When electrons are removed from the outermost shell of a calcium atom, the atom becomes:

• A. a Ca^{2-} ion
• B. a Ca^{2+} ion
• C. a neutral calcium atom
• D. a Ca^{+} ion

Answer: (B)

Verified step by step guidance

1. Recall that a neutral calcium atom has an equal number of protons and electrons. Calcium's atomic number is 20, so it has 20 protons and 20 electrons in its neutral state.
2. Understand that when electrons are removed from an atom, the number of electrons decreases while the number of protons remains the same, resulting in a positively charged ion (cation).
3. Recognize that the outermost shell of calcium contains 2 electrons in the 4s subshell, which are the electrons typically lost during ion formation.
4. When calcium loses these 2 outermost electrons, it forms a Ca^{2+} ion because it now has 2 more protons than electrons, giving it a +2 charge.
5. Therefore, the correct description of a calcium atom after losing electrons from its outermost shell is a Ca^{2+} ion.