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Radioactivity: Historical Figures

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Alchemy: A "speculative" chemical system originating in China. It includes the conversion (transmutation) of reactive metals to gold and the discovery of the philosopher's stone. It also provides single cures to diseases and a way to prolong life indefinitely.

Alpha particle: Charged particles emitted from a radioactive atom. Each charged particle consists of two protons and two neutrons.

Atom: This is the smallest unit of an element. It contains a nucleus with neutrons and protons, surrounded by orbiting electrons.

Atomic mass: The mass of an atom usually expressed as atomic mass unit (amu).

Beta particle: (often designated beta rays) Charged particles emitted from a radioactive atom. These particles are identical except for their charge. The charge is classified as positive (positron) or negative (electrons or negatron).

Cathode rays: Electrons originating at the cathodes of gaseous discharge devices. These electrons are often focused in a small area such as a tube and intensified on a surface. The most familiar form of a cathode-ray tube is the television picture tube.

Decay constant: It is the constant C in the equation (I=I0e-ct) to determine the half life of radioactive material.

Electrochemistry: The science dealing with the chemical changes accompanying the passage of an electric current or the source of energy to produce an electrical current. One example is the battery.

Electrons: A negative charged particle that orbits the nucleus of an atom. It is lighter in weight than a proton or neutron.

Elements: An element is a substance made up of atoms with the same atomic number. 75% of the elements are metals and the others are nonmetals. A few examples are oxygen, iron, gold, chlorine, and uranium.

Fluorescence: Electrons absorb energetic radiation (for example ultraviolet light) raising an electron to a higher "Bohr" orbit. The energized electron soon drops down in a series of steps through lower energy states and in the process releases photons at lower energy states corresponding to visible light. The bright color occurs because the photons are concentrated in a narrow range of wavelengths.

Half-life: The period of time it takes for half the nuclei of a radioactive element to undergo decay to another nuclear form.

Magnetic field: All magnetic fields are created by moving electric charge. The single moving electron around a nucleus is a tiny electric current. These orbiting electrons create magnetic fields and their net effect is to provide the atom with a magnetic field.

Naval shell: Refers to a bullet from a gun

Neutron: A particle with no charge that is located in the nucleus of an atom.

Nuclear physics: A branch of physics that includes the study of the nuclei of atoms, their interactions with each other, and with constituent particles.

Patents: A certificate granted by a government given one(s) exclusive right to an invention for a limited period of time. Often during this time others can not make, use, or sell the invention.

Pernicious anemia: A severe blood disease where there is a decrease in number and increase in size of red blood cells. The illness is characterized by pallor, weakness and the inability to absorb vitamin B12.

Piezoelectricity: Electricity resulting from the application of mechanical pressure on a dielectric (a substance with a steady electric field) crystal, for example quartz.

Phosphorescence: Luminescence that persists after a light source has been removed. Materials such as phosphors or phosphorogens are activated from a light source to emit the light in the form of photons of light.

Polonium: A chemical element, Po, atomic number 84. It is used in photographic film to reduce the static charge.

Proton: A positively charged particle that is located in the nucleus of an atom.

Radioactivity: A behavior of an element in which nuclei are undergoing change and emitting particles. This occurs naturally in approximately fifty elements. It can be produced artificially.

Radium: A chemical element, Ra, that has an atomic number 88. It is used as a source of neutrons and makes lightning rods more effective.

Thorium: A chemical element, Th, that has an atomic number 90. It is used in the manufacturing of sun lamps.

Uranium: A chemical element, U, that has an atomic number 92. It reactive with nearly all nonmetals and is used as fuel for nuclear reactors.

X rays: Invisible electromagnetic radiation with wavelengths shorter than visible light. X rays are produced when high energy charged particles collide with other charged particles or with atoms.

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