| ELEMENTO QUÍMICO | NÚMERO ATÔMICO | MASSA ATÔMICA |
| H | 1 | 1,0 |
| He | 2 | 4,0 |
| C | 6 | 12,0 |
| N | 7 | 14,0 |
| O | 8 | 16,0 |
| F | 9 | 19,0 |
| Ne | 10 | 20,0 |
| Na | 11 | 23,0 |
| Mg | 12 | 24,3 |
| S | 16 | 32,0 |
| Cℓ | 17 | 35,5 |
| K | 19 | 39,0 |
| Cr | 24 | 52,0 |
| Fe | 26 | 56,0 |
| Br | 35 | 80,0 |
| I | 53 | 127,0 |
| La | 57 | 139,0 |
| Pb | 82 | 207,0 |
| At | 85 | 210,0 |
No que se refere a sistemas em equilíbrio químico, assinale a afirmação verdadeira.
