CLASSIFICATION OF MATERIALS

CLASIFICATION OF MATERIALS

A.    Understanding Material Particles

The material particles are the smallest part of a material that still has the properties of the material. Particles can not be seen with the naked eye. There are three types of particle matter, namely: atoms, molecules and ions.

B.     Understanding Atom

Atoms are the smallest particles of an element. We simply describe an atom as a sphere, as Dalton described it. In contrast to Dalton who gives pictures to each ball, we can draw atoms as spheres of varying colors and sizes. The depiction of several types of atoms .

 

Scientists describe the shape of atoms in an atomic model. The atomic model was first proposed by John Dalton with his postulates as follows:

1.      Each material consists of the smallest particles called atoms.

2.      Atoms can not be subdivided into smaller parts.

3.      The atoms of one element are the same but different from the other elemental atoms.

4.       Compounds are matter consisting of two or more types of atoms of a certain ratio.

5.      The chemical reaction is the rearrangement of atoms.

The atom consists of an atomic nucleus and is surrounded by electrons moving in a particular orbit. Nearly all atomic masses are concentrated in atomic nuclei in the form of protons and neutrons. Understanding atomic and atomic symbols The symbol of an atom is written as follows:

 

A: mass number.

Z: atomic number.

Mass number                  : Number of protons + Number of neutrons.

Atomic number               : Number of protons  =  Number of electrons.

Number of neutrons         : Mass number - Atomic number.

C.     Understanding Elements

Element is a single substance that can not be decomposed into another element through ordinary chemical reactions. Some elements have their constituent particles of atoms arranged in the form of a particular crystal lattice. Elements that have atomic constituent particles are usually metal elements, such as iron, copper, zinc, aluminum and others. These atoms even form one crystal, but they stand alone. The metal element in the periodic table of elements is shown in green.

D.    Understanding Molecules

The molecule is a composite of two or more different or different atoms that form covalent bonds. Miscellaneous Molecules The molecule can be a molecular element and a molecule of a compound.

1.      Elemental Molecule

The element molecule is a molecule made up of similar atoms, the molecule is the smallest particles of an element. Elements of the smallest unit are molecules are non-metallic elements, such as sulfur, phosphorus, hydrogen, oxygen and so on. In the periodic system the non-metallic elements are shown in yellow.

The elemental molecule, which is a combination of two atoms, is called a diatomic molecule. Nonmetal elements that form diatomic molecules include hydrogen, chlorine, flour, iod, bromine.

2.      Compound Molecule

The compound molecule is a composite of two or more unlike atoms. Example of a compound molecule:

·         Water molecule (H2O) consisting of 2 hydrogen atoms and oxygen

·         The methane molecule (CH4) consists of 1 carbon atom and 4 hydrogen atoms

·         Acetic acid molecule (CH3COOH) combined from 2 carbon atoms, 4 hydrogen atoms and 2 oxygen atoms