The New Childrens Encyclopedia

IT’S ELEMENTARY

229

SCIENCE

■ Group Transition metals

■ Discovery date Unknown

(prehistoric times)

■ Melting point 2,800ºF

(1,538ºC)

■ Boiling point 5,182ºF

(2,862ºC)

Iron is a versatile and abundant metal.

We use it to build bridges and make

machines and flatware. Iron is vital to

your well-being. It gives red blood

cells their color and helps to carry

oxygen around your body. The center

of the Earth is made of iron.

Iron

Ferrum

Gold

Aurum

■ Group Transition metals
■ Discovery date
Unknown (prehistoric
times)
■ Melting point 1,947ºF
(1,064ºC)
■ Boiling point 5,173ºF (2,856ºC)

Gold gets people excited. It has been

prized and valued since prehistoric

times and turned into many crowns,

idols, and crosses over the centuries.

Gold never loses its shine and is easy

to melt and mold. It is measured in

carats—pure gold is 24 carats.

Helium

Helium

■ Group Noble gases

■ Discovery date 1868

■ Melting point -458ºF (-272ºC)

■ Boiling point -452ºF (-269ºC)

Helium is the second most

abundant element in the

universe, after hydrogen. It was

discovered in space, before we

found it on Earth. It weighs very

little and is used to make things

float, such as airships and balloons.

It is also used in liquid form as a

coolant in big scientific computers.

WHO’S WHO?

■ Robert Boyle (1627–1691) was a

British scientist who laid the foundation

for modern chemistry and proposed the idea

of elements.

■ Henry Cavendish (1731–1810) was

the first scientist to prove water was

not an element, but a compound.

■ Joseph Priestly (1733–1804) was

a clergyman and scientist. He discovered

several gases, including oxygen.

■ Alfred Bernhard Nobel (1833–1896)

was an explosives scientist. He created

dynamite and founded the five Nobel prizes.

■ Marie Curie (1867–1934) was famed

for her work on radioactivity, and discovered

polonium and radium.

Mercury

Hydragyrum

■ Group
Transition
metals
■ Discovery date
Pre-1500 BCE
■ Melting point -38ºF (-39ºC)
■ Boiling point 674ºF (356ºC)

Mercury is poisonous, although in

ancient times it was thought to have

healing and life-giving properties.

Early chemists (alchemists) once

thought it held the secret to making

gold. At room temperature, mercury

is a liquid.

Carbon

Carbo

■ Group Nonmetals

■ Discovery date Unknown

(prehistoric times)

■ Melting point

diamonds 6,917ºF (3,852ºC) sublimes 8,672ºF

(4,800ºC)

Carbon is vital to all living things, and

on Earth it is frequently exchanged

between the air, living things, and the

soil, in a never-ending cycle. Carbon

atoms can join together to make coal

and diamonds, as well as with

other elements to make more

than 10 million compounds.

Uranium

Uranium

■ Group Actinides

■ Discovery date 1789

■ Melting point 2,070ºF

(1,132ºC)

■ Boiling point 7,468ºF (4,131ºC)

Uranium is a naturally occuring

radioactive metal and was named after

the planet Uranus. It is refined and

used in industry, nuclear power

plants, and warfare. In the 1940s it

was used to make the atomic bomb

“Little Boy,” which was dropped on

Hiroshima in 1945.

Calcium

Calcis

■ Group Alkaline earth

metals

■ Discovery date

Pre-100 CE

■ Melting point

1,548ºF (842ºC)

■ Boiling point 2,703ºF

(1,484ºC)

Calcium is the most abundant

metal found in living organisms and

is vital for many cellular reactions.

It is also a key component of bones

and shells, giving them strength.

Calcium is also found in milk,

chalk, and seaweeds.

Phosphorus

Lucifer

■ Group Nonmetals

■ Discovery date 1669, by

German chemist Hennig Brand

■ Melting point 111ºF (44ºC)

■ Boiling point 531ºF (277ºC)

This fiery element is very

reactive and so isn’t found

naturally on Earth.

Phosphorus is used to

make matches, fertilizers,

and some weapons. It is

also a component of DNA

and helps to make energy

in your body.

GOLD

Au

79 IRON 26

Fe

HELIUM 2

He

CARBON

C

MERCURY 80 6

Hg

URANIUM

U

92

CALCIUM

Ca

20 PHOSPHORUS

P

15