What is the order of elements in the periodic table based on?

• The number of protons in the nucleus
• The electric charge of the nucleus
• The number of neutrons in the nucleus
• Atomic mass

Elements that share properties of both metals and nonmetals are called metalloids.

What is the main reason that Group 17 elements, the halogens, are highly reactive?

• They have very small atomic masses.
• They readily lose electrons.
• They gain an electron to form a negative ion.
• They are already stable.

Which side of the periodic table are nonmetals like carbon found?

• Left-most side
• Right side
• Middle column
• Bottom rows