Biology. Chapter 3 Section 1. Atoms. Smallest unit of matter that can not be broken down by chemical means. All matter is made up of atoms. Positively charges core surrounded by a negatively charged region. Atomic Structure. Atoms are made of three types of particles.
Chapter 3 Section 1
example: Each atom of the element carbon has 6 protons.
Atoms of an element can have different number of neutrons. These atoms are isotopes.