Glossary to the Periodic Table of Elements

Actinides. A series of chemical elements in the periodic table ranging in atomic number from 89 (actinium) to 103 (lawrencium), all of which are radioactive. Many are man-made.1
Alkaline earth metal. Any element in group 2 of the periodic table -- beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).1
Alkali metal. The following elements in group 1 of the periodic table: lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr).1
Allotrope. Two or more forms of the same element that have different chemical and/or physical properties.2
Alloy. A metal composed of two or more elements.1
Aloft. Flying.2
Alpha particle. The nucleus of a helium atom.3
Alternating current (AC). Electric current in which the electron flow changes direction many times a second. Alternating current is what powers most homes and businesses.4
Amalgam. A metal alloy containing the element mercury.1
Antibiotic. A drug doctors prescribe to treat bacterial infections.5
Atom. The basic particle of a chemical element.4
Atomic number. The number of protons inside the nucleus of an atom.4
Beta decay. The radioactive decay of an element in which an electron or positron is given off.1/6
Carbohydrates. Organic compounds that include sugars, starches, celluloses, and gums that are used as energy sources by the body.1/6/7
Carcinogen. A cancer-causing substance.
Catalyst. A substance that helps promote a chemical reaction.2
Combustible. Capable of burning.
Composite. A superior material created by combining two or more separate substances that maintain their original characteristics.1/2
Compound. A substance composed of two or more elements chemically bound together.
Condensation. The process by which a gas converts to a liquid.4
Corrosion. The wearing away of the surface of a substance (usually a metal) due to a chemical reaction.
Crucible. A container composed of materials that are highly resistant to heat and corrosion, often used by scientists to conduct chemical experiments.
Crystalline. Composed of crystals.
Cyclotron. A device that accelerates charged atomic particles to speeds approaching the speed of light.1
Direct Current (DC). Electric current in which electrons flow in only one direction. Flashlight batteries generate direct current.4
Distillation. The process of separating a liquid mixture by boiling it, then collecting and condensing the resulting vapors.1
DNA. Or deoxyribonucleic acid. A complex chemical compound found in all living cells. It’s what makes up our genes, which carry the genetic code that determines how our bodies develop.1
Ductility. A metal’s ability to be drawn into wire without breaking.
Electrolysis. The process by which dissolved metals are separated and collected by passing an electric current through the solution containing them.
Extrude. To force a material, such as metal or plastic through a die or very small holes to give it a certain shape.12
Fiber optics. A communications technology in which data, in the form of light pulses, is transmitted through thin, glass fibers.1
Filament. A thin electrical conductor, usually a metal wire, which is heated by the transmission of electrical current to produce light.2
Fuel cell. A device that converts a chemical fuel (often hydrogen) into electricity.1
Galvanize. The process of coating a metal, usually with zinc, to protect it from corrosion.
Gamma ray. Extremely high-energy radiation, similar to X-rays, but much higher in energy and with a shorter wavelength.8
Global warming. An increase in the earth’s average surface temperatures due to heat-trapping greenhouse gases produced from the burning of fossil fuels.1
Greenhouse gas. Air pollutants, like carbon dioxide, produced from the burning of fossil fuels, which trap heat in earth’s atmosphere and contribute to global warming.
Half-life. The time it takes for a radioactive isotope to lose one half of its potency.1
Henri Becquerel. French physicist who discovered radioactivity.1
Inert. Having a limited ability to react chemically with other substances.
Infrared radiation. A type of radiation invisible to the naked eye that falls between the visible light and microwave regions of the electromagnetic spectrum.1
Inorganic. Not composed of plant or animal matter.2
Insecticide. A chemical substance used to kill insects.
Ion. A positively or negatively charged atom or group of atoms.1
Ionize. The process by which an atom or group of atoms becomes positively or negatively charged due to the gain or loss of electrons.
Isotope. Atoms of an element with the same atomic number but different atomic masses and distinct physical properties.1
Lanthanides. A series of chemical elements in the periodic table ranging in atomic number from 57 (lanthanum) to 71 (lutetium), all of which share similar properties.
LED. Or light emitting diode. A semiconductor (often made of gallium, aluminum and arsenic, among other elements) that produces light when electricity is passed through it.6
Linear accelerator. A device in which subatomic particles are accelerated in a straight line to produce radiation, sometimes X-rays.6
Malleability. The ability of a metal to be worked into varying shapes.2
Marie Curie. Polish-born French physicist and two-time Nobel Prize winner best known, along with fellow physicist and husband Pierre Curie, for her discovery of several radioactive elements.1
Metal. A substance with the ability to conduct heat and electricity that is also ductile, malleable and highly reflective.1
Metalloid. A chemical element that falls between the metals and non-metals in the periodic table.1
Methanol. A flammable liquid alcohol often used as a solvent, a fuel or a fuel additive.1
Molecule. A group of atoms bound together in a definite arrangement.4
NASA. Or National Aeronautics and Space Administration. Government agency established in 1958 for the exploration of space.1
Neutron. A subatomic particle with no electric charge that resides in an atom’s nucleus.1
Noble gas. Any of the elements in the right-most column of the periodic table, including helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn).
Nuclear accelerator. A device that accelerates electrically charged atomic or subatomic particles and collides them with targets to produce high-energy radiation.1/6
Nuclear battery. A device that produces electricity by capturing electrons from a radioactive material.9
Nuclear chain reaction. The process by which a uranium atom splits, or fissions, and collides with other uranium atoms causing them to split as well, generating intense heat.
Nuclear control rods. Devices made of neutron-absorbing materials used to control the nuclear chain reaction in a nuclear reactor.
Nuclear fission. The splitting of an atom’s nucleus, resulting in a high amount of energy.1
Ore. A mineral deposit containing a valuable constituent, like iron, that can be mined.2
Organic. Composed of plant or animal matter.2
Oxidation. A chemical process by which an element’s atoms lose electrons, commonly by combining with oxygen.6
Oxide. A chemical compound composed of oxygen and another element.2
Ozone layer. A region in Earth’s upper atmosphere composed of high concentrations of ozone which filter out the sun’s harmful ultraviolet radiation.1
Pacemaker. An electronic device implanted in the chest to help steady the heartbeat.2
Paramagnetic. The characteristic of a material to be weakly attracted to a strong magnet.1
Periodic table. A matrix of the chemical elements arranged in order of increasing atomic weight.1
Phosphor. A material that luminesces when excited by electrons. Often used in television picture tubes.2
Photosynthesis. The process by which the chlorophyll in the leaves of green plants converts sunlight into energy.1
Pierre Curie. French physical chemist and husband of physicist Marie Curie. Co-winner of the Nobel Prize for physics in 1903. He and Marie Curie are credited with having discovered the radioactive elements radium and polonium.1
Pigment. A substance that adds color to other materials, often paint.
Platinum group. Six metallic elements in groups 8, 9 and 10 of the periodic table which share similar chemical and physical properties. They include ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), and platinum (Pt). 10<
Radioactivity. The tendency of some elements to spontaneously emit subatomic particles or radiation as their nuclei decay.2
Rare earth elements. Thirty elements in group 3 of the periodic table that compose the lanthanide and actinide series of elements.11
Refractive index. A measure of the bending of a beam of light as it passes through a medium such as glass.6
Rodenticide. A chemical substance used to kill rodents.
Salts. A substance that results from the chemical reaction between an acid and a base. Common table salt is one example of a salt.1
Semiconductor. A controllable conductor of electricity. The element silicon is an example of a semiconductor.
Silicate. A large group of minerals containing primarily the elements silicon and oxygen. Often used in the manufacture of glass and cement.1/2
Smelting. The process of separating a metal from its ores.1
Solder. A metal alloy with a low melting point used to join metal surfaces like pipes and electronic components.1
Steel. A metal alloy composed primarily of carbon and iron, usually incorporating other elements as well.1
Sublimation. The changing of a solid to a vapor without it passing through the liquid phase.1/6
Superoxide. A negatively charged (anion) oxygen molecule. 10<
Synthesize. To create something from individual parts.2
Tarnish. The tendency to become discolored due to exposure to air. Usually applies to metals.6
Telluride. Any chemical compound that includes the element tellurium as one of its components. 10<
Toxic. Poisonous.
Transactinide. The man-made elements following the actinide series in the periodic table with an atomic number greater than 103. 10<
Transition element. Any of the elements in groups 3 to 12 in the periodic table.
Transition metal. See transition element.
Ultraviolet radiation. Often referred to as UV rays. A form of radiation produced by the sun that extends from violet to X-rays within the electromagnetic spectrum.1
Wolframite. Chief ore of tungsten, commonly associated with tin ore in and around granite. Such occurrences include Cornwall, England; Northwestern Spain; Northern Portugal; Eastern Germany; and Myanmar, the former Burma.1


  3. A Guide to the Elements, Second Edition, Albert Stwertka.
  4. Science Encyclopedia.
  12. Webster’s New World Clilege Dictionary