CHEMICAL FORMULA

FORMULA

The  atomic composition of a water molecule can be decribed either 

in words , i.e.
'Each molecule of water contains two atoms of hydrogen and one atom of  oxygen chemically combined together.
or 
by its chemical formula, i.e.

                                    H2O
Obviously, the chemical formula is a smaller method of  showing the atomic composition of the water molecule.
The CHEMICAL FORMULA of a molecule shows the number and kinds of atoms contained in it. The chemical formula of a molecule of an element is denoted by the chemical symbol of the element and a subscript showing the number of atoms in the molecule. For example, H2 denotes a molecule of hydrogen which consists of two hydrogen atoms.

 The same method  is used in representing the chemical formulae of compounds. There are at least two chemical symbols in the chemical formula  of a compound because each molecule of a compound is made up of two or more different types of atoms. When more than one atom of an element is present, the number of atoms is given by a subscript. When no subscript is written, we assume that the number of atom is one.

MOLECULES

What is a Molecule?

A molecule is made up of two or more atoms of the same kind or of different kinds chemically combined together. Molecules exist in both elements and compounds. Molecules in elements consist of  a fixed number of one kind  of atom only. For example, each molecule of hydrogen  gas is made up of two hydrogen atoms combined chemically together. Many of such hydrogen molecules make up hydrogen gas. Each molecule of  gaseous elements such as oxygen, chlorine and nitrogen are also made up of two atoms. In some cases, three identical atoms may combine to form a molecule, as in the ozone molecule which is made up of three oxygen atoms.

 

Hydrogen molecule                                                   

Molecules  in compounds consist  of a fixed number of two or more different  kinds of  atoms  chemically combined  together. A carbon monoxide molecule is made up of  one carbon and one oxygen atom. A water molecule consists of two  hydrogen atoms  and one oxygen atom. A glucose  molecule consists of  six carbon atoms, twelve hydrogen atoms and six oxygen atoms.

Carbon monoxide molecule                          Water Molecule

 

ATOMS

Representing Atoms

Circles are commonly used to represent atoms. The symbols below represent the atoms of  some elements.

Another way of representing different kinds of  atoms is by using spheres of various size and colours. These  spheres are normally held together  by sticks or springs in an arrangement similar to that of atoms found in a substance. The model below use spheres to show the arrangement of  carbon atoms in diamonds.                                                                                          Representing of atoms using models and diagrams makes it easy to understand science.                           

ATOMS AND MOLECULES

What is an Atom?

For many years, people  have wondered what matter is made up of. Some ancient Greek  philosophers believed  that all matter was made up of four substances, namely earth, water, air and fire. Ancient Chinese philosophers believed that matter was made up of  gold, wood, water, fire and earth. About 430 B.C., a Greek philosopher named Democritus suggested that  matter was made up of  indivisible particles called atoms. This came from the Greek word 'atomos' , meaning 'indivisible'. He believed that nothing could be smaller than an atom.

An atom is defined as the smallest existing particle. They are the building blocks of  all matter.

All matter, living or non-living, is made up of atoms. Atoms are so small that you cannot see them with an  ordinary microscope. It can only be seen through a special microscope. A single atom measures only about  1/10 000 000 mm across. More than 10 000 000 000 000 (ten trillion) atoms would  be needed to cover the full stop at the end of this sentence.

Each element is made up of its own type of atom. Carbon is made up of  its identical carbon atoms, same as this iron is made up of iron atoms. The atoms of different chemicals are not of the same size.

SCIENCE

WHAT IS SCIENCE?

Science is the systematic study of nature and how it affects us and the environment. It is the knowledge which is changing rapidly for more accuracy and new change about that information. Technology is the way in which science is used to build machines to make our life more comfortable and much more easier.
                                                                                                                                       

                                                                                              

 

 Science Facts

  Science is divided into  different branches.     

  Biology:the study of living things.

  Chemistry:the study of  substances.

 Physics:the study of  matter,energy and natural forces.

 Astronomy:the study of solar  system and outer space.    

Geology:the study of Earth.