How many valence electrons must a calcium atom lose to get 8 valence electrons?
It must lose two electrons (the outside two "valence" electrons), then the next inner shell will have eight.
To determine the number of valence electrons that a calcium atom must lose to get 8 valence electrons, we need to know the electron configuration of calcium.
The atomic number of calcium is 20, which means it has 20 electrons. The electron configuration of calcium is 1s² 2s² 2p⁶ 3s² 3p⁶ 4s².
The valence electrons are the electrons in the outermost shell, which is the 4th shell (designated by the 4s orbital in the electron configuration).
Calcium has 2 valence electrons in its outermost shell. To achieve stability, it needs a full outer shell, which would be 8 valence electrons.
Since calcium needs to lose 2 electrons to reach the stable configuration of 8 valence electrons, it tends to form Ca²⁺ ions by losing its two valence electrons. This gives it a full outer shell and a more stable electron configuration.
So, a calcium atom must lose two valence electrons to reach a total of 8 valence electrons.