Question

Which group on the periodic table are the last reactive? A alkali metals B alkaline earth metals C halogens D noble gases

Answer 1

Answer:

D. Noble gases

Explanation:

• Noble gases are elements in the last group of the periodic table.

Why are they the least reactive elements?

• Noble gases have an octet configuration, which means they have maximum number of electrons in their outermost energy levels.
• This makes them stable, which means they are inert.
• Examples of noble gases include neon, argon, krypton, etc.

What is the Trend in reactivity in the periodic table?

Down the group from top to bottom

• The reactivity of metals in the periodic table increases down the group due the increase in the number of energy levels which makes it easier for them to lose electron(s).
• Non-metals react by gaining electron(s), therefore, their reactivity decreases down the group because as the energy level increases the nuclear charge decreases.

Across the period from left to right.

• Reactivity of metals decreases across the period because of an increase in nuclear charge which makes it more difficult for them to lose electron(s).
• On the other hand, reactivity of non-metals increases across the period due to increased nuclear charge that makes it easier for them to gain electron(s).