy level.