How many valence electrons does Calcium have?
The correct answer and explanation is:
Calcium has 2 valence electrons.
To understand this, it’s important to know how the electron configuration of calcium works. Calcium (Ca) is an element in Group 2 of the periodic table, also known as the alkaline earth metals. These elements are characterized by having two electrons in their outermost electron shell.
The atomic number of calcium is 20, which means it has 20 electrons in total. Its electron configuration is:
1s22s22p63s23p64s21s^2 2s^2 2p^6 3s^2 3p^6 4s^2
The first two energy levels (1s, 2s, 2p, 3s, 3p) are fully occupied, and the outermost shell is the 4th energy level, where two electrons occupy the 4s orbital. These two electrons in the 4s orbital are the valence electrons of calcium.
Valence electrons are important because they determine how an atom interacts with other atoms during chemical reactions. Elements in the same group (like calcium and other alkaline earth metals) have similar chemical properties because they all have the same number of valence electrons. Calcium, with its two valence electrons, is typically inclined to lose these electrons to achieve a more stable electron configuration, like the noble gases. This is why calcium often forms +2 ions (Ca²⁺) in ionic compounds.
Thus, understanding the periodic table and electron configuration helps explain why calcium has two valence electrons and how it behaves in chemical reactions.