How can atoms make up all of the substances around you ?

They all have different compositions of protons, neutrons, and electrons. This causes variety and makes atoms different so they can make up different substances

Because there are a lot of atoms in the substances

By water evaporation from the leaves is created a negative pressure at the top of the tree that promotes the ascension  of the water through channels that are called xylem. there are also two molecule forces that are involved: the intra-water molecules cohesion (water molecules stick to each other) and the adhesion when the water molecules stick to the channels they are running in. this is what enables water to go from the roots to the top of a tall tree.