Question
The atomic number of an element is $20.$ Write its electronic configuration. State whether this element is a metal or a non$-$metal. What is its valency? Write the name and formula of the compound which this element forms with chlorine.
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Answer
The element with an atomic number of $20$ is calcium $($Ca$)$.
The electronic configuration of calcium is $: 1s^2 \ 2s^2 \ 2p^6 \ 3s^2 \ 3p^6 \ 4s^2.$
Calcium is a metal because it is located in Group $2\ ($or Group $\text{IIA})$ of the periodic table$,$ which consists of metals known as alkaline earth metals.
The valency of calcium is $+2.$
The compound that calcium forms with chlorine is calcium chloride. The chemical formula for calcium chloride is $CaCl_2.$
The electronic configuration of calcium is $: 1s^2 \ 2s^2 \ 2p^6 \ 3s^2 \ 3p^6 \ 4s^2.$
Calcium is a metal because it is located in Group $2\ ($or Group $\text{IIA})$ of the periodic table$,$ which consists of metals known as alkaline earth metals.
The valency of calcium is $+2.$
The compound that calcium forms with chlorine is calcium chloride. The chemical formula for calcium chloride is $CaCl_2.$
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