Molecules and atoms

Science DenNorske December 9, 2016 4 17
Everything is made of molecules. Molecules are the building blocks of substances. In this article the basis of the molecular and atomic theory is explained.


A molecule is the smallest particle that still has the properties of a substance. So pure water consists only of water molecules. In theory, so you can subdivide a glass of pure water molecules, but that's impossible. These molecules are very small. The size of molecules is expressed in terms of nanometers, one nanometer is equal to one billionth of a meter.


Molecules are in their turn subdivided into smaller particles: atoms. For example, a water molecule is made up of two hydrogen atoms and an oxygen atom. There are about 100 species of atoms. An atom contains a particular element. So you have the element hydrogen that is inside a hydrogen atom is.

Molecular formulas

As already told are molecules made up of atoms. In order to indicate from which a molecule is built up there are molecular formulas. A molecular formula indicates which and how many atoms there are in a molecule of a substance. Take the example of a water molecule, which has the molecular formula H2O. The letters in the formula to indicate the atoms which are in the water molecule. In water are two kinds of atoms, H for hydrogen and O for oxygen. Because there are two hydrogen atoms in a molecule are water, there is a little to the right under the two punch H.
Below are some molecular formulas with substance it:
  • Carbon dioxide CO2
  • Glucose: C6H12O6

The above compounds are only made up of C, O and H atoms. And because there are about 100 types of atoms, so there are billions of types of molecules.

Compounds and chemical reactions

If you look at a water molecule you can see that it consists of two types of atoms. Using special methods can we get water molecules apart and divide into H and O atoms. A molecule that we can take apart, so for example water, is called a connection.
What is above is actually not quite true. If a molecule is taken out of each other, which is called a chemical reaction, it can not be divided into single atoms. The atoms that come from a chemical reaction, always form new molecules. For example, the atoms from water would be divided into hydrogen molecules and oxygen molecules. Note that water and hydrogen are different things.

Phase change

The phase in which a substance will be divided into a few types: solid, liquid and gas. When water freezes it becomes solid, as it thaws again becomes liquid. During the boiling of the water evaporates, it becomes gas. Note that phase change is not a chemical reaction, the molecular formula of a substance does not change when the phase changes. 2 = di diodat is not in my chemistry boek😎