| # | Transition metal | ACTINIUM | (Gr.aktis,aktinos;ray or beam) | Ac | 89 | 227
|
|---|
| 1 | Group III element | ALUMINIUM | (L. alumen; alum) | Al | 13 | 26.98 |
| 2 | Actinide | AMERICIUM | (The Americas) | Am | 95 | 243 |
| 3 | Group V element | ANTIMONY | (L. antimonium,stibium;mark) | Sb | 51 | 121.76 |
| 4 | Noble gas | ARGON | (Gr. argon; inactive) | Ar | 18 | 39.94 |
| 5 | Group V element | ARSENIC | (L.arsenicum,Gr.arsenikon *) | As | 33 | 74.92 |
| 6 | Halogen | ASTATINE | (Gr. astatos; unstable) | At | 85 | 210 |
| 7 | Alkaline earth metal | BARIUM | (Gr. barys; heavy) | Ba | 56 | 137.36 |
| 8 | Actinide | BERKELIUM | (Berkeley,home of U.of Calif.) | Bk | 97 | 245 |
| 9 | Alkaline earth metal | BERYLLIUM | (L.beryl,also Gr.glykys *) | Be | 4 | 9.013
|
