Chemical Reactions

1. Periodic Table The periodic table is a chart that has information about all the elements, molecules and atoms. It has metals, non-metals and metalloids. It uses short form to identify the chemicals.

2. Elements and Atoms An element is made up by atoms which is distinguished by its atomic number. Which is the number of protons and nucleus. Common examples of elements are iron, copper, silver, gold, hydrogen, carbon, nitrogen, and oxygen. 80 elements occur naturally on earth and there are 117 that are on earth.

3. Compounds A compound is a chemical substance made of two or more different chemical elements. 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. Water is a compound made up of hydrogen and oxygen.

4. Metals and Non-Metals Metals are high conductors of electricity and heat. Metals usually have 2-3 electrons in their outer shells. Non-metals usually have 4-8 electrons in their outer shell. They are also bad conductors of heat and electricity.

5. Chemical Reactions A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Chemical reactions can either be spontaneous or only happened when exposed to light, heat or electricity.

6. Chemical and Physical Chemical Changes: Chemical changes take place on the molecular level. A chemical change produces a new substance. Examples of chemical changes include combustion (burning). Physical: Physical changes are concerned with energy and states of matter. A physical change does not produce a new substance. Changes in state or phase melting, freezing, vaporization, condensation, sublimation.