Final answer:
Lithium's electronic configuration is 1s2 2s1, and the bond order in a Li2 molecule is 1, indicating a stable single bond. The lithium atom is paramagnetic, but the Li2 molecule is diamagnetic.
Step-by-step explanation:
The electronic configuration of a lithium atom is 1s2 2s1. When two lithium atoms combine to form a lithium molecule (Li2), the valence electrons from each atom occupy the 2s bonding molecular orbital. There are two valence electrons in total, which means that the bond order for Li2 is 1, indicating a single bond.
The magnetic property of lithium can be determined by the presence of unpaired electrons. In the case of a lithium atom, there is one unpaired electron in the 2s orbital, rendering the atom paramagnetic.
However, in the case of Li2, both electrons pair up in the bonding orbital, so the molecule does not display magnetic properties and is diamagnetic.