A Visual Encyclopedia of the Periodic Table

166

The Oxygen Group

Oxygen

O

8

Oxygen is the most common element in

Earth’s crust. Oxygen and its compounds make

up half of all rocks and minerals on our planet.

In the atmosphere, pure oxygen makes up

around one-fifth of the air. This element is a

transparent gas. Life on Earth depends on

oxygen for survival. Animals breathe in air to

collect the oxygen in it. Our bodies’ cells then use

that oxygen to break apart sugars to release

energy, which powers our bodies. Another

process that involves oxygen is the burning

reaction called combustion, in which oxygen

Streaks of light adorn the sky as

atoms of oxygen in the air are hit by a

stream of particles blasting from the Sun.

Northern lights

Each water

molecule has two

atoms of hydrogen

and one of oxygen.

Water

This glass sphere

traps pure oxygen,

which produces a

silver-blue glow

when electrified.

Plants release

oxygen in sunlight.

Sunflowers

8 8 8

State: Gas

Discovery: 1774

Flames are

produced when

oxygen reacts with

fuel, such as wood.

P

ur

e^

ox

yg

en

in

a^

gla

ss^ s

phere

Forms

F

ir

e

The flame goes out

when the oxygen

supply is cut off.

WHAT IS COMBUSTION?

Combustion is a chemical reaction that

produces heat and light. Oxygen is essential

for combustion to take place.

Candle wax is made of a

flammable carbon compound,

which acts as a fuel.

A beaker is placed over

a candle, starving the

flame of oxygen.

The flame is steady

in the presence of oxygen.

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