How many numbers of electrons are there in the valence shell with atomic number 20?

The correct answer is: 2

• The atom with the atomic number 20 will have 20 electrons around the nucleus.
• The first shell possesses 2 electrons, the second shell holds 8, the third shell holds 8 and the last shell holds 2 electrons.
• The last shell or the outermost shell is the valence shell and the electrons are valence electrons.
• The atom that has atomic number 20 is Calcium and it has 2 valence electrons.