HOW TO SOLVE:  Writing Orbital Diagram

QUESTION:

Write the orbital diagram for oxygen atom (O) and determine the number of unpaired electrons.

WORKED OUR SOLUTION & EXPLANATION:

Orbital diagrams are visual representations of electron configurations. Boxes are used for suborbitals and arrows are used to represent electrons. 

(a) in O (oxygen) there are 8 electrons in its neutral atom, given by the periodic table. The electron configuration for oxygen is 1s2 2s2 2p4.  For any "s" orbital, one box is written (because it has 1 sub-orbital); for "p" there are three boxes drawn, for 3 sub-orbitals. 

Now, let's detail the filling of these orbitals:

• 1s Orbital: The first two electrons fill the 1s orbital. This orbital is completely filled with two electrons, both of which are paired.

• 2s Orbital: The next two electrons fill the 2s orbital. This orbital is also completely filled with two electrons, which are paired.

• 2p Orbitals: The next four electrons go into the 2p orbitals. There are three 2p orbitals (2px, 2py, 2pz), each capable of holding two electrons. According to Hund's rule, the first three electrons will occupy separate orbitals (one in each), and the fourth will pair up with one of the earlier electrons.

The orbital diagram for oxygen is represented as follows:

This distribution of electron above indicates that oxygen has two unpaired electrons, both located in the 2p orbitals. Unpaired electrons are significant because they contribute to the chemical reactivity and magnetic properties of the atom.