actinium

[ ak-tin-ee-uhm ]

Phonetic (Standard)IPA

noun

, Chemistry.

a radioactive silver-white metallic element that glows blue in the dark, resembling the rare earths in chemical behavior and valence. : Ac; : 89; : 227.

actinium

/ ækˈtɪnɪəm /

a radioactive element of the actinide series, occurring as a decay product of uranium. It is used as an alpha-particle source and in neutron production. Symbol: Ac; atomic no: 89; half-life of most stable isotope, ²²⁷Ac: 21.6 years; relative density: 10.07; melting pt: 1051°C; boiling pt: 3200 ± 300°C

actinium

/ ăk-tĭn′ē-əm /

A silvery-white, highly radioactive metallic element of the actinide series that is found in uranium ores. It is about 150 times more radioactive than radium and is used as a source of alpha rays and neutrons. Its most stable isotope has a half-life of about 22 years. Atomic number 89; melting point 1,050°C (1,922°F); boiling point (estimated) 3,200°C (5,792°F); specific gravity (calculated) 10.07; valence 3.
See Periodic Table

First recorded in 1900–05; actin- + -ium

C19: New Latin, from actino- + -ium

On Rutherford's theory then, actinium should always accompany uranium and radium, but in very subordinate amount.

For if actinium was an independent element we would be sure to find actinium haloes.

The element has since been found in nature as a small constituent of the natural decay of actinium.

The emanation deposits two successive disintegration products actinium-A and actinium-B.

What is the final non-active product of the series of changes we have traced from uranium through actinium and radium?

April 23, 2024inveterate

[in-vet-er-it ]

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