THE IRON FAMILY
| SYMBOL | ATOMIC WEIGHT | DENSITY | APPROXIMATE MELTING POINT | OXIDES | |
| Iron | Fe | 55.9 | 7.93 | 1800° | FeO, Fe2O3 |
| Cobalt | Co | 59.0 | 8.55 | 1800° | CoO, Co2O3 |
| Nickel | Ni | 58.7 | 8.9 | 1600° | NiO, Ni2O3 |
The family. The elements iron, cobalt, and nickel form a group in the eighth column of the periodic table. The atomic weights of the three are very close together, and there is not the same gradual gradation in the properties of the three elements that is noticed in the families in which the atomic weights differ considerably in magnitude. The elements are very similar in properties, the similarity being so great in the case of nickel and cobalt that it is difficult to separate them by chemical analysis.
The elements occur in nature chiefly as oxides and sulphides, though they have been found in very small quantities in the native state, usually in meteorites. Their sulphides, carbonates, and phosphates are insoluble in water, the other common salts being soluble. Their salts are usually highly colored, those of iron being yellow or light green as a rule, those of nickel darker green, while cobalt salts are usually rose colored. The metals are obtained by reducing the oxides with carbon.