| actinide series |
the series of chemical elements, mostly synthetic and all radioactive, that have from eighty-nine to 103 protons per atom. |
| aldehyde |
in chemistry, any of a group of organic compounds, such as formaldehyde, the molecule of which contains a terminal carbon atom bound separately to a hydrogen and an oxygen atom. |
| -amine |
containing the amino group, which has one atom of nitrogen and two of hydrogen. |
| atomic bomb |
an extremely destructive weapon, the explosive power of which derives from the immense amount of energy suddenly released when the nuclei of uranium 235 or plutonium atoms are split; atom bomb. |
| atomic energy |
the energy that is released by an atom in nuclear reactions such as fission or fusion. [1/2 definitions] |
| atomic mass unit |
a unit equal to one twelfth of the mass of an atom of the most abundant kind of carbon, equal to 1.6605 times 1024 gram. |
| atomic number |
the number of protons or positive electrical charges in the nucleus of one atom of a given element. [1/2 definitions] |
| atomic weight |
the average weight of one atom of a given element, expressed in atomic mass units. |
| at. wt. |
abbreviation of "atomic weight," the average weight of one atom of a given element, expressed in atomic mass units. |
| benzene ring |
the graphic representation of the benzene molecule or its derivatives as a hexagon with a carbon atom at each of its six points, and with attached atoms of hydrogen or other elements. |
| bichloride |
a chemical compound in which there are two atoms of chlorine for each atom of another element or group; dichloride. |
| carbonyl |
a metal compound containing a radical of one atom of carbon and one of oxygen, or this radical itself. |
| carboxyl |
a chemical group containing one atom of carbon, two of oxygen, and one of hydrogen, present in many organic acids. |
| covalence |
the number of pairs of electrons that an atom can share with other atoms. [1/2 definitions] |
| cyanide |
a chemical compound that contains one carbon and one nitrogen atom together with another element such as potassium or sodium, both of which form extremely poisonous substances. [1/2 definitions] |
| deuteron |
a particle composed of one proton and one neutron that is equivalent to the nucleus of a deuterium atom and that has a positive charge. |
| dioxide |
a compound containing two atoms of oxygen bound to a single atom of another element. |
| electron |
a negatively charged particle, considered a fundamental unit of matter, that exists independently or outside the nucleus of an atom. |
| element |
any of the substances, now numbering 118, that, being made up of only one type of atom, cannot be chemically separated into simpler substances. [1/6 definitions] |
| ether |
any of a group of compounds in which two hydrocarbon groups are attached to an oxygen atom. [1/4 definitions] |
| excite |
in physics, to raise (an atom, particle, or molecule) to a state of higher energy. [1/5 definitions] |