The planet Earth....... how did this ever happen?
one of the magical things about the third rock from the Sun is the presence of liquid water
liquid water....water... the planet Earth is all about water let's take a good look at water
Water consists of two oxygens and a hydrogen (?) let's look at the oxygen
oxygen has six extra electrons... two of the electrons are tied up with the extra electron in hydrogen
so that's two down and the other two (4) stick out the back in these big clouds
and,,, so a molecule of water is a triangle.... it's a triangle
but if you include the clouds, which you really have to do, the oxygen molecule becomes a tetrahedron
with the clouds sticking out the back.. so there's the water molecule as a triangle
but there is these two big clouds that point out in a perpendicular plane
to the plane of the molecule itself
the behavior of water is all about hydrogen bonding
hydrogen bonding is a structural..... a very specific structural technique (feature) in biochemistry
the strands of DNA are held together with hydrogen bonds and,
in DNA, the bonds work together because of the geometry of the molecule
which is to say the geometry of the nucleic acid bases themselves
in water, the hydrogen bonds are the same thing but they don't have that structure behind them
and the result of it, is that the hydrogen bonds....
they don't have anything... .. they don't do anything really specific
the hydrogen bond works like this
the hydrogen... this is the hydrogen ...the hydrogen interacts with the clouds
with the two clouds and there are two of them so that every oxygen molecule
can interact with two through its hydrogen and two through its clouds
the result of all this is that a water molecule can have a weak interaction with four other water molecules
so it's as if the water molecules are all
they're all sort of loosely knitted together
the hydrogen bonds are very weak ....very very weak but the thing is.. there are so many of them in water
water is just massively hydrogen bonded to itself
and the hydrogen bonds are weak but there's a lot of them
I want to point out three aspects of this
one of them is that water has high surface tension
on the surface of the water, the water tends to stick to itself and not to other things
and the result of this is that you can float a paper clip on a glass of water
(a) water striders is an insect that lives on water
the water strider walks on the water using the surface tension
water has a heat of vaporization,, high heat capacity and a high enthalpy of fusion
this means that water is a great conductor of heat
is liquid over a large range of temperatures
and that ice is great for cooling down drinks
which is to say that ice ....it takes a lot of heat to make the ice back into liquid
and that can be used to cool down soft drinks
and 800 million years later, here we are
Let's do an experiment
to do the experiment we need... an eyedropper, ....a coin
in America, I think of a coin as being a penny, but it could be any kind of coin.
and some water
the question would be: ask yourself "how many drops of water can I fit on a coin? "
how many drops water will fit on the coin? Try it!
and that's it and thanks