Question

How many 1s energy states are present in one mole of sodium vapour? Are they all filled in normal conditions? How many 3s energy states are present in one mole of sodium vapour? Are they all filled in normal conditions?

Answer 1

One mole of Sodium Vapour

Explanation:

• Atomic Number of Sodium is 11.

• The electronic configuration of sodium is  $1s^22s^2 2p^63s^1$.

• There are 11 electrons exist in one sodium atom.

• If N atoms exists in a sodium crystal then total number of electrons are 11 N.

• Two states in energy level 1s exists for each sodium atom so there will be 2 N states in energy level 1s for sodium crystal.Similarly, there will be 2 N states in energy level 3s.

Under normal conditions, 1s energy state is all filled and 3s energy state is half or partially filled.

Answer 2

The atomic number for sodium is 11. The sodium’s electronic configuration is 1s2 2s2 2p6 3s1.

Explanation:

• It is to be known that there will be 11 electrons in one sodium atom. So, consider that the sodium crystals have N atoms, so the electrons total will be 11 N.
• It is known that for each atom, in the energy level 1s, there are two states. So, there will be 2 N states for 1s energy level sodium crystals. Likewise, in 3s energy level, the total number of states will be 2 N.
• Under the normal conditions, 1s state is occupied. But there is only one electron per sodium atom in the 3s state, so there will be half-filled 3s band.