Period three TRENDS

Atomic Mass- mass of an atom 22.99amu Mg 24.31amu Al 26.98amu Si 28.09amu P 30.97amu S 32.06amu Cl 35.45amu Ar 39.95amu

Atomic size- radius of an atom 190pm Mg 145pm Al 118pm Si 111pm P 98pm S 88pm Cl 79pm Ar 71pm

reactivity- ability of an element to undergo chemical changes Na Reacts vigorously with water Mg Reacts only slightly with water Al Does not react with oxygen Si Reacts very slowly with oxygen P S Reacts slowly with metal Cl Reacts violently with metals Ar Unreactive

Shielding effect- full core shells blocking the positive nuclear force from reaching the valence shell Na 10 Mg Al Si P S Cl Ar

Ionization energy- energy required to remove an electron Na 490 Mg 730 Al 580 Si 780 P 1060 S 1000 Cl 1250 Ar 1520

Electronegativity- tendency of an atom to attract electrons 0.9 Mg 1.2 Al 1.5 Si 1.8 P 2.1 S 2.5 Cl 3.0 Ar --