Question
Find the period in which these elements can be placed.
$_4Be,\ _{17}Cl,\ _2He,\ _{13}Al$
$_4Be,\ _{17}Cl,\ _2He,\ _{13}Al$
✓
Answer
- $_4Be-$ Electronic configuration is $(2, 2)$. It is placed in period $2.$
- $_{17}Cl-$ Electronic configuration is $(2, 8, 7)$. It is placed in period $3.$
- $_2He-$ Electronic configuration is $(2)$. It is placed in period $1.$
- $_{13}Al-$ Electronic configuration is $(2, 8, 3)$. It is placed in period $3.$
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