1. Period three
TRENDS

2. 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

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

4. reactivity- ability of an element to undergo chemical changesNa
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

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

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

7. 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 --