Question

which statement correctly compares an atom of an alkali metal with an atom of the alkaline earth metal next to it on the periodic table?
the alkali metal atom forms a +1 ion, while the alkaline earth metal atom forms a +2 ion.
the alkali metal atom forms a -2 ion, while the alkaline earth metal atom forms a +1 ion.
the alkali metal atom has one less shell of electrons than the atom of the alkaline earth metal.
the alkali metal atom has one more shell of electrons than the atom of the alkaline earth metal.

Explanation:

1. Recall the properties of alkali metals (Group 1) and alkaline earth metals (Group 2):

• Alkali metals have 1 valence electron, so they lose 1 electron to form \(+1\) ions.
• Alkaline earth metals have 2 valence electrons, so they lose 2 electrons to form \(+2\) ions.
• Regarding electron shells: Alkali and alkaline earth metals in the same period (next to each other on the periodic table) have the same number of electron shells. For example, Li (alkali, Period 2) and Be (alkaline earth, Period 2) both have 2 electron shells.

1. Analyze each option:

• Option 1: Alkali metals form \(+1\) ions (lose 1 valence electron), alkaline earth metals form \(+2\) ions (lose 2 valence electrons). This matches their electron configurations.
• Option 2: Alkali metals don't form \(-2\) ions, and alkaline earth metals don't form \(+1\) ions. This is incorrect.
• Option 3: Same - period alkali and alkaline earth metals have the same number of electron shells. So alkali metals don't have one less shell. Incorrect.
• Option 4: Same - period alkali and alkaline earth metals have the same number of electron shells. So alkali metals don't have one more shell. Incorrect.

Answer:

The alkali metal atom forms a +1 ion, while the alkaline earth metal atom forms a +2 ion.