Question

What element is in period 4 and has 4 number shells and 3 valence electrons?

Can't find it anywhere

Answer 1

Gallium (Ga)

Explanation:

Gallium is in period 4 on the periodic table and has 31 electrons:

![chem4kids.com]()
`=>`The first shell is complete with 2 electrons

`=>`The second shell is complete with 8 electrons

`=>`The third shell is complete with 18 electrons

`=>`The fourth shell is left not fully complete, so the remaining 3 electrons are valence electrons in an atom of gallium metal .

Answer 2

Sc number 21 Scandium

Explanation:

Scandium atomic number 21 is in the fourth period.
The electron configuration of Scandium is
`1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^1`

Scandium has three different kinds of subshells
s, p and d .

Scandium has four different main electron shells
1st , 2st , 3rd and 4th .

Scandium has 3 valance electrons `4s^2 3d^1`

2 4s electrons
1 3d electron
for a total of 3 valance electrons.