1. A molecule is a group of at least two atoms chemically combined in definite
proportions.
For example, a water molecule (H2O) is always composed of two atoms of hydrogen chemically combined with one of oxygen. (a 2 hydrogen :1 oxygen proportion)
If you have a combination of three hydrogen atoms with one oxygen atom
(3 hydrogen:1 oxygen ) , the combination is notwater;this is what is meant by defininte proportions.
2. Molecules are held together by covalent bonds;i.e., the sharing of pairs of electrons holds the atoms together. Also, molecules are held together by columbic forces or forces of electrostatic attraction in case of ionic compounds.
Additional Note : * If different kinds of atoms combine to form a molecule, the
substance formed is called a compound.
An example of a compound is water.
* If atoms of the same kind combine to form a molecule, the substance is
called an element.
Example , oxygen (O2)
A disaccharide is formed by one molecule of Galactose and one molecule of Glucose bonded together...
a water molecule is also formed (a.k.a. H2O)
A compound (a molecule) is formed.
the guru molecule is formed by amino acids
This molecule is ammonia - NH3.
the guru molecule is formed by amino acids
lactose
When NAD is reduced, the resulting molecule formed is NADH.
A disaccharide is formed by one molecule of Galactose and one molecule of Glucose bonded together...
Sodium chloride is formed. Its formula is NaCl.
A compound (a molecule) is formed.
when a phosphate group is removed from ATP energy is released and the molecule ADP is formed.
cellulose
An element is formed from atoms; atoms are formed from protons, neutrons and electrons.Protons and neutroms are formed from quarks and gluons.A molecule is formed fro atoms.
protein
a water molecule is also formed (a.k.a. H2O)
Ozone is a tri oxygen molecule. It is formed in a natural process by the action of UV light on oxygen molecule.