a series of elements whose atomic weights were known
21liquid — liquidly, adv. liquidness, n. /lik wid/, adj. 1. composed of molecules that move freely among themselves but do not tend to separate like those of gases; neither gaseous nor solid. 2. of, pertaining to, or consisting of liquids: a liquid diet. 3 …
22Europe, history of — Introduction history of European peoples and cultures from prehistoric times to the present. Europe is a more ambiguous term than most geographic expressions. Its etymology is doubtful, as is the physical extent of the area it designates.… …
23science, history of — Introduction the history of science from its beginnings in prehistoric times to the 20th century. On the simplest level, science is knowledge of the world of nature. There are many regularities in nature that mankind has had to… …
24Kilogram — Kg redirects here. For other uses, see Kg (disambiguation). Kilogram A computer generated image of the international prototype kilogram (IPK). The IPK is the kilogram. The IPK, which is roughly the size of a golf ball, sits here alongside a ruler …
25Periodic table — This article is about the periodic table of the elements . For other uses, see The Periodic Table. The periodic table of the chemical elements (also known as the periodic table or periodic table of the elements) is a tabular display of the 118… …
26nuclear weapon — an explosive device whose destructive potential derives from the release of energy that accompanies the splitting or combining of atomic nuclei. [1945 50] * * * or atomic weapon or thermonuclear weapon Bomb or other warhead that derives its force …
27light — light1 lightful, adj. lightfully, adv. /luyt/, n., adj., lighter, lightest, v., lighted or lit, lighting. n. 1. something that makes things visible or affords illumination: All colors depend on light. 2. Physics …
28rare-earth element — /rair errth /, Chem. any of a group of closely related metallic elements, comprising the lanthanides, scandium, and yttrium, that are chemically similar by virtue of having the same number of valence electrons. Also called rare earth metal. [1955 …
29Wave–particle duality — Quantum mechanics Uncertainty principle …
30Radon — This article is about the chemical element. For other uses, see Radon (disambiguation). astatine ← radon → francium Xe ↑ Rn ↓ Uuo …
