So starting out here we have magnesium
and uh... you see it's a metal, it's got a little bit of an oxide coating on
here
and so it's got a little bit of black sitting on the surface
but this magnesium metal
and you'll notice that when we put magnesium into water
we're going to test all their activities by dropping the
metals in water
a whole bunch of nothing happens
So, that's magnesium
I'll leave it sit there, we might come back to it later
The next we're going to look at then
is calcium metal.
Calcium metal, you can see here, is shiny again, and it's got a little bit of an
oxide coating here, this stuff is getting a little old
I have to buy some new, next year or so
and
it's a
little bit
soft and I can
dent it with the spoon here,
but I can't really
cut into it
all that well
When we take calcium and drop it into water
should be able to see that it is
bubbling. Quite a bit down there
and the
solution here has become cloudy, it's becoming hard to see
um... and that's just because there's so many bubbles in there primarily
and there is a little bit of a solid precipitate being formed there, I believe.
but, but mostly it's the bubbles. uh... The bubbles you see uh... are a gas being 0:01:51.150,0:01:52.640. given off, of course
And it turns out that the gas is hydrogen gas.
Uh... The movement is coming from the gas bubbles it is giving off and it's basically
like a little
uh...
motor on it, or a rocket on it, the little bubbles are pushing it around 0:02:26.419, 0:02:37.029 [garbled audio from speed up] 0:02:37.029, 0:02:38.689 there I'd say we're done
finally, there might be a little fleck left there
Next, quick we'll check back in on our magnesium.
still a whole lot of nothing going on.
Anyway, our next one is lithium,
and I'd like you to see how it is stored.
And then I'd like to point out that all the other are stored like this. Um...all the rest: lithium, sodium, potassium.
Uh...but I have it stored here inside a metal can, um..., and then inside that metal can is a whole bunch of kitty litter.
And, um..., that's to keep moisture from getting in there.
uh... and inside there, then, is a plastic bag,
and that's twist-tied shut,
and inside there
is a bottle,
and inside that bottle
you'll see a liquid.
You can see a liquid in there.
Um... And so, uh... and in that liquid you can see floating then
some dark bits, and those dark bits are our
lithium metal.
Get out a new watchglass here-
so that's our lithium metal.
And they've stored under all these precautions to try to keep it from
reacting with oxygen or
water vapor in the air. Even so you'll notice that the lithium is pretty dark.
in color- a covering of oxide on it.
But this metal here you'll notice
I can cut right through with a spoon-
dull edge of a spoon there.
and inside
you can see
a shiny metal.
Not that dull
dark outer surface
[cut/jump]... So, the reason that's there's an oxide coating on the outside.
we take this
and get down another water.
Again the gas being given off is actually hydrogen.
I can smell it.
It's not smoke it's uh... a water vapor convincing on the hydrogen gas being formed
The hydrogen gas being given off is quite
warm as it rises it cools, and as it cools it condenses some water vapor out of
the air. So it's not actually smoke but it is a
result of the reaction. And there is a gas being given off, at least.
That piece is almost done so we'll drop our other chunk in here.
That's the lithium.
This here's sodium, again it's got a dull coating on it- on its outer edge.
Sodium
I would say is even a little softer, a little easier to cut
And again you will notice,
that it is very shiny for a metal. But, it, but, I want you notice that I'm cutting
metals with a spoon. And I can squeeze pretty hard and squeeze
through this
pretty easily.
Uh, but we'll
shrink down the size of it a little bit.
and then we'll drop a piece of...
(uh...we'll take that one)
this into the water.
And, you'll notice immediately that it turns into a spherical shape
It's actually molten. -Oooh!
[crack/loud pop] -Aaahhh!!
You can see why I stepped away.
We'll try again here…
sodium metal.
-[cough]
-Now it doesn't always catch on fire, like it did there
but you can see uh...it's turned molten, and because it's molten it’s that little ball shape.
Uh...it's actually a molten metal there on the surface. There we have the fire. The fire is what color by-the-way? -[Audience]: Orange.
It's an orange flame. And, you're like, "Yeah, all fires are yellow-orange”, but the next one will be...uh...you might, might notice a different
color.
It doesn't always pop. -Dang it!
Got one more small piece here, we'll do, about the same size as the last two.
[sizzling noise]
There's the fire again.
But you'll notice: more reactive than lithium, more reactive than the alkaline [earth] metals we looked at
Anyway, one last one to show you, and that is potassium
Anyway, that there's potassium
And, again just to show you, it is a soft metal I can cut it with a knife.
Or with a spoon.
In fact I cut it, and accidentally flipped it
off the watch glass there. We can cut it with a spoon.
and we need to get down,
or use our last beaker of
water here.
So here we go, and...
It is a little [stuck], got to scrape it in.
-Whoa! -Whoa! -Color of the flame? -Pink? -Purple!
Kind of purpely color
Lavender color, is usually how it is described.
uh... but it is actually a, uh...
colored
flame that you are seeing.
Much faster reaction, yes it did catch on fire, and no it didn't pop like
sodium did.
But you'll notice that it was a...a fairly fast reaction, and that's again
because it's more reactive; and more reactive means not only the violence
of the reaction but also refers somewhat to the speed of the reaction, and so
you notice it's a much faster
reaction here.
... the demonstration.
Real quick here, one last time we'll check back on our magnesium.
Remember our magnesium we did way at the beginning?
If you look really close down at the magnesium, you'll notice it's floating now. And because it's floating now that means that it's somehow
become less dense that the water. And fact is, there's some bubbles on here. They're some very
tiny bubbles and
[beep of bell to end class] there I shook most of them off
And so, it does react, just very slowly.