Answer to Question #60508 in Chemistry for Tim

Question

Why is there a drop in value from Nitrogen to Oxygen in period and why is there a drop in value from Phosphorus to Sulfur in period 3

Answer 1

While moving along the periods of periodic table, the properties of elements are changing.
In the 2nd period Oxygen has one more electron on the other shell comparatively to Nitrogen the same as Sulfur has one more electron comparatively to Phosphorus in the 3rd period). This influences the charge, atom’s diameter and mass, and, consequently, properties.