Campbell Biology chapter 2 | Questions and Answers with complete solution

matter - anything that has mass and takes up space element - any substance that cannot be broken down into simpler substances by chemical reactions. (92 elements are recognized, 25 are essentil for life) compound - consisting of two or more substances or ingredients or elements or parts combined in a fixed ratio. trace elements - Elements required by an organism in only minute quantities atom - the smallest component of an element having the chemical properties of the element neutrons - the particles of the nucleus that have no charge protons - positively charged particles electrons - negatively charged subatomic particles atomic nucleus - An atom's central core, containing protons and neutrons. atomic number - the number of protons in the nucleus of an atom, written as a subscript to the left of the symbol. mass number - the sum of the number of neutrons and protons in an atomic nucleus atomic mass - total mass of the protons and neutrons in an atom, measured in atomic mass units