Molecules

Molecules always in Motion.When more than two atom share electron then molecule formed. A molecule represents the chemical properties of that chemical element or Compound. For Example ,Water H2O is a compound, there is two Atom of Hydrogen and One Atom of Oxygen. A water molecule describe the properties of water.

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Law of Mass Action (equilibrium)

law of mass action:

law stating that the rate of any chemical reaction is proportional to the product of the masses of the reacting substances, with each mass raised to a power equal to the coefficient that occurs in the chemical equation. This law was useful for obtaining the correct equilibrium equation for a reaction, but the rate expressions it provides are now known to apply only to elementary reactions.

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Properties of Matter

Dictionary definitions of chemistry usually include the terms matter,composition, and properties, as in the statement that chemistry is the science that deals with the composition and properties of matter.Matter is anything that occupies space and displays the properties of mass
and inertia. Every human being is a collection of matter. We all occupy space,and we describe our mass in terms of weight, a related property.All the objects that we see around us consist of matter.The gases of the atmosphere, even though they are invisible, are matter they occupy space and have mass. Sunlight is not matter; rather, it is a form of energy.Composition refers to the parts or components of a sample of matter
and their relative proportions. Ordinary water is made up of two simpler substances hydrogen and oxygen present in certain fixed proportions.A chemist would say that the composition of water is 11.19% hydrogen and 88.81% oxygen by mass. Hydrogen peroxide, a substance used in bleaches and antiseptics, is also made up of hydrogen and oxygen, but it has a different composition. Hydrogen peroxide is 5.93% hydrogen and 94.07% oxygen by mass.Properties are those qualities or attributes that we can use to distinguish one
sample of matter from others; and, as we consider next, the properties of matter are generally grouped into two broad categories: physical and chemical.
Physical Properties and Physical Changes
A physical property is one that a sample of matter displays without changing its composition. Thus, we can distinguish between the reddish brown solid,copper, and the yellow solid, sulfur, by the physical property of color .Another physical property of copper is that it can be hammered into a thin sheet of foil. Solids having this ability are said to be malleable.Sulfur is not malleable. If we strike a chunk of sulfur with a hammer, it crumbles into a powder. Sulfur is brittle. Another physical property of copper that sulfur does not share is the ability to be drawn into a fine wire (ductility). Also,sulfur is a far poorer conductor of heat and electricity than is copper.Sometimes a sample of matter undergoes a change in its physical appearance.In such a physical change, some of the physical properties of the sample may change, but its composition remains unchanged. When liquid water freezes into solid water (ice), it certainly looks different and, in many ways, it is different. Yet, the water remains 11.19% hydrogen and 88.81% oxygen by mass.
Chemical Properties and Chemical Changes
In a chemical change, or chemical reaction, one or more kinds of matter are converted to new kinds of matter with different compositions. The key to identifying chemical change, then, comes in observing a change in composition. The burning of paper involves a chemical change. Paper is a complex material,
but its principal constituents are carbon, hydrogen, and oxygen. The chief products of the combustion are two gases, one consisting of carbon and oxygen (carbon dioxide) and the other consisting of hydrogen and oxygen (water, as steam). The ability of paper to burn is an example of a chemical property. A chemical property is the ability (or inability) of a sample of matter to undergo
a change in composition under stated conditions

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Mole of Molecules

Mole of Molecules:
The mass of a mole of molecules of a substance is the molecular mass expressed in grams.  For
example, an oxygen molecule (O2) has a molecular mass equivalent to 32.0 grams because each oxygen atom has a molecular mass of 16.0 grams.

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The Mole

The Mole:
A single atom or a few atoms are rarely encountered.  Instead, larger, macroscopic quantities
are used to quantify or measure collections of atoms or molecules, such as a glass of water, a
gallon of alcohol, or two aspirin.  Chemists have introduced a large unit of matter, the mole, to
deal with macroscopic samples of matter. 
One mole represents a definite number of objects, substances, or particles. For example, a mole
of atoms, a mole of ions, a mole of molecules. A mole is defined as the quantity of a pure substance that contains 6.022 x 10^23 units of that substance.  In other words, a mole is Avogadro's number of anything.

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Molecules(Molecules of an Element and Molecules of a Compound)

Molecules
Molecules are groups or clusters of atoms held together by means of chemical bonding.  There
are two types of molecule; molecules of an element and molecules of a compound.

1. Molecules of an Element                                                                                                                  In certain cases, two single atoms of an element can be attracted to one another by a bond to form a molecule.  Examples of this are hydrogen, oxygen, and bromine.
2. Molecules of a Compound                                                                                                        Two atoms of different elements held together by a bond form a compound.  The molecule is the primary particle of a chemical compound. Some examples of this type of molecule include hydrogen chloride , water , methane andammonia .

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Atomic Mass Number

The sum of the total number of protons, Z, and the total number of neutrons, N, is called
the atomic mass number. The symbol is A.  Not all atoms of the same element have the
same atomic mass number, because, although the Z is the same, the N and thus the A are
different.  Atoms of the same element with different atomic mass numbers are called
isotopes.

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Atomic Number

The number of protons in the nucleus plays such an important role in identifying the
atom that it is given a special name, the atomic number. The symbol Z is often used for
atomic number. Hydrogen has an atomic number of 1 and
lawrencium has an atomic number of 103.  The atomic number is also equal to the
number of electrons

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Atom (The atom structure)

An atom is composed of a positively-charged nucleus orbited by one or more negatively-charged
particles called electrons.The neutrons are electrically neutral, and the protons are electrically
positive. Together the neutrons and protons give the nucleus its mass.The particles that orbit the nucleus are electrons. Each electron is negatively charged, and the charge of one electron is equal in magnitude (but opposite in sign) to the charge of one proton. Each electron is negatively charged, and the charge of one
electron is equal in magnitude (but opposite in sign) to the charge of one proton. 

 An atom is an extremely small electrically-neutral particle. An atom is composed of a positively-charged nucleus orbited by one or more negatively-charged
particles called electrons.
The diameter of the atom is determined by the range of the electrons in their travels around the
nucleus and is approximately 10 ^-8 cm.  The diameter of the nucleus is roughly 10,000 times smaller, approximately 10^-13 to 10^-12 cm.  Because the nucleus is composed of neutrons and
protons that are about 1835 times heavier than an electron, the nucleus contains practically all
the mass of the atom, but constitutes a very small fraction of the volume.  Although electrons
are individually very small, the space in which they orbit the nucleus constitutes the largest part
of the atomic volume.

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Characteristics of Matter

The term states of matter refers to the physical forms in which matter exists:  solid, liquid, and
gas. Solids are characterized as having both a definite shape and a definite volume.  In a solid,
the forces that keep the molecules or atoms together are strong. Therefore, a solid does not
require outside support to maintain its shape.
Liquids have definite volumes but indefinite shapes and are slightly compressible.  Liquids take
the shape of their containers.  The forces that keep a liquid's molecules or atoms together are
weaker than in the solids.
Gases are readily compressible and capable of infinite expansion. They have indefinite shape and
indefinite volume.  Of the three states, gases have the weakest forces holding their molecules or
atoms together.
The different states of matter have one thing in common; they can all be broken down into
fundamental units called atoms.

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Branches Of Chemistry

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1. Organic Chemistry
2. Inorganic Chemistry
3. Physical Chemistry
4. Biochemistry
5. Analytical Chemistry
6. Nuclear Chemistry
7. Organic Chemistry
8. Inorganic Chemistry 

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History of Chemistry

The earliest record of man's interest in chemistry was approximately 3,000 B.C, in the fertile crescent. At that time, chemistry was more an art than a science. Tablets record the first known chemists as women who manufactured perfumes from various substances. Ancient Egyptians produced certain compounds such as those used in mummification. By 1000 B.C, chemical arts included the smelting of metals and the making of drugs, dyes, iron, and bronze. Iron making was also introduced and refinement of lead and mercury was performed. The physical properties of some metals such as copper, zinc, silver, and gold were understood. Many groups of people contributed to these developments--among them were ancient Egyptians, Greeks, Hebrews, Chinese, and Indians.
                                                                                              [the above paragraph from www.albalagh.net]

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Chemistry

Chemistry                                                                                                          (9th to 10th level)
What is Chemistry?

seratpedia

Chemistry the branch of science that deals with the composition, structure, properties and reactions of matter, is called chemistry.
Explanation
Chemistry is concerned with atoms  and particularly with the properties of chemical bonds^.
Chemistry is called "the central science" because it connects with other science subjects.
like that ,Biology, physic and geology.
In chemistry we can study elementary particles, atoms, molecules, substances, metals, crystals  

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