123
Actinides
This metallic element is
not found in nature. Instead,
it is produced inside nuclear
reactors when uranium or
plutonium atoms are bombarded
with neutrons. Remarkably,
americium is the most common
radioactive element used in the
home. Radioactivity emitted by
americium atoms causes the
air inside smoke detectors to
conduct electricity. When smoke
disrupts the electric current,
an alarm goes off.
This smoke detector contains tiny,
harmless quantities of americium.
1970’s pacemaker
battery
This plutonium
batter y was used
in early pacemakers.
This ore contains
trace amounts
of plutonium.
Hardly any plutonium exists
in nature: most of it has decayed
into other elements over time.
It was discovered during the
development of nuclear
bombs in World War II.
Today, plutonium is used
mostly as a nuclear fuel.
Plutonium
Am
95
Americium
Curiosity
Rover
This Martian rover
uses the heat given off by
a supply of plutonium to
generate electrical power.
95 95 148
State: Solid
Discovery: 1944
94 94 239
State: Solid
Discovery: 1940
Pu
94
Ura
ninite
Sm
ok
e (^) d
ete
cto
r (^) c
om
po
ne
n
t
122-123_Uranium_Neptunium_Plutonium_Americium.indd 123 02/12/16 6:53 pm