I'm Cathy Renaud,
and I'm a science teacher
at Greenhills School
in Ann Arbor, Michigan.
And I'm delighted to be here
to talk to you a little
bit about the periodic table.
On the wall behind me
is a huge periodic table
I use when I'm teaching
and it's a wonderful, wonderful
tool that might intimidate
a few people when
you first look at it.
But it's organizational
and we use
organization in our lives.
We like to categorize
and that's what this does.
It categorizes the elements
that we know into a useful tool.
And on a daily basis, humans
like to categorize and organize.
And if you go to a grocery store
or a hardware store,
it's organized.
When you walk in,
you can find the dairy section
or the bakery section,
you can find the electrical,
you can find the plumbing.
That's what this
periodic table does.
It provides an organizational
mechanism
for scientists
and some non-scientists.
Overall, when you look at this,
you might be overwhelmed
by all the information,
but if you separate it
and you break it down,
we have some colors associated
with it.
In this particular one,
the black indicate
they exist as solids,
the red indicate they exist
as gases in the natural form,
the blue indicate that
they exist as liquids.
The ones that exist
in this outline form
are non-naturally occurring.
They are made by humans
and they're very short-lived.
So, the overall
organization that we see,
we have metals,
we have non-metals.
The metals are over here
on this side,
the non-metals
are on the far right
and we have a section in between
that are called
semimetals or metalloids.
Now, in the metal section,
we have three key ones that
I want to point out right now,
copper, silver, and gold.
They're our coinage metals
and when we look at them,
if you think of them,
they're shining,
they're malleable,
meaning you can hammer
them into sheets.
They're ductile,
you can pull them into wires.
They conduct heat,
they conduct electricity.
They're very useful to us.
So, that's the characteristics
we associate with metals.
On the opposite side,
the non-metals have
characteristics the metals...
opposite characteristics
of the metals.
They are not shiny,
they're not ductile,
they're not malleable.
They're brittle actually
if you hammer them.
They don't conduct
heat and electricity.
The semimetals or the
metalloids in between,
they're the ones that have some
characteristics of both
and provide some unusual
opportunities
for people in the world to use
such as silicon,
element number 14,
which is a huge component
within your cell phones
and your computers.
Now, the periodic table
itself in its current form
is very different
from what developed
over a very long period of time
with many scientists
contributing.
The current version
has several elements
beyond what our original
scientists were working on.
Dmitri Mendeleev,
in the 1800s, late 1800s,
is given the majority of the
credit for the organization
of our current periodic table,
and he was trying
to find a way to organize
what he understood
about the elements.
And what he did
was something
no other scientist
at the time did.
He predicted the existence
of elements yet to be discovered
and he left gaps
in the periodic table.
And he predicted
their properties.
He predicted how they would
combine with other elements,
some masses
associated with them,
and when those elements were
discovered several years later,
the information he proposed
lined up with the elements
and he was dead-on
in terms of his proposed
characteristics and properties.
So, he is given
the majority of credit
for the current organization
of the periodic table.
Now, his organization was based
on atomic mass and if you look
at the numbers in these
lower portions here
that are written in red,
that's the atomic mass.
It's composed of
the number of protons
and the number of neutrons.
The atomic number
in the upper right-hand corner
is the number of protons.
That was a newer addition.
Henry Moseley,
in the early 1900s,
was the one that came up
with that information
and eventually just
determined that that was just
the mass of the protons or the
number of protons, I'm sorry.
So, the number of protons
is what we have now used
to organize the elements within
this periodic table.
If you also notice,
these are not whole numbers.
We've got some
decimal places in there.
And if you've
ever heard of isotopes,
isotopes are an element
with different forms,
same number of protons but
different number of neutrons.
And the most common
form is carbon 12.
That's what the majority
of our bodies consists of,
but there's also carbon 13
and carbon 14.
And if you've ever
heard of carbon 14 dating,
that is the element...
the isotope of carbon
that decays or
breaks down over time
and we can compare it to
what is in the atmosphere,
so it allows us to date certain
items that are carbon based.
Within the
periodic table itself,
we have this
wealth of information
that to my knowledge,
nobody has memorized.
It's not worth it.
So, what you use it for is
looking at how things might
combine with one another
and what may not work at all.
I use it in my chemistry class,
pharmacists will use it,
doctors will use it,
engineers will use it,
but those are the obvious people
but there are others
that may use this as well.
If you're an artist,
if you paint,
if you do pottery
or if you're a jeweler,
that would be a common thing
that you may want to use as well
because you can find out a
lot about the materials
that you use in your world.
So, it's a tool,
it's beautiful,
and I hope that you
find some beauty
in this piece of information
that will help you in your life.
