
Elements 84-110 are radioactive.

Elements 93-110 are man-made radioactive
elements.
Since these man-made atoms are so big, they
can be created by combining two smaller
atoms together. The protons and neutrons
combine into one large nucleus.

When studying nuclear chemistry, we use the standard symbol notation.
A
X
Z



X is the symbol for the atom
A is the mass number (protons + neutrons)
Z is the atomic number (protons)



Smaller atoms want to have close to the
same number of protons and neutrons. This
is when they are the most stable.
Large atoms with around 83 protons or more
are so large that they too are unstable.
If atoms are too unstable, they will
decompose, or radioactively decay, releasing
different types of particles in order to
become more stable.


Common for heavy radioactive nuclei (above
atomic number 83)
Alpha particle is produced
4
2

He
or

4
2
Not very penetrating; cannot pierce skin;
shielded by paper or clothing
222
Ra  Rn  ____
218
Th He  ____
230
4



Common for elements with high neutron to
proton ratio
Beta particle produced
Beta particle is basically an electron (very
little mass)
0
0
or
e
1


1
More penetrating than alpha; can get
through 1 cm of flesh; may pass through
clothing & damaged skin
Th Pa  ____
234
234
I  e  ____
131
0
1


High energy LIGHT; NOT a particle
Only change in nucleus is in amount of
energy
0
0


Most penetrating of all; can pass through the
body & cause damage shielded only by lead
and/or concrete
U  He Th  ____
238
4
234


Common for lighter elements with low
neutron to proton ratio
Particle has same mass as electron but
OPPOSITE CHARGE
0
1
e
22
Na Ne  ____
22




Common for larger elements with a low
neutron to proton ratio
A nucleus captures one of its OWN electrons
Captured electron joins with a proton in the
nucleus to form a neutron
Gamma rays are always produced with
electron caputre
Hg  e  ____ 
201
0
1
0
0