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DESCRIBING MOLECULES AND ATOMS

You need to learn how to describe simple chemical compounds and atomic structures. Here you have some examples and some pictures to practise. Be careful with the balls: the balls on the left column are atoms and the balls on the right column are particles inside the atoms (protons, neutrons, electrons)


Na2CO3
This compound has got three different elements: sodium, carbon and oxygen. There are two atoms of sodium, one atom of carbon and three atomos of oxygen.


This is an atomic structure. There five protons and five neutrons in the nucleus and there are five electrons moving around.
(The atomic number is seven. So, if you look at the periodic table, you will see this is the atomic structure of nitrogen)

This molecule has got two different elements and three atoms: one blue atom and two white atoms. (is a water molecule. It has got two different elements: the blue balls and the white balls. There are two white atoms and one blue atom.





When you look at the periodic table you can see lots of number and symbols (on the left).The most important number is the one writen in largest letters. That is the atomic number and is equal to the number of protons and the number of electrons.
For example, an atom of copper (Cu) has got 29 protons in its nucleus and 29 electrons moving around.
To know the number of neutrons is more difficult.

You can see all these pictures in these two presentations:
- Describing molecules.
- Describing atoms.
You can also visit this website.
 

Author: Pablo Acosta Robles