The periodic table lists all the known elements

The periodic table lists all the known elements in order of increasing atomic number.

The periodic table Every box within the table represents a different atomic number and therefore a different element. Each element also has its own characteristic symbol, such as Cl for chlorine and Ag for silver. Hydrogen (element symbol H) contains atoms that have only one proton and so it has the atomic number 1. This makes hydrogen the first element of the periodic table. Oganesson (symbol Og) is the last, with 118 protons. So oganesson has the atomic number 118.

Periods and groups The periodic table lists the elements according to their atomic number but it also arranges them in rows and columns. This arrangement of periods and groups gives each element a specific spot in the table. Oxygen (O) is in period 2, group 16 Chlorine (CI) is in period 3, group 17 Potassium (K) is in period 4, group 1

Periods and groups The arrangement also places element with similar physical and chemical properties in the same group. Group 2 – beryllium, magnesium, calcium, strontium and barium. All react in much the same way and form similar compounds. Group 17 – fluorine, chlorine, bromine, and iodine. All act in a similar way in chemical reactions. Sodium and Potassium are in Group 1 – both of which burn brightly in air.

Special Blocks The periodic table also has three special blocks of element known as transition elements, lanthanides and actinides.