Physics "Element, Compound and Mixtures"

     Element

An element is single matter that cannot be broken into another matter by chemical or physical reaction. There are 110 elements on “element periodic table” Among the 110 elements below, 92 elements are natural elements and 18 elements are synthetics elements. Pure substance that cannot be separated into simpler substance by physical or chemical means.

1. Charateristics of Elements

      1.1      Consists of only one kind of atom.

      1.2     Cannot be broken down into simpler type of matter by either                       physical or chemical reaction.

      1.3     Can exist as solid, liquid gas.

2.  Symbol of elements

    2.1     Examples symbol of elements using one capital letter plus one small               letter. Helium (He), Magnesium (Mg), Neon (Ne), Lithium (Li).

      2.2     The symbol of element consists of one capital letter or one capital                letter plus one small letter.

      2.3     To help you remember and write chemical compound, in 1813 Jons                  Jacob Berzelius proposed alphabets as the symbols each element.

      2.4     Examples symbol of element using one capital letter :

               Hydrogen (H), Carbon (C), Oxygen (O), Nitrogen (N).

     Compound

A single matter consists of more than one element, which can be broken down into simpler by chemical reaction. Pure substance composed of two or more different elements joined by chemical bonds. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together in a defined spatial arrangement by chemical bonds. Chemical compounds can be molecular compounds held together by covalent bonds, salts held together by ionic bonds, intermetallic compounds held together by metallic bonds, or complexes held together by coordinate covalent bonds. Pure chemical elements are not considered chemical compounds, even if they consist of molecules that contain only multiple atoms of a single element (such as H2, S8, etc.),  which are called diatomic molecules or polyatomic molecules. hemists describe compounds using formulas in various formats. For compounds that exist as molecules, the formula for the molecular unit is shown. For polymeric materials, such as minerals and many metal oxides, the empirical formula is normally given, e.g. NaCl for table salt.

Example :

     A water molecule is an example of a chemical compound, consisting of two parts hydrogen and one part oxygen.

1. Charateristics of Compound.

   1.1      Consist of more than one element.

Examples : Carbon dioxide (CO₂), Ammonia (NH_­3­) acetate acid                              (CH ₃COOH).

          1.2     Can be broken down into simpler matter by chemical reaction.

Water can be broken into hydrogen and oxygen (Water is made up      of hydrogen and oxygen).      

Sugar can be broken into carbon, hydrogen ang oxygen (sugar is                    made up of carbon, hydrogen and oxygen).

     1.3     The properties of compound is totally different with the                                   properties of each element which composed it.                         

Example : The properties of sugar is different with the properties                   of carbon ( carbon is black solid), hydrogen and oxygen                        are flammable gas.

          1.4     Elements in a compound are present in a definite proportion

Example- 2 atoms of hydrogen + 1 atom of oxygen becomes 1 molecule of compound-water. Elements that comprise a compound do not retain their original properties.

For example, hydrogen (combustible and non-supportive of combustion) + oxygen (non-combustible and supportive of combustion) becomes water (non-combustible and non-supportive of combustion). Valency is the number of hydrogen atoms that can combine with one atom of the element to form a compound.

          1.5     The comparation of the mass of element in compound is fixed.

2. Separating compound

              Compound is single matter that can not be broken down by physical               separation. But, compound can be broken down into its elements by               a chemical reaction.

                   Example :

Ø  Sucrose has chemical formula C₁₂H₂₂O_11.

Ø  The chemical formula also shows that, one molecule of sucrose consist of 12 atoms of carbon, 22 atoms of hydrogen and 11 atom of oxygen.

Ø  Its means that, sucrose is made up by carbon, hydrogen, and oxygen.

        Mixture

Mixture is a combination of some substance without chemical reaction. A mixture refers to the physical combination of two or more substances on which the identities are retained and are mixed in the form of alloys, solutions, suspensions, and colloids. Substances held together by physical forces, not chemical ,No chemical change takes place. Each item retains its properties in the mixture,they can be separated physically.

1. Mixtures

   Divided into Homogenous and Heterogeneous mixtures.

              1.1. Homogenous Mixtures

·      A mixtures that has two or more components mixing well is called homogenous mixtures.

·      All solutions are homogenous.

·      Examples of solution : salt solution, sugar solution, paint, milk.

1.2. Heterogeneous Mixtures.

·      A mixtures that can be separated into its forming components is called heterogenerous mixtures.

·      Example      : soil, granite stone, blood.