1.10.2 Spinning electrons
Electrons can be pictured as spinning in two directions (clockwise and anticlockwise), and when an atomic orbital contains its maximum complement of two electrons, those two electrons must always have opposite spins (one clockwise and the other anticlockwise).
This is depicted in Figure 9.
Strictly speaking this is not an accurate description, remember quantum mechanics tells you electrons are not found at specific points in space and must be described in terms of probability.
So they are not the spinning balls of charge shown here. However this representation does provide a useful model of how electrons occupy orbitals, and you will be using this in the next section.