It depends on the atom.
Atoms may have up to three energy levels, or layers of electrons, although some elements, such as helium, have only one. If an atom has one energy level, its valence electrons may total up to only two. If it has two or three energy levels, It may have up to eight total valence electrons. An atom is neutral when it has the greatest possible number of electrons.
Two valence electrons
That neutral silicon atom has four electrons in its valence shell.
as many protons as they have.
Potassium atom has 1 valence electron
3
A neutral atom of fluorine contains 7 valence electrons.
A neutral atom of oxygen would have 6 valence electrons.
A neutral atom of silicon will have 4 valence electrons. The amount of valence electrons that a neutral atom will have can be found by the atoms group number in the periodic table.
Two valence electrons
Aluminum has 3 valence electrons.
Aluminum has 3 valence electrons.
That neutral silicon atom has four electrons in its valence shell.
6
as many protons as they have.
A neutral oxygen atom has six valence electrons.
Potassium atom has 1 valence electron
There are two non-valence electrons in a neturol boron atom. The electronic configuration of neutral boron is 1s2, 2s2 2p1. The three electrons in the 2d shell are the valence electrons; the non--valence electrons are in the 1s orbital.