A Visual Encyclopedia of the Periodic Table

122

Actinides

Sitting next to uranium in the periodic

table, neptunium was named after the

planet Neptune. It exists in small amounts

in radioactive ores, such as aeschynite.

It forms during nuclear explosions and

was first identified inside a machine called

a cyclotron. There are no known uses

for neptunium.

Named after the planet Uranus, uranium was

the first known radioactive element. In the early

20th century, some manufacturers used uranium

in glass bowl glazes, only to realize later

that it was a harmful metal.

An unstable form, called

uranium-235, is used as

fuel in nuclear

reactors and

in atomic

bombs.

Chunk of pure uranium

Uraninite

Uranium mixed into

glass makes this bowl

glow bright green under

ultraviolet (UV) lamps.

These black sections

contain uranium dioxide, which

is the main source of uranium.

The radioactive

elements in this

mineral decay to

form neptunium.

This cyclotron,

built in 1938, was

used to discover

neptunium.

This sample of pure

uranium is waste

from a nuclear plant.

Cyclotron at the University

of California, Berkeley, USA

Uranium

Neptunium

Glass bowl

State: Solid

Discovery: 1789

93 93 144

State: Solid

Discovery: 1940

U

92

Np

93

U

ra

n

in

it

e

92 92 146

122-123_Uranium_Neptunium_Plutonium_Americium.indd 122 12/12/16 5:39 pm