Living in the Environment 16th Ed. : Ch.2 Key Terms

Chapter 2 Key Terms acidity Ions are also important for measuring a substance?s acidity in a water solution, a chemical characteristic that helps determine how a substance dissolved in water will interact with and affect its environment. atom The most basic building block of matter is an atom: the smallest unit of matter into which an element can be divided and still retain its chemical properties. atomic number Each element has a unique atomic number, equal to the number of protons in the nucleus of its atom. atomic theory The idea that all elements are made up of atoms is called the atomic theory and is the most widely accepted scientific theory in chemistry. cells