[[chemistry]]

**"a charged chemical species composed of two or more atoms covalently bonded or of a metal complex, that can be considered to be acting as a single unit"

H stable at a duet 2d
Be stable at a tetrad 4e
B stable at a sextet 6e

| **Name**                                       | **Formula**                                                                                                                                                                                                                                                                                                            |
| ---------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Polyatomic ions (carrying negative charge)** |                                                                                                                                                                                                                                                                                                                        |
| Hydroxide                                      | OH [Matter and Chemical Bonding]]<br><br>add or remove valence e according to charge<br><br>H stable at a duet 2d<br>Be stable at a tetrad 4e<br>B stable at a sextet 6e<br>all other elements in pe 1 and 2 require octets 8e (common ball)<br>per 3 and below can go above an octet (common ball)<br><br><br><br>– |
| Acetate                                        | CH3COO –                                                                                                                                                                                                                                                                                                               |
| Cyanide                                        | CN –                                                                                                                                                                                                                                                                                                                   |
| Chlorate                                       | ClO3 –                                                                                                                                                                                                                                                                                                                 |
| Chlorite                                       | ClO2 –                                                                                                                                                                                                                                                                                                                 |
| Nitrate                                        | NO3 –                                                                                                                                                                                                                                                                                                                  |
| Nitrite                                        | NO2 –                                                                                                                                                                                                                                                                                                                  |
| Hypochlorite                                   | OCl –                                                                                                                                                                                                                                                                                                                  |
| Hypobromite                                    | OBr –                                                                                                                                                                                                                                                                                                                  |
| Iodate                                         | IO3 –                                                                                                                                                                                                                                                                                                                  |
| Bisulphite                                     | HSO3 –                                                                                                                                                                                                                                                                                                                 |
| Bisulphate                                     | HSO4 –                                                                                                                                                                                                                                                                                                                 |
| Permanganate                                   | MnO4 –                                                                                                                                                                                                                                                                                                                 |
| Thiocyanate                                    | SCN –                                                                                                                                                                                                                                                                                                                  |
| Hydrogen carbonate                             | HCO 3–                                                                                                                                                                                                                                                                                                                 |
| Carbonate                                      | CO3 2-                                                                                                                                                                                                                                                                                                                 |
| Sulphate                                       | SO4 2-                                                                                                                                                                                                                                                                                                                 |
| Sulphite                                       | SO3 2-                                                                                                                                                                                                                                                                                                                 |
| Oxalate                                        | C2O4 2-                                                                                                                                                                                                                                                                                                                |
| Silicate                                       | SiO3 2-                                                                                                                                                                                                                                                                                                                |
| Manganate                                      | MnO4 2-                                                                                                                                                                                                                                                                                                                |
| Thiosulphate                                   | S2O3 2-                                                                                                                                                                                                                                                                                                                |
| Chromate                                       | CrO4 2-                                                                                                                                                                                                                                                                                                                |
| Dichromate                                     | Cr2O7 2-                                                                                                                                                                                                                                                                                                               |
| Phosphate                                      | PO4 3-                                                                                                                                                                                                                                                                                                                 |
| Phosphite                                      | PO3 3-                                                                                                                                                                                                                                                                                                                 |
| Aluminate                                      | AlO3 3-                                                                                                                                                                                                                                                                                                                |
| Arsenite                                       | AsO3 3-                                                                                                                                                                                                                                                                                                                |
| Arsenate                                       | AsO4 3-                                                                                                                                                                                                                                                                                                                |
| Borate                                         | BO3 3-                                                                                                                                                                                                                                                                                                                 |
| Pyrophosphate                                  | P2O7 4-                                                                                                                                                                                                                                                                                                                |
| **Polyatomic ions (carrying positive charge)** |                                                                                                                                                                                                                                                                                                                        |
| Ammonium                                       | NH 4+                                                                                                                                                                                                                                                                                                                  |

## List of monatomic ions

- The ions made of a single atom are called **simple ions or monatomic ions**.

| **Name**                                      | **Formula** |
| --------------------------------------------- | ----------- |
| **Monatomic ions (carrying positive charge)** |             |
| Hydrogen                                      | H+          |
| Potassium                                     | K+          |
| Sodium                                        | Na+         |
| Silver                                        | Ag+         |
| Cuprous                                       | Cu+         |
| Aurous                                        | Au+         |
| Barium                                        | Ba2+        |
| Calcium                                       | Ca2+        |
| Magnesium                                     | Mg2+        |
| Cupric                                        | Cu2+        |
| Ferrous                                       | Fe2+        |
| Stannous                                      | Sn2+        |
| Mercuric                                      | Hg2+        |
| Zinc                                          | Zn2+        |
| Plumbous                                      | Pb2+        |
| Aluminum                                      | Al3+        |
| Ferric                                        | Fe3+        |
| Auric                                         | Au3+        |
| Arseneous                                     | As3+        |
| Plumbic                                       | Pb4+        |
| Stannic                                       | Sn4+        |
| **Monatomic ions (carrying negative charge)** |             |
| Chloride                                      | Cl–         |
| Bromide                                       | Br –        |
| Iodide                                        | I–          |
| Oxide                                         | O2-         |
| Sulphide                                      | S2-         |
| Nitride                                       | N3-         |
| Phosphide                                     | P3-         |