Calcium atoms have a nucleus in the middle (like other atoms do),
with 20 protons and 20 neutrons. Spinning around the nucleus are 20
really small electrons in 4 different orbits. The first orbit has 2
electrons in it, the next 2 have 8 each, and the outside orbit has the
last 2 electrons. It basically looks like this:
These pictures came from WebElements.com
They have a whole lot of information about everything about calcium you
can think of. You can find out about the history of calcium, different
things that have calcium in them, and ways that we use calcium. This is
just a little bit of the information that they have:
(The big problem with this picture is that it makes it look like
the electrons are bigger than the nucleus, but the nucleus is actually
a LOT bigger than any of the electrons.)
All the atoms in solid calcium are arranged in what's called 'cubic
closest packed structure,' with all of the atoms arranged as if they
were on the corners of perfect cubes. It basically looks like this,
where all the dots are the calcium atoms:
'Calcium is a metallic element, fifth in abundance in the earth's
crust, of which it forms more than 3%. It is an essential constituent
of leaves, bones, teeth, and shells.
The metal is a silvery colour and is rather hard. Chemically it
is one of the alkaline earth elements; it readily forms a white coating
of nitride in air, reacts with water, burns with a yellow-red flame,
forming largely the nitride. Calcium does not occur free in nature.
Calcium is found mostly as limestone, gypsum and fluorite. Stalagmites
and stalactites contain calcium carbonate.'
Hope this helps!
(republished on 07/19/06)