atom: The basic unit of a chemical element. Atoms are made up of a dense nucleus that contains positively charged protons and uncharged neutrons. The nucleus is orbited by a cloud of negatively charged electrons.
battery: A device that can convert chemical energy into electrical energy.
bond: (in chemistry) A semi-permanent attachment between atoms — or groups of atoms — in a molecule. It’s formed by an attractive force between the participating atoms. Once bonded, the atoms will work as a unit. To separate the component atoms, energy must be supplied to the molecule as heat or some other type of radiation.
cell: (in biology) The smallest structural and functional unit of an organism. Typically too small to see with the unaided eye, it consists of a watery fluid surrounded by a membrane or wall. Depending on their size, animals are made of anywhere from thousands to trillions of cells. Most organisms, such as yeasts, molds, bacteria and some algae, are composed of only one cell.
chemical: A substance formed from two or more atoms that unite (bond) in a fixed proportion and structure. For example, water is a chemical made when two hydrogen atoms bond to one oxygen atom. Its chemical formula is H2O. Chemical also can be an adjective to describe properties of materials that are the result of various reactions between different compounds.
conservation: (v. conserve) The act of preserving or protecting something. The focus of this work can range from art objects to endangered species and other aspects of the natural environment.
electricity: A flow of charge, usually from the movement of negatively charged particles, called electrons.
electron: A negatively charged particle, usually found orbiting the outer regions of an atom; also, the carrier of electricity within solids.
element: A building block of some larger structure. (in chemistry) Each of more than one hundred substances for which the smallest unit of each is a single atom. Examples include hydrogen, oxygen, carbon, lithium and uranium.
ember: A glowing fragment left over from (or shot out by) a fire. It continues to smolder and burn, usually with no flame. The term usually refers to some hot leftover from a dying fire. An ember can ignite a new fire, however, if it makes contact with combustible materials.
fat: A natural oily or greasy substance occurring in plants and in animal bodies, especially when deposited as a layer under the skin or around certain organs. Fat’s primary role is as an energy reserve. Fat also is a vital nutrient, though it can be harmful if consumed in excessive amounts.
fire: The burning of some fuel, creating a flame that releases light and heat. (in neuroscience) The activation of a nerve or neural pathway.
force: Some outside influence that can change the motion of an object, hold objects close to one another, or produce motion or stress in a stationary object.
fossil fuel: Any fuel — such as coal, petroleum (crude oil) or natural gas — that has developed within the Earth over millions of years from the decayed remains of bacteria, plants or animals.
fuel: Any material that will release energy during a controlled chemical or nuclear reaction. Fossil fuels (coal, natural gas and petroleum) are a common type that liberate their energy through chemical reactions that take place when heated (usually to the point of burning).
fusion: (v. to fuse) The merging of two things to form a new combined entity. (in physics) The process of forcing together the nuclei of atoms. This nuclear fusion is the phenomenon that powers the sun and most other stars, producing heat and forging the creation of new, heavier elements.
gravity: The force that attracts anything with mass, or bulk, toward any other thing with mass. The more mass that something has, the greater its gravity.
green: (in chemistry and environmental science) An adjective to describe products and processes that will pose little or no harm to living things or the environment.
helium: An inert gas that is the lightest member of the noble gas series. Helium can become a solid at -272 degrees Celsius (-458 degrees Fahrenheit).
hydrogen: The lightest element in the universe. As a gas, it is colorless, odorless and highly flammable. It’s an integral part of many fuels, fats and chemicals that make up living tissues. It’s made of a single proton (which serves as its nucleus) orbited by a single electron.
inert: Inactive or having no chemical or physical effects.
kinetic energy: The energy held by an object due to its being in motion. The amount of this energy contained will depend on both the mass (usually weight) of the object and its speed.
mechanical: Having to do with the devices that move, including tools, engines and other machines (even, potentially, living machines); or something caused by the physical movement of another thing.
muscle: A type of tissue used to produce movement by contracting its cells, known as muscle fibers. Muscle is rich in protein, which is why predatory species seek prey containing lots of this tissue.
physics: The scientific study of the nature and properties of matter and energy. Classical physics is an explanation of the nature and properties of matter and energy that relies on descriptions such as Newton’s laws of motion. Quantum physics, a field of study that emerged later, is a more accurate way of explaining the motions and behavior of matter. A scientist who works in such areas is known as a physicist.
potential energy: The energy held by an object due not to its motion but instead to its position or condition (such as being held motionless by a brake or suspended from a wire). Examples of objects possessing this type of energy include a compressed spring or a mass of snow on a hillside (think of its capacity to create an avalanche).
power plant: An industrial facility for generating electricity.
radiate: (in physics) To emit energy in the form of waves.
radioactive: An adjective that describes unstable elements, such as certain forms (isotopes) of uranium and plutonium. Such elements are said to be unstable because their nucleus sheds energy that is carried away by photons and/or one or more subatomic particles. This emission of energy is by a process known as radioactive decay.
renewable energy: Energy from a source that is not depleted by use, such as hydropower (water), wind power or solar power.
solar: Having to do with the sun or the radiation it emits. It comes from sol, Latin for sun.
solid: Firm and stable in shape; not liquid or gaseous.
sound wave: A wave that transmits sound. Sound waves have alternating swaths of high and low pressure.
star: The basic building block from which galaxies are made. Stars develop when gravity compacts clouds of gas. When they become hot enough, stars will emit light and other forms of electromagnetic radiation. The sun is our closest star.
sun: The star at the center of Earth’s solar system. It is about 27,000 light-years from the center of the Milky Way galaxy. Also a term for any sunlike star.
sustainable: (n. sustainability) An adjective to describe the use of resources in a such a way that they will continue to be available long into the future.
theory: (in science) A description of some aspect of the natural world based on extensive observations, tests and reason. A theory can also be a way of organizing a broad body of knowledge that applies in a broad range of circumstances to explain what will happen. Unlike the common definition of theory, a theory in science is not just a hunch. Ideas or conclusions that are based on a theory — and not yet on firm data or observations — are referred to as theoretical. Scientists who use mathematics and/or existing data to project what might happen in new situations are known as theorists.
turbine: A device with extended arm-like blades (often curved) to catch a moving fluid — anything from a gas or steam to water — and then convert the energy in that movement into rotary motion. Often that rotary motion will drive a system to generate electricity.
universe: The entire cosmos: All things that exist throughout space and time. It has been expanding since its formation during an event known as the Big Bang, some 13.8 billion years ago (give or take a few hundred million years).
uranium: The heaviest naturally occurring element known. It’s called element 92, which refers to the number of protons in its nucleus. Uranium atoms are radioactive, which means they decay into different atomic nuclei.
virus: Tiny infectious particles consisting of genetic material (RNA or DNA) surrounded by protein. Viruses can reproduce only by injecting their genetic material into the cells of living creatures. Although scientists frequently refer to viruses as alive or dead, in fact many scientists agree that viruses are not truly alive. They don’t eat as animals do or make their own food as plants do. A virus must hijack the cellular machinery of a living cell to survive.
wave: A disturbance or variation that travels through space and matter in a regular, oscillating fashion.