Summarise how the elements are organised on the periodic table. In your answer, you should:State the order in which elements are placed in the table.Define period and group.Describe how the properties of the elements, and therefore their classification as a metal, non-metal or metalloid, changes as you move from left to right across the table.

The elements on the periodic table are organised based on their atomic number, which is the number of protons in an atom's nucleus. They are placed in order of increasing atomic number from left to right and top to bottom.

A period in the periodic table refers to a horizontal row. There are seven periods in the periodic table, and the period number of an element signifies the highest energy level an electron in that element occupies (in the unexcited state).

A group, on the other hand, refers to a vertical column in the periodic table. Elements in the same group share similar chemical properties because they have the same number of valence electrons, which are the electrons in the outermost shell of an atom that are involved in chemical reactions.

As you move from left to right across the table, the properties of the elements change. On the left side of the table, you find metals, which are typically shiny, good conductors of heat and electricity, and malleable. As you move towards the right, you encounter metalloids, which have properties of both metals and non-metals. Further to the right, you find non-metals, which are typically poor conductors of heat and electricity and not malleable or ductile. This change in properties is due to the increasing number of valence electrons as you move from left to right across a period.