JIKA ORANG LAIN BISA MENGAPA KITA TIDAK

Jumat, 30 November 2012

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AKlasifikasi Substances or Material
 

The material is composed of several constituent particles. Scientists classify a substance or material into two groups: single substances and mixtures. Elements and compounds are included in the class of a single substance. The element consists of metallic and non-metallic. Pure substances have properties that differentiate with other substances. For example, the element hydrogen are composed of hydrogen atoms only. Oxygen Elements are composed of atoms of oxygen alone. The behavior of oxygen and hydrogen do not appear on the substance formed from both, eg water (H2O). In nature there are 92 kinds of natural elements, while the rest are artificial elements. The total number of elements in the approximately 106 types of elements.

A. Element
 

The element is a single substance that can not be described again into other substances by ordinary chemical reactions. The number of elements present in nature is quite difficult for us to remember the name of the element. Therefore, we need a procedure to help us remember the name of the element. Jons Jacob Berzelius (1779 ~ 1848), introduced the procedure of writing the name and symbols of the elements, namely: (1) Each element is represented by a single letter taken from the initial letters of the name of the element. (2) Coat the elements written with capital letters. (3) For the element that has the same initial letter, then writing the distinguished name by adding one letter behind and lowercase. Example: Carbon Element written C, oxygen O written, written Aluminium Al, Ca Calcium written.

Grouping Elements
1) metallic element
 

Iron, copper, zinc, including metal
In general, the metal element has a characteristic shiny white, has a low melting point, it can conduct electricity, malleable and can conduct heat or hot. In general, metals are solid, but there is a metallic element that is liquid mercury. Some metallic elements that are useful in everyday life, such as:
a. Iron (Fe), is the most inexpensive metal, as a mixture with carbon produces steel for construction, automobiles and railways.
b. Copper (Cu), widely used in electrical wiring, jewelry, and coins. Copper alloy with tin produces bronze while producing a mixture of copper with zinc brass.
c. Zinc (Zn), can be used as the roof of the home, home appliances, and iron coatings to prevent rust.

2) non-metallic element
 

Examples of non-metals: Fluoride in toothpaste, iodine in iodized salt
In general, non-metallic elements have properties not shiny, poor conductors of electricity, and can not be forged. In general, non-metal is a poor conductor of heat, but there is a nonmetallic element that can conduct heat well which is graphite. Some non metallic elements that are useful in everyday life, such as:
a. Fluorine (F), when the fluoride compound mixed with toothpaste serves to strengthen the tooth, freon - 12 as a refrigerator and air conditioning refrigerant.
b. Bromine (Br), its benefits: bromine compounds are used as a nerve sedative, film photography, and mixed materials firefighting agent.
c. Iodine (I), the benefits are: iodine compound used as an antiseptic wound, extra iodine in salt, and as a test of starch (carbohydrates) in the flour industry.


3) semi-metallic element (Metaloid)
Elements of semi metals have properties between metals and non-metals. Some semi-metallic elements that are useful in everyday life, such as:
a. Silicon (Si), there are at most second nature after oxygen, ie 28% of the earth's crust. Silicone compounds are widely used in the cutting and sanding equipment, for semi conductors, as well as materials for making glass and ceramics.
b. Germanium (Ge), the presence of germanium in nature is very little, derived from coal and rock solid zinc. Germanium is a semiconductor material, which at low temperatures serves as an insulator, while at higher temperatures as a conductor.

B. Compound

Examples of compounds: water (H2O) and salt (NaCl)
The compound is a combination of several elements that are formed through chemical reactions. Compounds have properties that are different from their constituent elements. For example, two atoms of hydrogen with one atom of oxygen can combine to form a molecule of water (H2O). Hydrogen is a very light gas and combustible gas while oxygen is present in the air that our body is necessary for combustion. It seems clear that the properties of water vary with the nature of hydrogen and oxygen. Another example is a compound salt (NaCl). Salt prepared by the elements sodium and chlorine elements. Sodium has a light metallic properties, while chlorine is a toxic gas. The two elements are combined to form salt form of the mineral that is needed by our bodies. The compound includes a single substance that is composed of several elements with a fixed mass ratio. In nature there are about 10 million compounds. Water (H2O) is the most abundant compound in nature. Compounds are written in the form of a chemical formula. Its chemical formula is a substance that consists of a collection of items with the symbols of a particular composition. The composition is in the form of numbers which states the number of constituent atoms (index numbers). For example, a compound made up of atoms of the element sodium (Na) and the atoms of the element chlorine (Cl). If the index number of atoms of each element is 1 and 1, the chemical formula of compounds formed as follows:
The index number Na = 1, the index number Cl = 1,
So the chemical formula of the compound is NaCl (sodium chloride).
Formula may be the molecular formula and the empirical formula. The molecular formula is a chemical formula that states the type and number of atoms that make up matter. For example, C2H4 (Ethene), H2O (water). The empirical formula is a formula that states the smallest ratio of the number of atoms that form a compound. For example, the chemical formula C2H4, the empirical formula of the compound is CH2.


C. Mix
The mixture is a combination of a substance with no fixed ratio without going through a chemical reaction. In everyday life we
​​encounter many mixed. For example, river water, soil, air, food, water, salt solution, sugar solution, etc.. The original nature of the mixture forming substances exist that can still be distinguished from each other, some are indistinguishable. In the air mixed with some elements in the form of gas, such as: nitrogen, oxygen, carbon dioxide and other gases. Fresh air we breathe contains more oxygen than the air polluted. In the air is also composed of several compounds, such as: smoke and dust.
Mixed Grouping:
1. Homogeneous Mixture

Homogeneous Mixture Examples: Syrup
A mixture of two or more substances that the particles that are indistinguishable longer called a homogeneous mixture. Homogeneous mixture is often called a solution. Examples include: a mixture of water with the sugar called glucose solution, mix with salt water called brine. Size of particles in solution has a diameter of approximately 0.000000001 m, and can not be seen with a microscope. Stainless steel is an alloy of iron, chromium, and nickel. Gold is a homogeneous mixture, mixing metals is done by melting the metals. An alloy with other metals called alloys.

2. Heterogeneous Mixture

Heterogeneous Mixture Examples: river
A mixture of two or more kinds of substances whose constituent particles can still be distinguished from each other is called a heterogeneous mixture. Example of a heterogeneous mixture of soil, river water, food, beverages, sea water, cookie dough, batter concrete, etc.. In a heterogeneous mixture of substances between the wall can still be seen, such as water mixed with oil, a mixture of iron and sand, a mixture of iron powder and water, etc.. In the heterogeneous mixture divided into two parts, namely:
a. Colloid, the colloidal particles can only be seen with a microscope ultra. The particle size of between 0.5 m s.d 1 mm. Examples of colloids: milk, smoke, fog, agar-agar.
b. Suspension, the particles in suspension can only be seen with a regular microscope. Between particle size greater than 0.3 m. Example suspension: oil and water, murky water, and lime.

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