The main function is to help them see with all their eyes.
Only one atom because atom with 17 electrons need that one electron to become stable
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I thinks it's true but I'm not sure
The 4th energy level (row), 's' orbital block, 2nd group (column). The valence electrons are found in the highest energy level of the electron configuration in the 's' and 'p' orbitals. In the case of calcium this is 4s2 . This gives calcium an 's' orbital with a pair of electrons in its valence shell
