- 1
Radioactivity is the sending-out itself. When the centre of an atom breaks apart, it can throw off radiation — a form of energy — and we call that sending-out radioactivity. If radioactive says what a thing is like, radioactivity names the process or the property: how much of that sending-out is happening. You meet the word in science class, in news about nuclear power or bombs, and in hospital talk. It is not a kitchen-table word. After an accident, headlines use it for the danger in air, water, or soil. We say “This waste is radioactive,” but “The radioactivity of this waste is high.”
放射性
組成radioactive + -ity (turns the adjective into the name of the quality). Same idea as radio- + activity.
同家族的字
- radioactivethe adjective this noun is built from
- activitythe same pattern: the “doing” named as a noun
原始詞典資料2 筆記錄
以下是外部詞典記錄的用法，原文照列，我們還沒有寫成教學內容。上面的說明才是我們自己寫的；有些用法可能上面已經講過了。
radioactivitynoun/ˌreɪdɪəʊakˈtɪvɪti/
- 1
Spontaneous emission of ionizing radiation as a consequence of a nuclear reaction, or directly from the breakdown of an unstable nucleus.
- Today, no one would intentionally smear radioactive materials on their face, but in 1933, the dangers of radioactivity were not yet fully understood.
- 2
The radiation so emitted; including gamma rays, alpha particles, neutrons, electrons, positrons, etc.
資料來源：英文維基詞典 English Wiktionary（CC BY-SA 4.0）。 原文照列，未經改寫。