Chemistry

Matter: Matter can be classified as a solid, liquid, gas, or plasma: Solids: have definitive volumes and shapes. Liquids: have distinct volumes, but their shape depends on the container they are contained within. Gases: have no fixed volume or shape; they assume the shape of the container they are in.  Note: Gases are highly compressible while liquids and solids aren't. Matter can also be classified according to its composition:  Atoms: The building blocks of all matter. Elements: Made from the same kind of atoms. An element can't be decomposed into simpler substances by chemical means. Pure substance: Matter that has distinct properties and a composition that doesn't vary from sample to sample. A pure substance can either be an element or a compound. Very few pure substances exist in our natural environment. Compounds: Made up of 2 or more different kinds of atoms. Compounds can be broken down into simpler substances by chemical means but not by...

Dalton's Atomic Theory: Some basic laws that have been established by the year 1800: Law of definite composition (Berzelius):  Every pure compound has a constant composition. Laws of conservation of mass (Lavoisier):  Matter can neither be created or destroyed during a chemical change. Dalton's Laws: All matter is composed of extremely small particles called atoms. All atoms of a given element are alike, but atoms of one element differ from atoms of any other element. Compounds are formed when atoms of different elements combine in fixed proportion. A chemical reaction involves a rearrangement of atoms. No atoms are created or destroyed or broken apart in a chemical reaction. The law of definite composition is explained by the third statement. Water (H 2 0) is always formed by two atoms of hydrogen joining with one atom of oxygen. Its elemental composition never changes, no matter were it was from or how it was synthesised.  The fact that chemical ch...