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A small amount of radioisotope replacing a nonradioactive isotope of the element in a compound whose path (for example, in the body) or whose decomposition products are to be monitored by detection of radioctivity, also called a radioactive label.

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Isotopes

Two or more forms of atoms of the same element with different masses, atoms containing the same number of protons but different numbers of neutrons.

Heat

A form of energy that flows between two samples of matter because of their differences in temperature.

Bonding Orbital

A molecular orbit lower in energy than any of the atomic orbitals from which it is derived, lends stability to a molecule or ion when populated with electron.

Quantum Mechanics

Mathematical method of treating particles on the basis of quantum theory, which assumes that energy (of small particles) is not infinitely divisible.

Zinc

Discovered: known in India and China before 1500 and to the Greeks and Romans before 20 BC as the copper-zinc alloy brass
Origin: The name is derived from the German ‘Zink’.
Atomic no: 30
Mass No: 65
Description: A grey metal with a blue tinge. World production exceeds 7 million tons a year, and it is used to galvanise iron to prevent it rusting. It is also employed in alloys and batteries, and as zinc oxide to stabilise rubber and plastics. Zinc is essential for all living things, and is important for growth and development. The average human body contains about 2.5 grams and takes in about 15 milligrams per day. Some foods have above average levels of zinc, including herring, beef, lamb, sunflower seeds and cheese.

Lewis Dot Formula (Electron Dot Formula)

Representation of the core of a molecule, ion or formula unit by showing atomic symbols and only outer shell electrons.

Absolute Entropy (of a substance)

The increase in the entropy of a substance as it goes from a perfectly ordered crystalline form at 0 °K (where its entropy is zero) to the temperature in question.

Entropy is a measure of the “dilution” of thermal energy.

Reducing Agent

The substance that reduces another substance and is oxidized.

Heteronuclear

Consisting of different elements.

Ion Product for Water

Equilibrium constant for the ionization of water, Kw = [H3O+][OH-] =1.00 x 10-14 at 25 °C.