Particle Matter 1

                                                 Atom

     Atom derives from Greek Atomos that means indivisible. The term atom was proposed by Greek philosopher, Leukippos and Democritus in 4th century BC. At that time there were two opinions about the division of matter, that is the opinion of Democritus and Aristotle.

a. Democritus

"The division of matter is discontinued. That is, if the material is divided and subdivided finally obtained the smallest particles called atoms."

b. Aristoteles

"The division of matter is continuous., Meaning that the division of matter can continue without limit."

     In 1803, an English physicisn and chemist, John Dalton, proposed a theory of atom Dalton's theory is concluded as follow :

1. Every material is composed of the smallest particel called atom.

2. Atom can't be subdivided to smaller particles with similar characteristic.

3. Atoms from certain element have the same characteristic and mass. Different elements have same atoms

    having different mass.

4.  A compound is composed of 2 or more different atom types.

5. Chemical reaction is the event of atom separation or incorporation from element or compound.

     Each atom consists of a nucleus and electrons orbit around the nucleus in certain paths called skin. The nucleus consists of protons (positively charged) and neutrons (Neutral). The negatively charged electrons.

1.Atom Model

  a. Rutherford model of the atom
      Describing the atom as a miniature solar system with electrons as the planets move around the nucleus.

b. Bohr model of the atom
      Describing the stability of electron moving in its orbit.

c. Schrodinger atomic model
     Draw where the probability of finding an electron is called an orbital.

2. Subatom Particles

 a. Proton
      Proton (p) are positively charged particles contained in the nucleus. The mass of a proton is 1 amu (atomic mass unit) and +1 charges are comparable to 1.602 x 10^-19 C (coloumb). Located in the nucleus and was discovered by Rutherford. According to Rutherford, "the atoms have a positively charged nucleus surrounded by electrons are negatively charged."
b. Neutron
      Neutron (n) does not have a charge or neutral. It has a mass of 1 amu. Located in the nucleus and was discovered by JJ. Thompson.

c. Electron
       Electron (e) is a subatomic particle with a mass of the lightest and has a charge equal to 1.602 x 10^-19 C (coloumb) negatively charged. Electron was discovered by J. Chadwick. Electrons surround the nucleus in their courses called shell or orbital. Atom is not charged if the protons and electrons in an atom is always the same.

Netral Atom Model

3. Atom Shell

     An atom has neucleus that circumference around by electrons. Electron spinning around necleus follows certain orbit that establishes atom shell.

Information:
1. The first orbit that is nearest with nucleus is occupied by two electrons, this orbit called shell K.
2. The second orbit is occupied by maximum 8 electrons, called shell L.
3.The third orbit is occupied by 18 electrons, called shell M.
4. The fourth orbit could accomodate 32 electrons at most, called shell N.
5. The fifth orbit could accomodate 32 electrons at most, called shell O.
6. The sixth orbit is etimated accomodate 18 electrons, called shell P.
7. The seventh orbit accomodate 2 electrons, called shell Q.

     Electrons orbit isn't always in circle shape, but also in ellipse. The orbit isn't  in flat surface but within space. The follows are example af atom model. 
a. Natrium atom

Natrium atom has 11 electrons. The valence is 1.

 Na atom has 11 electrons. K shell has 2 electrons, L has 8 electrons, and shell N has 1 atom or also called valence electron (eletron remaining).











4. Atom Number and Atom Mass Number