Excerpted from Wikipedia
Source: http://en.wikipedia.org/wiki/Chemistry
Date: 17-Nov-2014
Chemistry is a branch of physical science that studies the composition, structure, properties and change of matter. Chemistry is chiefly concerned with atoms and molecules and their interactions and transformations, for example, the properties of the chemical bonds formed between atoms to create chemical compounds. As such, chemistry studies the involvement of electrons and various forms of energy in photochemical reactions, oxidation-reduction reactions, changes in phases of matter, and separation of mixtures. Preparation and properties of complex substances, such as alloys, polymers, biological molecules, and pharmaceutical agents are considered in specialized fields of chemistry.
Chemistry is sometimes called the central science because it bridges other natural sciences like physics, geology and biology. Chemistry is a branch of physical science but distinct from physics.
The etymology of the word chemistry has been much disputed. The history of chemistry can be traced to certain practices, known as alchemy, which had been practiced for several millennia in various parts of the world.
Basic Principles of Chemistry
Every object is made of molecules.
Every molecule is made up of atoms.
Every atom is made up of quarks.
An atom is the same as an element.
There are 92 different naturally occuring elements.
Every atom is composed of a nucleus and an electron shell.
Every nucleus is made of one or more protons and zero or more neutrons.
What makes elements different is the number of protons in their nuclei. Hydrogen has one, helium has two, lithium has three, and so up to uranium, which has 92. The more protons an element has, the more massive and thus the heavier it is.
A compound is a substance that contains more than one kind of element.
An organic compound is one that contains the element carbon. Thus, oil, blood, steel and plastic are all examples of organic compounds.
Steel is an extremely strong compound composed of iron and carbon.
Silicon is an element. It is the primary component of beach sand, microprocessor chips, glass, and fiber optic cables.