Based on its electronic configuration an atom of manganese would have________unpaired electrons and would be expected to be________.

(a)3,paramagnetic
(b)2;diamagnetic
(c)0,diamagnetic
(d)5,paramagnetic

The configuration of Mn, atomic number 25 is

1s2 2p2 2p6 3s2 3p6 3d5 4s2. Except for Cu and Cr, the 3d elements have the number of electrons in the 3d shell that is the same as the second number of the atomic number. Thus, Mn has 5 electrons in the 3d shell. And Hund's rule of maximum multiplicity tells us that electrons are unpaired if possible. Therefore, all 5 electrons can be unpaired and that makes it paramagnetic.

To determine the number of unpaired electrons and the magnetic property of an atom based on its electronic configuration, we need to look at the electron configuration of manganese (Mn).

The electron configuration of manganese is 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁵.

To determine the number of unpaired electrons, we look at the last partially filled subshell, which in this case is the 3d subshell. The 3d subshell can hold a maximum of 10 electrons. Since there are 5 electrons in the 3d subshell, it means there are 5 unpaired electrons.

Now, to determine the magnetic property:
- If there are unpaired electrons, the atom is paramagnetic (meaning it is attracted to a magnetic field).
- If there are no unpaired electrons, the atom is diamagnetic (meaning it is not attracted to a magnetic field).

Since manganese has 5 unpaired electrons, the correct answer is (d) 5, paramagnetic.