Download Ion- an atom or molecule with a net electric charge due to the loss or

Chemistry: Unit Two
Chapter Five Vocabulary
Nathan Meadows
Element- Each of more than one hundred substances that cannot be chemically interconnected or broken down into
simpler substances and are primary constituents of matter. Each element is distinguished by its atomic number, i.e., the
number of protons in the nuclei of its atoms.
Law of Conservation of Mass- Matter cannot be created or destroyed in an isolated system
Law of Definite Proportions- law stating that every pure substance always contains the same elements combined in the
same proportions by weight
Cathode ray- A beam of electrons emitted from the cathode of a high-vacuum tube.
Electron- A stable subatomic particle with a charge of negative electricity, found in all atoms and acting as the primary
carrier of electricity in solids.
Phosphorescence- Emitting light without appreciable heat as by slow oxidation of phosphorous; "the phosphorescent
glow of decaying wood"
X-ray- Electromagnetic radiation of high energy and very short wavelength (between ultraviolet light and gamma rays)
that is able to pass through many materials opaque to light.
Radioactivity- The emission of ionizing radiation or particles caused by the spontaneous disintegration of atomic
nuclei.
Nuclear radiation- The process by which an unstable atomic nucleus loses energy by emitting ionizing particles or
radiation. The emission is spontaneous in that the nucleus decays without collision with another particle.
Electromagnetic radiation- Kind of radiation including visible light, radio waves, gamma rays, and X-rays, in which
electric and magnetic fields vary simultaneously.
Wavelength- The distance between successive crests of a wave, esp. points in a sound wave or electromagnetic wave.
Frequency- The rate at which a vibration occurs that constitutes a wave, either in a material (as in sound waves), or in
an electromagnetic field (as in radio waves and light), usually measured per second.
Ground State- The lowest energy state of an atom or other particle.
Excited electron- An electron in an atom that has absorbed some energy, which has put it into a higher energy state. An
excited electron will usually decay back to its resting level and release of a packet of energy (a photon).
Spectroscopy- The branch of science concerned with the investigation and measurement of spectra produced when
matter interacts with or emits electromagnetic radiation.
Uncertainty principle- The principle that the momentum and position of a particle cannot both be precisely determined
at the same time.
Orbital- Each of the actual or potential patterns of electron density that may be formed in an atom or molecule by one
or more electrons and that can be represented as a wave function.
Atomic number- The number of protons in the nucleus of an atom, which determines the chemical properties of an
element and its place in the periodic table.
Mass number- The total number of protons and neutrons in a nucleus.
Atomic mass- The mass of an atom of a chemical element expressed in atomic mass units. It is approximately
equivalent to the number of protons and neutrons in the atom (the mass number) or to the average number allowing for
the relative abundances of different isotopes.
Isotopes- Each of two or more forms of the same element that contain equal numbers of protons but different numbers
of neutrons in their nuclei, so they differ in relative atomic mass but not in chemical properties.
Ion- an atom or molecule with a net electric charge due to the loss or gain of one or more electrons