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Element Revision Sheet

Iodine (I)

Halogens Block P Group 17 • Period 5
Superhero Identity

"The Antiseptic, a hero who purifies wounds and keeps the body's metabolism in check."

A memorable persona to anchor I in your mind.

Density

4.933

Grams per cm³

Melting Point

113.7

Celsius (°C)

Atomic Radius

198

Radius (pm)

Everyday Connection

Daily Life Link

Iodine is found in the antiseptic used to clean a cut or scrape.

Discovery & History

Year Discovered

1811

Discovered By

Bernard Courtois

Origin of Name

"The name is derived from the Greek ''iodes'' meaning violet."

Technical Properties

Atomic Mass

126.904 u

Standard State

solid

Boiling Point

184.4°C

Electron Configuration

[Kr] 4d105s25p5

1st Ionization Energy

10.451 eV

Electron Affinity

N/A

Oxidation States

[+7 +5 +1 -1]
Appearance

"Iodine is a shiny, purplish-black, crystalline solid."

Did You Know?

1

It has the unusual property of subliming, which means when heated, it turns from a solid directly into a deep violet-colored gas, bypassing the liquid state.

2

Iodine is an essential nutrient for humans, required by the thyroid gland to produce hormones that regulate metabolism. A deficiency causes goiter.

3

Tincture of iodine, an iodine solution, was one of the first and most effective antiseptics for wounds.

4

The element was discovered by accident by Bernard Courtois in 1811 when he was processing seaweed ash to produce saltpeter for Napoleon's armies.

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