Chapter+2+Vocab


 * __2.1__**
 * Chlorophyll-**A molecule found in chloroplasts of plants that absorb light.
 * __2.2__**
 * Matter-** Anything that occupies space and has mass.
 * Chemical Element-** A substance that can't be broken down to other substances by chemical means; composes matter.
 * Trace Elements-** Elements that are necessary for life for only some organisms and usually in very small quantities.
 * __2.3__**
 * Compound-** A bond between two or more elements in a fixed ratio.
 * __2.4__**
 * Atom-** Smallest unit of matter that still has properites of an element.
 * Element-** Consists of atoms that are specific to that element. cannot be broken down into other substances by chemical means.
 * Proton-** Positively charged particle found in the nucleus of an atom.
 * Mass # (atomic mass)-** Sum of protons and neutrons in an atom's nucleus.
 * Isotope-** Variant form of an element; has same number of protons and electrons, but different number of neutrons.
 * Radioactive Isotope-** An isotope that is unstable, causing the nucleus to decay spontaneously; gives offparticles and energy.
 * __2.6__**
 * Electron Shell-** Energy levels at which electrons occur in atoms.
 * Chemical Bonds-** An attraction that holds two atoms together; usually when an atom completes another's valence electron shell.
 * __2.7__**
 * Ion-** An atom or molecule with an electrical charge caused by a gain or loss of electrons.
 * Ionic Bond-** Attraction that holds together two oppositely-charged ions
 * __2.8__**
 * Molecule-** Two or more atoms held together by covalent bonds.
 * Double Bond-** When two atoms share two pairs of electrons by covalent bonding.
 * __2.11__**
 * Cohesive-** The tendency of molecules of the same kind to stick together.
 * Adhesive-** The attraction between different kinds of molecules
 * Heat-** The total amount of energy associated with the movement of atoms and molecules in a body of matter.
 * Temperature-** The average speed of the molecules in a substance.
 * Heat Capacity-** The amount of heat energy that it takes to raise 1 gram of a substance 1 degree C.