A Visual Encyclopedia of the Periodic Table

186

The Halogen Group

53 53 74

State: Solid

Discovery: 1811

Betadine

This disinfectant is

applied to wounds to stop

the spread of infection.

The bright red

colour of these

cherries is due to

an iodine dye.

Forms Uses

Iodine is the only halogen that is solid at

room temperature. The element forms a purple

gas when heated, and is named after the Greek

word iodes, which means “violet”. Iodine was first

discovered in seaweed, and many plants and

animals in the sea have high levels of iodine.

Seafood, including crabs and fish, provide the

element in our diet. The human body needs

small amounts of iodine to make an important

substance called thyroxine, which helps us grow.

Iodine is also used to make printing ink, red

and brown food dyes, and disinfectants.

Solid

iodine does

not melt

when heated, but

turns into

a vapour.

This sealed glass

container prevents

iodine from reacting

with air.

These lenses contain

iodine, which filters out

bright, reflected light.

These coloured

inks are made

using iodine

compounds.

Printing ink

a^

gla

ss^

sp

her

e

oP

al

ir

iz

n

(^) g
su
n
gl
as
se
s
This crab
absorbs iodine
from seawater.
Crab
C
an
die
d^ c
herr
ies

Iodine

I

53

Purple

iodine

vapour Purple-black solid iodine

Pu

re

io

din

e^ i

n

186-187_Iodine_At_Ts.indd 186 02/12/16 7:48 pm