2020-04-02_Science_Illustrated

ARE C

Water molecules

bind to each other

3

The positively-charged

hydrogen atoms attract

negatively-charged oxygen

atoms of other water molecules.

Thanks to the hydrogen bonds

between the water molecules,

liquid water forms.

The boiling point

is unusually high

The more a molecule weighs, the higher

its boiling point. But water breaks the

rules. The compound hydrogen selenide

weighs more than water, but has a boiling

point of -42°C. Water, being lighter, ought to

boil at an even lower temperature, but due to

its hydrogen bonds, the water molecules

remain intact until 100°C, something which

was vital for life being able to originate.

Water produces ‘film’

on the surface

At the water’s surface, the

water molecules cannot

form hydrogen bindings in all

directions, so they bind more

efficiently to nearby molecules.

The result is surface tension, so

that water forms drops, and

some insects can walk on water.

Ice insulation keeps

marine animals warm

The density of ice is lower than that of

liquid water, because water molecules

form hexagonal structures at a temperature of

0 °C. This increases the distance between

molecules, so ice is less dense than water, settling

on top of the water. Ice functions as insulation,

keeping the water under the ice liquid and

making sure that animals and plants can survive.

ICE

0 degrees

HYDROGEN BONDS

WATER

ICE

KEY ELEMENT

100 degrees

VAPOUR

SHU

TTE

RST

OCK

(^) & (^) L
OTT
E (^) FR
EDS
LUN
D
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