>> host: Welcome back
to "Chemistry Matters,"
and our unit
on Atomic Structure.
In the previous video
on this play list,
we talked about different trends
of the Periodic Table,
such as electronegativity,
atomic radius,
and ionization energy.
I hope you remember
that ionization energy
is the amount of energy required
to remove one valence electron
from an atom.
Electrons are little,
tiny particles of matter.
So does removing one or two
electrons really matter
in the grand scheme of things?
Oddly enough, while it doesn't
change the mass of an atom
significantly,
it makes a huge difference
in the chemical reactivity
of an atom.
If you've ever thrown a coin
into a fountain in a park
or at the mall,
I bet you saw lots of pennies
in the bottom of the fountain.
These pennies have a lot
of neutral copper in them.
Copper,
with all of its electrons.
This blue crystal
is Copper (II) sulfate.
Instead of being neutral,
the copper in
Copper (II) sulfate
is a 2+ cation.
I'm going to drop a penny
into the water,
and then I'll add
the copper (II) sulfate.
Watch this.
Now, nothing's happened
to the penny.
Copper doesn't dissolve
in water.
But the copper (II) sulfate
does dissolve.
It's already started
turning the water blue.
Losing just two electrons
means the copper cation
dissolves in water.
Electrons are really important.
Chemists and physicists
have done lots and lots
of research to determine
where electrons are located
in atoms,
and how they're gained and lost.
Based on all of that research,
chemists have developed
a shorthand notation
for describing the location
and energy of an electron
called electron configuration.
Knowing the order in which
electrons fill the various
energy levels helps us predict
and understand the physical
and chemical properties
of different atoms.
For example, why does Lithium
always form a 1+ ion,
while fluorine forms only
a 1- ion.
The reason lies in how
the atom's electrons
are arranged.
These electron arrangements
are very important,
and are the focus of an activity
we'll do with the students
in our classroom.
This activity will introduce you
to two different models
of electron arrangement.
As you begin investigating
the electron configuration
of additional elements,
you're going to need a stack
of these electron configuration
cards, which you can download
from our "Chemistry Matters"
toolkit.
The electron configuration cards
are different from the element
cards you used earlier
in this unit.
You'll see that some
of the electron configuration
cards have information
that you're familiar with,
like element names and symbols.
Some cards have new information.
While we don't expect you
to fully understand these
new symbols yet, we do want you
to think about how they combine
to give us information
about the location and energy
of an electron.
I'll give you a brief overview
of the new symbols
and what they stand for.
Arrows are used as symbols
for electrons.
Lines under the arrows
represent the orbital
holding the electron.
Letters combined with numbers
represent energy sublevels
within the primary
energy levels.
And look for two types
of numbers:
coefficients, which tell
us how many energy levels
an atom has,
and exponents, which show us
how many electrons are in
a particular energy sublevel.
If you've gotten your energy
configuration cards
from the "Chemistry Matters"
Toolkit and cut them up,
then you can start by looking
for ways to separate the cards
into groups.
See if you can figure out
how the cards are related
to each other
before you sort them.
For example, maybe you can
figure out how a pattern
of numbers and arrows
represents an element,
rather than simply making
individual piles of all
the element symbols,
and all the arrows.
So grab your cards
and start organizing.
Once you think you've cracked
the code, go to the next video
on the play list and catch up
with our students to see
what we can learn about
electron configuration.