Question

Element A and B have 3 and 6 electrons in their outermost shell, respectively.

a) Which element will gain electrons and how many, while forming a chemical compound? What will be the electrical charge on the ion of that element?

b) Which element will lose electrons and how many, while forming a chemical compound? What will be the electrical charge on the ion of that element?

Answer 1

Valence electrons-

• The number of electrons in the outermost shell of an atom.
• Example- Sodium has 1 electron in the outermost shell, aluminium has 3 electrons in the outermost shell.

Valency-

• The number of electrons donated or accepted by an atom when it forms a chemical compound.
• Example- Magnesium has 2 electrons in the outermost shell and to complete the outermost it will lose 2 electrons.
• hence its valency is 2.

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a)

• Element B has 6 electrons in the outermost shell.
• Its valency is 2.
• It will gain 2 electrons to complete its outermost shell.
• Element B will be charged negatively as it will gain 2 electrons

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b)

• Element A has 3 electrons in the outermost shell.
• Its valency is 3.
• It will lose 3 electrons to complete its outermost shell.
• Electron A will be charged positively as it will lose 3 electrons.