Schemes 38: Comparison of Cartier divisors and Pic

This lecture is part of an online algebraic geometry course on schemes, based on chapter II of "Algebraic geometry" by Hartshorne.
In this lecture we Define a homomorphism from Caritier divisor classes to the Picard group, and show that it is an isomorphism for integral schemes.
We use this to calculate the Picard group of affine space,
and use this in turn to calculate the Picard group of projective space.