Valency of Elements and Groups of Atoms

The table below lists the valencies of some commonly encountered elements and groups of atoms:

| Element/Group | Valency |

|—|—|

| H (Hydrogen) | 1 |

| He (Helium) | … |

| Li (Lithium) | 1 |

| Be (Beryllium) | 2 |

| B (Boron) | 3 |

| C (Carbon) | 2, 4 |

| N (Nitrogen) | 3, 2, 4, … |

| O (Oxygen) | 2 |

| F (Fluorine) | 1 |

| Ne (Neon) | … |

| Na (Sodium) | 1 |

| Mg (Magnesium) | 2 |

| Al (Aluminum) | 3 |

| Si (Silicon) | 4 |

| P (Phosphorus) | 3, 5 |

| S (Sulfur) | 2, 4, 6 |

| Cl (Chlorine) | 1… |

| Ar (Argon) | … |

| K (Potassium) | 1 |

| Ca (Calcium) | 2 |

| Cr (Chromium) | 2, 3, … |

| Mn (Manganese) | 2, 4, 7, … |

| Fe (Iron) | 2, 3 |

| Cu (Copper) | 1, 2 |

| Zn (Zinc) | 2 |

| Br (Bromine) | 1 |

| Ag (Silver) | 1 |

| Ba (Barium) | 2 |

| Hg (Mercury) | 1, 2 |

| Pb (Lead) | 2, 4 |

| OH (Hydroxide) | 2 |

| NO3 (Nitrate) | 1 |

| SO4 (Sulfate) | 2 |

| CO3 (Carbonate) | 2 |

| PO4 (Phosphate) | 3 |

Notes:

• “…” indicates elements or groups of atoms that have no fixed valency or whose valencies have not been determined.

• The valency of some elements can vary depending on the compound they form.