Wikijunior:The Elements/Glossary

alchemy: a science that attempts to change one element into another.
alloy: a substance that is a mixture of two or more metals.
amalgam: any metallic alloy that has mercury in it.
atom: any one of the smallest particles of an element that has the chemical properties of the element. Atoms are neutral, being neither positive nor negative by having the same amount of electrons and protons.
chemical bond: a bond (like covalent or ionic bonds) between atoms or ions that forms a molecules.
chemical substance: a substance that is made of only one type of molecule.
chemistry: the science of the properties, composition, and transformation of substances.
compound: a special type of molecule that is made up of at least two different elements.
condensation: the changing of a gas to a liquid.
conductive: able to pass heat or electricity from one side to the other.
corrosion: the act of eating away at gradually, as by rust or chemical action.
covalent bond: a bond between atoms formed by sharing of electrons.
deposition: the act of changing a gas directly to a solid.
ductile: capable of being drawn out into threads, as some metals.
electron: a negatively charged particle that is a component of all atoms. Electrons are approximately organized in shells. They are also as negative as protons are positive.
element: a natural substance which cannot be broken down any further by chemical processes.
emulsion: a liquid, as milk, in which minute particles remain in suspension.
fusibility: the ability to join separate parts together as one.
gas: a fluid and elastic form of matter tending to expand indefinitely.
halogens: elements that have seven valence electrons, all of which are very reactive.
ion: An ion is an electrically charged particle. Some atoms can bond with each other ionically to form molecules. Certain atoms are allowed to have certain ionic charges so that they may bond with other atoms having opposite ionic charges.
ionic bond: a bond between ions.
liquid: a compressed mass of particles that flow freely.
luster: how much a material shines.
malleable: capable of being hammered or shaped without breaking.
matter: any substance that has mass and volume.
melting: the process of converting a solid to a liquid, usually by adding heat to the solid.
metal: one of the elements with the characteristics of luster, ductility, malleability, fusibility, and conductivity of heat and electricity.
mixture: two or more different substances that are put together but still retain their own properties. An example is salt and pepper.
molecule: a particle formed by two or more atoms that are chemically bonded together that therefore has new properties not necessarily possessed by the components. An example is a water (H₂O) molecule, which is made of the explosive hydrogen and oxygen.
neutron: an uncharged particle having slightly more mass than a proton. It is located in the nucleus of an atom.
nucleus: the center of an atom. It contains all the protons and neutrons in the atom.
ore: a mineral in its natural state.
oxide: a compound that contains oxygen and at least one other element.
particle: a very tiny piece, such as an electron, atom, or molecule.
proton: a positively charged particle in the nucleus of an atom. Protons are as positive as electrons are negative.
radioactive: A radioactive substance releases particles like beta particles (electrons from the nucleus) over time. Eventually, most of the substance will have changed into a different element.
solid: a form of matter that resists changes to both shape and volume.
solution: a mixture of solids, liquids, and/or gases that joins together evenly.
sublimation: the act of changing a solid directly to a gas.
valence electron: an electron that is on the outer-most shell.
vaporization: the changing of a liquid to a gas.