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

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Answer 1 · 2018-03-20T13:50:51

Gallium (Ga)

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

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#=>#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 · 2018-03-20T13:54:30

Sc number 21 Scandium

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.