Molecules

Molecule is a group of two or more than two atoms that helps to form smallest identifiable unit that are included in pure substance and can be divided in to many smaller parts. This helps in retaining the total composition as well as includes chemical properties of the particular substance.

The dividing of the sample of a particular substance in to many smaller parts helps in producing no change in their composition as well as no change in the chemical properties of the substance until the substance reaches to one molecule. The subdivision of the molecule of a particular substance in smaller parts usually are different from original substance in their composition stage as also differs in their chemical properties. In the later fragmentation stage, there are chemical bonds that helps to hold more atoms altogether in that molecule that is already broken.

The atoms mainly consist of a nucleus that are positively charge and is surrounded by cloud of electrons that are negatively charged. When the atoms reaches to some other atoms closely, the clod of electrons mainly interacts with other atoms and also reacts with the nuclei. If with this interaction, the total energy of a particular substance is lowered, then the atoms in those substance are bonded together that helps to form a molecule. From the structural view point, there is a molecule that consist aggregation of those atoms that together forms valence forces. The diatomic molecules mainly consists of two different atoms that are bonded chemically. If both the atoms in the molecule are same or identical, they together compose homo nuclear diatomic molecules. For example, the oxygen molecule composes with monoxide molecule together forms a hetero nuclear diatomic molecule. The molecules that contains one atom or more than two atoms are mainly termed as more than two atom and are commonly termed as the polyatomic molecules. Examples of polyatomic molecules are carbon di oxide, and water. The polymer molecules mainly consists of many thousands bonds for the component atoms.

The ratio of the total number of atoms that are associated with the atoms are bonded together that forms fixed molecules. Example of fixed molecules includes water molecules that contains two hydrogen atoms as well as contains one oxygen atom. This particular feature distinguishes all the chemical compounds from that particular solution and all other mechanical mixtures. This hydrogen as well as oxygen that are present in the molecules includes arbitrary proportions in the mechanical mixtures. So, it is stated that the proportions of hydrogen as well as the proportions of oxygen are present in different amount in mechanical mixtures. They makes a good combination with any proportions that forms chemical compound of water. Similar kinds of atoms are always possible to combine in different atoms and includes definite proportions that forms different molecules. This hydrogen atom will be bonded chemically with only one oxygen atom that forms the water molecule. It is also possible for all the atoms that helps in bonding together that forms identical proportions that forms different molecules of substance.   

The covalent compounds mainly consists of covalent bonds and these bonds mainly forms when the atoms in the molecules hare same electrons because they have same electro negatively values. The covalent compounds includes a diverse molecules group and has different exception rules.

General properties of molecules

1. Most of the covalent compounds have their melting point low and their boiling points is also low. The ions in ionic compound are attached strongly with other as because the covalent bonds can create molecules that are actually separated from each other. This is done mainly when an energy usually lower than the compound is added to the substance.

2. The covalent compounds mainly have low enthalpies of fusion as well as vaporization that has same ionic compounds. This enthalpy used in fusion is considered as the total amount of the energy that is needed at some constant pressure that helps to melt a mole of solid substance. Enthalpy of vaporization is known as the total amount of energy that is required for vaporizing a mole of liquid at some constant pressure. It is considered on an average that only 1% to 10% of heat is taken to change the molecular phase of the molecular compound which is done for the ionic compound.

3. The covalent compounds are tended to be soft and are relatively flexible. This covalent compound tends to be soft as well as are more flexible. This happens because the covalent bonds are flexible as are very easy to break the bonds. The total covalent bonds in all molecular compounds mainly causes compounds that are taken in the form of gasses, soft solids as well as liquids. There are also exceptions when the molecules are in the crystalline forms.

4. The covalent compounds have the tendency to be more inflammable compared to the ionic compounds. There are many inflammable compounds that contains hydrogen as well as carbon atoms that mainly undergoes the process of combustion. Combustion is a reaction that mainly releases energy when some compound reacts with the oxygen for producing carbon di oxide as well as water. The carbon as well as the hydrogen have comparable electro negative that can be found together in molecular compounds.

5. When molecules are dissolved in water, the covalent compounds does not conduct electricity through them. The property of ions are to conduct electricity that are present in the aqueous solution. The molecules compounds dissolve many molecules instead of having dissociating in ions. So, there is no conduction of electricity in the covalent bonds when they are mixed with water.

6. There are many covalent compounds that does not dissolve in water. As there are many exception like there are availability of many salts that does not dissolve in water, there are also many covalent bonds that also does not dissolve in water. The covalent compounds are the polar molecules that does not dissolve well in the polar solvents. Example might be considered as the sugar as well as ethanol.