Post assessment revision

SCIENCE POST ASSESSMENT REVISION

• Development of the Periodic Table
• Explaining trends of the Periodic Table

Development- arrangement

• The classic periodic table was organized by the number of protons that the nucleus had. It was arranged in the order of increasing proton number.
• Mendeleev organized the elements based on Atomic Weight, but was arranged periodically. He put elements that had similar properties together but one on top of the other. He also left gaps in the table in case new elements were discovered.

Periodic table trends

• Elements within groups have certain physical and chemical properties, this determines how they react, also other groups have different trends, in terms of reactivity, as you move down.
• The reactivity of the groups increase as you move down, this is because the electrons in the outer shell gets further away from the nucleus. This means that elements with more electrons and more shells, the more reactive it is.