Strontium has an electron configuration of [Kr]5s²
Further explanation
In an atom there are levels of energy in the shell and sub shell
This energy level is expressed in the form of electron configurations.
Writing electron configurations starts from the lowest to the highest sub-shell energy level. There are 4 sub-shells in the shell of an atom, namely s, p, d and f. The maximum number of electrons for each sub shell is
s: 2 electrons
p: 6 electrons
d: 10 electrons and
f: 14 electrons
From an electron configuration of [Kr]5s² can be concluded :
- element is in period 5 (5 = shell)
- element is group 2(valence electron =2 and block s)
- has atomic number 38 (Kr = 36 + 2(valence elektron from 5s²)
If we look at the periodic system, the elements that meet the requirements in question are Strontium (Sr)