Monday, 28 November 2016

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Particulate Nature of Matter; Atoms, Molecules and ions

nature of matter

Matter is made up of discrete particles the main ones being atoms, molecules and ions.

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An atom is the smallest particle of an element which can take part in a chemical reaction. An atom can also be said to be the smallest particle of an element that can ever exist and still possess the chemical properties of that element.

Most atoms cannot exist alone. They generally bond with other atoms to form molecules. Therefore, atoms can be made up of atoms of either the same elements or different elements.
     The number of atoms in each element is called Atomicity of the element.
Most gaseous elements such as chlorine, hydrogen, oxygen, nitrogen etc., are DIATOMIC (Molecules with one atom)
Some elements may be MONO ATOMIC (Molecules with one atom); for example, noble gases (Argon (Ar), helium (He), Neon (Ne))
TRIATOMIC molecules (Molecules with three atom), for example; ozone (O3).
POLYATOMIC molecules (Molecules with three atom), for example; phosphorous, Sulphur.

Atomicity of some molecular elements
ELEMENT                                      FORMULAE                ATOMICITY
Neon                                                 Ne                              1
Argon                                                Ar                              1
Helium                                             He                              1
Hydrogen                                         H2                              2
Nitrogen                                           N2                              2              
Oxygen                                             O2                              2
Chlorine                                           CL2                                   2
Bromine                                           Br2                                   2
Phosphorous                                    p4                                    4
Ozone                                                O3                               3
Sulphur                                              S8                                    8

Note: A molecule can be defined as the smallest particle of a substance that can normally exist alone and still retain the chemical properties of that substance be it an element or a compound.

An ion is formed when an element loses or gains electrons. It carries a positive charge when electrons are lost and negative charge when electrons are gained.
     However, an atomic substance is said to be electrically neutral when it has the same number of positive and negative ions. That is, it has no charge.

Note: An ion can also be defined as any atom or group of atoms which possesses an electric charge. Examples are, NH4+, Ca2+ ,Cu2+ ,O2-, SO42-, SO32- , OH- , Na+  etc.

Previous article emphasised more on the concept of matter, examples and phases of matter. This study on the particulate nature of matter is an introduction for easy understanding and assimilation.

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