Question

An element barium has atomic number 56. Look up its position in the periodic table and answer the following question.

1. Is it a metal or a non-metal?
2. Is it more or less reactive than calcium?
3. What is its valency?
4. What will be the formula of its phosphate?
5. is it larger or smaller than caesium (Cs) in size?

Answer 1

1. Since it belongs to group II, it has 2 valence electrons and hence it is a metal.
2. Barium is placed below calcium in the group. Since, it has more number of shells; it is easier for it to lose its valence electrons to complete its octet configuration. Hence it is more reactive than calcium.
3. It needs to lose its 2 valence electrons to complete its octet configuration; therefore its valency is also 2.
4. Ba₃[PO4]₂ (Barium Phosphate)
5. As we move from left to right in a period, the size decreases, therefore, it will be smaller than cesium.