Terms
- Anion
- A negatively charged ion.
- Atom
- The smallest unit of matter that retains the properties of an element.
- Atomic Mass
- The total mass of an atom, which is the mass in grams of one mole of the atom.
- Atomic Nucleus
- An atom’s central core, containing protons and neutrons.
- Atomic Number
- The number of protons in the nucleus of an atom, unique for each element and designated by a subscript to the left of the elemental symbol.
- Cation
- An ion with a positive charge, produced by the loss of one or more electrons.
- Chemical Bond
- An attraction between two atoms, resulting from a sharing of outer-shell electrons or the presence of opposite charges on the atoms. The bonded atoms gain complete outer electron shells.
- Chemical Equilibrium
- In a reversible chemical reaction, the point at which the rate of the forward reaction equals the rate of the reverse reaction.
- Chemical Reaction
- A process leading to chemical changes in matter; involves the making and/or breaking of chemical bonds.
- Compound
- A substance consisting of two or more elements in a fixed ratio.
- Covalent Bond
- A type of strong chemical bond in which two atoms share one or more pairs of valence electrons.
- Dalton
- A measure of mass for atoms and subatomic particles.
- Electron
- A subatomic particle with a single negative charge. One or more electrons move around the nucleus of an atom.
- Electron Shell
- An energy level represented as the distance of an electron from the nucleus of an atom.
- Electronegativity
- The attraction of an atom for the electrons of a covalent bond.
- Element
- Any substance that cannot be broken down to any other substance.
- Energy
- The capacity to do work (to move matter against an opposing force).
- Energy Level
- Any of several different states of potential energy for electrons in an atom.
- Hydrogen Bond
- A type of weak chemical bond formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule.
- Ion
- An atom that has gained or lost electrons, thus acquiring a charge.
- Ionic Bond
- A chemical bond resulting from the attraction between oppositely charged ions.
- Ionic Compound
- A compound resulting from the formation of an ionic bond; also called a salt.
- Isotope
- One of several atomic forms of an element, each containing a different number of neutrons and thus differing in atomic mass.
- Mass Number
- The sum of the number of protons and neutrons in an atom’s nucleus.
- Matter
- Anything that takes up space and has mass.
- Molecular Formula
- A type of molecular notation indicating only the quantity of the constituent atoms.
- Molecule
- Two or more atoms held together by covalent bonds.
- Neutron
- An electrically neutral particle (a particle having no electrical charge), found in the nucleus of an atom.
- Nonpolar Covalent Bond
- A type of covalent bond in which electrons are shared equally between two atoms of similar electronegativity.
- Orbital
- The three-dimensional space where an electron is found 90% of the time.
- Potential Energy
- The energy stored by matter as a result of its location or spatial arrangement.
- Periodic Table
- A chart of the chemical elements, arranged in three rows, corresponding to the number of electron shells in their atoms.
- Polar Covalent Bond
- A covalent bond between atoms that differ in electronegativity. The shared electrons are pulled closer to the more electronegative atom, making it slightly negative and the other atom slightly positive.
- Potential Energy
- The energy stored by matter as a result of its location or spatial arrangement.
- Product
- An ending material in a chemical reaction.
- Proton
- A subatomic particle with a single positive electrical charge, found in the nucleus of an atom.
- Radioactive Isotope
- An isotope (an atomic form of a chemical element) that is unstable; the nucleus decays spontaneously, giving off detectable particles and energy.
- Reactant
- A starting material in a chemical reaction.
- Salt
- A compound resulting from the formation of an ionic bond; also called an ionic compound.
- Structural Formula
- A type of molecular notation in which the constituent atoms are joined by lines representing covalent bonds.
- Trace Element
- An element indispensable for life but required in extremely minute amounts.
- Valence
- The bonding capacity of an atom, generally equal to the number of unpaired electrons in the atom’s outermost shell.
- Valence Electron
- An electron in the outermost electron shell.
- Valence Shell
- The outermost energy shell of an atom, containing the valence electrons involved in the chemical reactions of that atom.
- Van Der Waals Interactions
- Weak attractions between molecules or parts of molecules that are brought about by localized charge fluctuations.
