iodine

Everyday

1. (science) A chemical element (symbol I, number 53) that forms dark purple-black crystals and a violet gas when heated. tree →
2. A brown liquid made with iodine that is put on cuts to kill germs. tree →
3. (health) A mineral the body needs in tiny amounts to make hormones, found in fish, seaweed, milk and iodised salt. tree →

In the lessons

In science lessons it appears in the periodic table and in the starch test: iodine solution turns from orange-brown to blue-black when starch is present. In health it is a nutrient (iodised salt); in first aid an antiseptic. Phrases: iodine solution, iodine test, iodised salt.

Examples

• We dropped iodine on the bread and it turned blue-black, so it has starch. tree →
• The nurse dabbed iodine on my grazed knee. tree →
• Iodine is element number 53 on the periodic table. tree →
• Seaweed contains a lot of iodine. tree →
• Our salt says «iodised» on the packet. tree →
• When heated, iodine gives off a purple vapour. tree →
• Iodine stains are hard to wash out of clothes. tree →

Note

Uncountable. Pronounced EYE-oh-deen or EYE-oh-dyne. Its symbol is a capital I (one letter). Safety: iodine solution is for use on skin or in experiments, never to drink. Adjective: iodised (UK) / iodized (US).