An element is a material that consists of a single type of atom. Each atom type contains the same number of protons. Chemical bonds link elements together to form more complex molecules called compounds. A compound consists of two or more types of elements held together by covalent or ionic bonds.

The periodic table, also known as the periodic table of elements, is a tabular display of the chemical elements, which are arranged by atomic number, electron configuration, and recurring chemical properties. The structure of the table shows periodic trends.

All elements have certain characteristics that are summarized on the periodic table. These characteristics include the element’s symbol, atomic number, and atomic mass. You will learn how the number of protons in an atom relates to an element’s atomic number, and explore how isotopes affect the atomic mass.

The four elements common to all living organisms are oxygen (O), carbon (C), hydrogen (H), and nitrogen (N).

Silicon is one of the most useful elements to mankind. Most is used to make alloys including aluminium-silicon and ferro-silicon (iron-silicon).

Liquids. A pure liquid has a constant/fixed boiling point. The more impurities a substance contains, the higher its boiling point will be. The substance would boil over a range of temperatures.

Pure, crystalline solids have a characteristic melting point, the temperature at which the solid melts to become a liquid. The transition between the solid and the liquid is so sharp for small samples of a pure substance that melting points can be measured to 0.1oC.

The water melting point depends on the pressure above the ice (solid water) and with increasing pressure, the melting point or freezing temperature decreases. By reference, 0 °C is the atmospheric pressure of 1 at the freezing point of water.