Which of the following best explains why alkali and alkaline earth metals tend to lose electrons easily?

• A. They have low ionization energies due to their valence electrons being far from the nucleus.
• B. Their atomic radii are very small, so electrons are tightly held.
• C. They have high electronegativities, which makes them attract electrons.
• D. They have completely filled valence shells, making them stable.

Answer: (A)

Verified step by step guidance

1. Understand that alkali metals (Group 1) and alkaline earth metals (Group 2) are elements that tend to form positive ions by losing electrons.
2. Recall that the ease of losing electrons is related to the ionization energy, which is the energy required to remove an electron from an atom.
3. Recognize that these metals have their valence electrons in outer shells that are relatively far from the nucleus, which reduces the electrostatic attraction between the nucleus and the valence electrons.
4. Because the valence electrons are less tightly held, the ionization energies of these metals are low, making it easier for them to lose electrons and form cations.
5. Evaluate the other options: small atomic radii would mean electrons are held tightly (which is not true here), high electronegativity means attracting electrons (not losing), and completely filled valence shells imply stability and less tendency to lose electrons, which does not apply to these metals.