Question

1. choose the best answer.

which of these element groups is most reactive, especially in water?
alkaline earth
alkali
noble gases
transition

1. choose the best answer.

_____ are the least reactive family of elements.
noble gases
halogens
alkaline earth metals
alkali metals

Explanation:

For question 17: Alkali metals (Group 1) have one valence electron, which they easily lose. When they react with water, they produce hydrogen gas and a metal hydroxide. For example, sodium (\(Na\)) reacts with water (\(H_2O\)) as \(2Na + 2H_2O=2NaOH + H_2\uparrow\). Alkaline - earth metals (Group 2) have two valence electrons and are less reactive than alkali metals. Noble gases have a full valence shell (usually 8 electrons, except for helium which has 2) and are inert. Transition metals generally have lower reactivity compared to alkali metals and their reactivity varies.
For question 18: Noble gases have a full valence electron shell (either 2 or 8 electrons). This stable electron configuration means they have little tendency to gain, lose, or share electrons. Halogens (Group 17) have 7 valence electrons and are very reactive as they want to gain one electron. Alkaline - earth metals (Group 2) have 2 valence electrons and are more reactive than noble gases. Alkali metals (Group 1) have 1 valence electron and are highly reactive.

Answer:

1. alkali
2. Noble gases