Campbell Biology chapter 2 Test Questions and Correct Answers.

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