Let’s go over the
homework,
pg. 100, Check-in
& HMK Qs 1-3
Check-in:
Use your graph to determine how
many neutrons you would need to
make a stable element with 75 protons
Anywhere between
92 & 115 neutrons.
Check-in:
How many neutrons
would make a
radioactive element
with 75 protons?
92 or 115
neutrons
Check-in:
Explain the relationship between the
words atom and isotope.
Atoms can have many
isotopes (different #
of neutrons)
1. Imagine an atom with a nucleus of 31
protons and 31 neutrons. Does this
represent an element? Why or why not?
Yes! Gallium.
It falls within
the band of
stability.
2. Find five radioactive elements on
the periodic table. Name them.
Determine the neutron to proton ratio
of each atom.
Examples:
Any element with more
than 83 protons.
+
Radon – 222 86 p , 136 n
3. How many protons could a stable
atom with 90 neutrons potentially
have? Which elements would these be?
60-75 protons
Elements: Nd  Re