Download Nuclear Decay (Radioactivity)

Nuclear Decay (Radioactivity)
Subatomic particles



Electron -negatively charged
particle found outside the nucleus.
Proton – positively charged
subatomic particle found inside the
nucleus.
Neutron – Neutrally charged (no
charge) subatomic particle found
inside the nucleus.
Some Surprises



A neutron is a proton with a
captured electron.
A neutron can become a proton by
losing that electron.
That electron, when it comes flying
out of the nucleus, will be called a
beta particle. It’s symbol is the
Greek letter β.
Beta radiation

What would happen to the nuclear
make-up as a result of beta
radiation? Consider: carbon – 14.
-+ = neutron
+
+-+
+ -+
-+ +-++
+
-+
+
-+ -+
= proton
Beta radiation

What would happen to the nuclear
make-up as a result of beta
radiation? Consider: carbon – 14.
-+ = neutron
+
+-+
+ -+
-+ +-++
+
-+
+
-+ - +
= proton
Beta radiation


How many protons does it have
now?
What is its mass number?
-+ = neutron
+
+-+
+ -+
-+ +-++
+
-+
+
-+ +
= proton
Alpha Radiation

An alpha (α) particle is the same as
a helium nucleus and is therefore
symbolized by: 42 He
-+ = neutron
+
= proton
-+
-+ + + -+
+ -+
+
+ -+ +-+
+
-+ -+
-+
+ -+ -+
+
-+ -+ + ++ + +
++
-+ -+
+ -+
+
-+
-+ +-+-+
-+ +
+ -+
++
+ -+ -+
Alpha Decay

When an alpha particle is emitted
from a nucleus, what is left?
Consider Uranium – 238.
238
92
U
XTh
234
90
+
4
2
He
Which kind of decay is represented by
each change?


I – 130 → Xe – 130
Am-241 → Np-237
Three Kinds of Decay



Alpha – a helium nucleus, cannot
penetrate paper.
Beta - an electron which is emitted
from the nucleus. Can penetrate
paper, but cannot penetrate
aluminum foil.
Gamma ray – not a particle. 50%
emitted will penetrate 1cm of lead.