# Practical Electronics/Atoms structure
## Matter

Matter refers to any physical quantity that can be measured and has its own physical and chemical properties.

### Physical Properties

All matter exists in one of three states, called the classical States. They are: solid such as an ice cube, liquid such as water and gas such as water vapour.
All matter has mass, volume and density. Density is equal to the ratio of mass over volume.
    $D={\frac {M}{V}}$
where
    M, Mass measured in Kilogram kg
    V, Volume measured in m$^3$
    D, Density measured in Kilogram kg/m$^3$

### Chemical Properties

All matters are made up of one or more chemical Elements.
Each chemical element is made up of atoms. An atom is the smallest part that makes up an element.
As of 10 April 2010, there 118 confirmed chemical elements known to mankind , organised in what is known as the periodic table, which lists each elements chemical symbol, atomic number and atomic mass.
    m
       E
    z
Where
    m, Mass
    E, Element
    z, Atomic number

### Sub Atomic Electric Charged Particles

Further study of matter has shown that atoms are made up of sub-atomic particles that carry electric charge. There are three kinds of charged particles, as far we're concerned here.
* Electron
    Electrons carry negative charge has a symbol e$^-$ and a mass of 0.005 a.m.u
* Proton
    Proton carries positive charge has a symbol p$^+$ and a mass of 1 a.m.u
* Neutron
    Neutron carries no charge has a symbol n$^0$ and a mass of 1 a.m.u
Nucleus are formed by combining protons and neutrons together but they could not carry electrical charges. In spite of the neutron's no charge , it is attracted to protons when it is bonded closely together.

#### Rutherford's Model

In 1911, Rutherford propose a model of matter consisting of charged particles such as Electron , Proton and Neutron. Due to advance technology and understanding of the science today have advance, Rutherford's model are not considered anymore as accurate representation of atoms.
According to Rutherford's model,
* All matter has a Mass M a Volume V and a Density equals to the ratio of Mass over Volume exist in one three states Solid like Ice cube, Liquid like Water , Gas like Water vapor
* An atom consists mainly empty space with electrons orbiting a fixed, positively charged nucleus in set, predictable paths.
* All matter made up from Charged Particles the smallest indivisible part still has matter's characteristics
* All matter has a Nucleus made of Proton and Neutron in the center and Electron's orbits circulating around the Nucleus
* Number of electrons in the orbits must be equal to number of protons in the nucleus . Atomic number in the Periodic Table indicates number of Protons in the nucleus or the number of electrons in orbits.
* Only Electron in the outermost orbit can participate in reaction
* The size of the nucleus of an atom is very small in comparison to the total size of an atom.

#### Bohr's Model

In 1913, Bohr proposed that
* Each electron's orbit has a quanta of energy correspond to an Energy Level Number n .
* There are 4 Energy Level Number n = 1 ..4 . n = 4 has the highest energy level . n = 1 has the lowest energy level
* The energy level is depending to the size of orbit, the smaller orbit, the smaller energy level it is
* When electron moves from High Energy Level to Low Energy Level Electron will emits Electromagnetic Light Wave
* E$_{n-1}$ - E$_n$ = hf