Question

Using the periodic table, choose the more reactive non-metal.

Br or As
and
Br and At

Answer 1

Answer: The correct answer for 1 is Bromine and for 2 is Bromine.

Step-by-step explanation:

Reactivity of a non-metal is defined as the tendency of gaining electrons. It increases as we move across a period and decreases as we move down the group.

As, the size of an element increases, the valence electrons gets away from the nucleus and the tendency of an element to gain electrons decreases.

• For 1: Br or As

Bromine is present in Period 4 and Group 17 of the periodic table.

Electronic configuration of bromine =
`[Ar]3d^(10)4s^24p^5`

It can only accept 1 electron to attain stability.

Arsenic is present in Period 6 and Group 15 of the periodic table.

Electronic configuration of Arsenic =
`[Ar]3d^(10)4s^24p^3`

It will gain 3 electrons to attain stability.

Tendency of bromine to accept electron is more than the arsenic and moreover the size of bromine is small and will easily accept an electron.

Hence, bromine is more reactive non-metal.

• For 2: Br or At

Bromine is present in Period 4 and Group 17 of the periodic table.

Astatine is present in Period 6 and Group 17 of the periodic table.

Both the elements have to gain 1 electron but the size of bromine is less than the size of astatine. And therefore, the tendency of accepting an electron by bromine is more than the tendency of astatine.

Hence, bromine is more reactive non-metal.

Answer 2

The reactivity generally decreases on moving down the group

So out of Br and At , Bromine lies above At so Br will be more reactive than At

Out of Br and As, Bromine is more reactive as reactivity increases on moving from left to right in p-block