what is the charge of magnesium
tht means the max no. of electrons in the first shell is 2. the max no. of electrons in the second shell is 8. and the max number of electrons in the third shell is 8....it goes on as the no. of electron in the atom increases. so the electron configuration for magnesium is 2.8.2. this shows tht the first and second shells are filled to the max. the third shell isn't. it has a 2+ charge because it has lost 2 electrons( which carries a negative charge), hence the atom is more positive than normal.