The number of protons in the nucleus of an atom. This determines an element's structure, properties and location on the periodic table of elements.

A mass unit that is exactly 1/12th the mass of a carbon 12 (C12) atom (approximately 1.67E-24g).

The average mass of all nuclides of an element determined by the proportions in which each nuclide of the element are present within the earth and its atmosphere.

The smallest possible unit of matter that still maintains an element's identity during chemical reactions. Atoms contain one or more protons and neutrons (except hydrogen (H), which normally

Species of subatomic particles that have the same mass and spin as normal particles, however, they have opposite electrical charges from their normal matter counterparts. In the case of anti

A negatively charged ion.

One ten-billionth of a meter (10-10m or 0.0000000001 m) or 1/10th of a nanometer.

Consists of the nucleus of an atom of helium (two protons and two neutrons) and is sometimes emitted from the nucleus of some atoms as part of those atoms' radioactive decay. Alpha particles

A metal in the first column of the periodic table (i.e., lithium, sodium, potassium, rubidium, cesium and francium). With the exception of francium, these metals are all soft and silvery. Th

Elements in the second column (from the left) of the periodic table all fall into this series. These elements are in general white, differing by shades of color or casts; they are malleable,

The fourteen elements in the bottom row of the inner-transition elements of the periodic table that follow the element actinium (Ac #89). Some reference sources include actinium in this seri

Compounds that contain hydrogen (H #1) and when dissolved in water (H2O), they increase the concentration of hydrogen ions, H+ (hydronium ions H3O+). Acids are proton donors. Substances with

In measurement indicates that a set of measurements are close to the true answer, though they are not necessarily precise.

The difference between the approximate and exact value in any calculation.

Matter in the form of particles, the chief components of which are soot and unburned hydrocarbons.

A method of positioning and securing the interior space, luggage compartment, and so forth, depending on the positioning of the engine, chassis, and other parts of the automobile.

One method of performing safety control of chemical substances, it consists of papers containing information on the substance's name, chemical and physical properties, dangers, harmfulness,

International standards for environmental management systems set forth by the International Organization for Standardization. It is one part of the 14000 Series. ISO 14001 certification can

A harmful substance produced by burning polyvinyl chloride, table salt, and other substances containing chlorine under inappropriate conditions. It has been noted as an endocrine disrupter,

Waste generated during chemical treatment processes. Since it contains phosphorus, nickel, and other inorganic substances, it cannot be burned. It is disposed of in controlled type landfills