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Quiz "Chemical elements"

Chemical elements

a hard malleable ductile greyish-white element. It occurs principally in wolframite and scheelite and is used in lamp filaments, electrical contact points, X-ray targets, and, alloyed with steel, in high-speed cutting tools. Symbol: W; atomic no: 74; atomic wt: 183.85; valency: 2–6; relative density: 19.3; melting pt: 3422±20°C; boiling pt: 5555°C

Chemical elements

a synthetic radioactive element produced in small quantities by cold fusion in a linear accelerator. Symbol: Ds; atomic no: 110

Chemical elements

a toxic silvery-white metallic element occurring chiefly in carnotite and vanadinite and used in steel alloys, high-speed tools, and as a catalyst. Symbol: V; atomic no: 23; atomic wt: 50.9415; valency: 2–5; relative density: 6.11; melting pt: 1910±10°C; boiling pt: 3409°C

Chemical elements

a toxic metalloid element, existing in several allotropic forms, that occurs principally in realgar and orpiment and as the free element. It is used in transistors, lead-based alloys, and high-temperature brasses. Symbol: As; atomic no: 33; atomic wt: 74.92159; valency: –3, 0, +3, or +5; relative density: 5.73 (grey); melting pt: 817°C at a pressure of 3MN/m2 (grey); sublimes at 613°C (grey)

Chemical elements

a white metallic transuranic element artificially produced from plutonium. It is used as an alpha-particle source. Symbol: Am; atomic no: 95; half-life of most stable isotope, 243Am: 7.4 × 103 years; valency: 2,3,4,5, or 6; relative density: 13.67; melting pt: 1176°C; boiling pt: 2607°C (est)
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