Download Dmitri MendeleevанааA Russian chemist, noticed a repeating

Dmitri Mendeleev ­ A Russian chemist, noticed a repeating pattern of chemical properties in the elements that were known at the time. Mendeleev arranged the elements in the order of increasing atomic mass to form something close to the modern day periodic table. The pattern of repeating order is called periodicity. 1
1. Nuclear Charge ­ the number of protons will attract the outermost electrons. An increased nuclear charge will attract electrons more pulling the electrons in closer and decreasing the atomic radius. 2. The # of electron shells (Principle Energy Levels) affect the atomic radius. The higher the principle energy level of the valence electrons the bigger the radius 3. The Electron Cloud effect ­ as an atom gets larger and has more electron shells the farther those shells become spaced apart. This is because the inner shells block the outer shells from the pull of the nucleus's positive pull. 2