noun
Chemical element; also referred to as ヨード in some contexts.
See also: ヨード
ヨウ素は消毒に使われる。
Iodine is used for disinfection.
海藻にはヨウ素が多く含まれている。
Seaweed contains a lot of iodine.
ヨード is a loanword from German 'Jod', often used in medical and everyday contexts, while ヨウ素 is the standard chemical term.
From 沃 (an older kanji for iodine, now replaced by ヨウ) + 素 (element). The reading よう is derived from the first syllable of 'iodine'.