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rhodium

(Encyclopedia)rhodium rōˈdēəm [key], metallic chemical element; symbol Rh; at. no. 45; at. wt. 102.90550; m.p. about 1,966℃; b.p. 3,727±100℃; sp. gr. 12.41 at 20℃; valence +2, +3, +4, +5, or +6. Rhodium ...

aluminum

(Encyclopedia)aluminum ălˌyo͞omĭnˈēəm [key], metallic chemical element; symbol Al; at. no. 13; at. wt. 26.98154; m.p. 660.37℃; b.p. 2,467℃; sp. gr. 2.6989 at 20℃; valence +3. Aluminum is a silver-white...

valence, in chemistry

(Encyclopedia)valence, combining capacity of an atom expressed as the number of single bonds the atom can form or the number of electrons an element gives up or accepts when reacting to form a compound. Atoms are c...

metallurgy

(Encyclopedia)metallurgy mĕtˈəlûrˌjē [key], science and technology of metals and their alloys. Modern metallurgical research is concerned with the preparation of radioactive metals, with obtaining metals econ...

blood

(Encyclopedia)blood, fluid pumped by the heart that circulates throughout the body via the arteries, veins, and capillaries (see circulatory system; heart). An adult male of average size normally has about 6 quarts...

fatigue, in physiology

(Encyclopedia)fatigue, in physiology, inability to perform reasonable and necessary physical or mental activity. Muscle fatigue, for example, results when the contractile properties of muscle are reduced, and conti...

antioxidant

(Encyclopedia)antioxidant, substance that prevents or slows the breakdown of another substance by oxygen. Synthetic and natural antioxidants are used to slow the deterioration of gasoline and rubber, and such antio...

hafnium

(Encyclopedia)hafnium hăfˈnēəm [key], metallic chemical element; symbol Hf; at. no. 72; at. wt. 178.49; m.p. about 2,227℃; b.p. 4,602℃; sp. gr. 13.31 at 20℃; valence +4. Hafnium is a lustrous, ductile, si...

metabolism

(Encyclopedia)metabolism, sum of all biochemical processes involved in life. Two subcategories of metabolism are anabolism, the building up of complex organic molecules from simpler precursors, and catabolism, the ...

niobium

(Encyclopedia)niobium nīōˈbēəm [key], metallic chemical element; symbol Nb; at. no. 41; at. wt. 92.90638; m.p. about 2,468℃; b.p. 4,742℃; sp. gr. 8.57 at 20℃; valence +2, +3, +4, or +5. Niobium is a rare...