Nickel is a silver-white metal. It is easily polished (made shiny). It is magnetic. It is not magnetic when heated above 355 °C (671 °F). It is not soft like many other metals. It can be stretched into wires easily. It is not radioactive.
Nickel is found in two oxidation states: +2, nickel(II); and +3, nickel(III). Nickel(II) is more common. Nickel in its +2 oxidation state is green. Nickel(II) chloride is a common +2 oxidation state compound. Nickel(II) oxide is normally dark green, but sometimes it is gray. This is because some of the nickel is in the +3 oxidation state (nickel(III). Nickel(III) compounds are oxidizing agents. They also are grayish. Nickel compounds can be green, blue, gray, or black.
- Nickel(II) compounds
Nickel(II) compounds are not highly reactive. They are normally green or blue. They are toxic and irritate skin. Some of them are carcinogens.
- Nickel(II) carbonate, green
- Nickel(II) chloride, greenish
- Nickel(II) hydroxide, light green
- Nickel(II) nitrate, greenish
- Nickel(II) oxide, gray or light green
- Nickel(II) sulfate, blue-green
- Nickel(III) compounds
Nickel(III) compounds are black or gray.
Nickel is not normally found as a metal in the ground. Sometimes meteorites have nickel and iron metal in them. Normally nickel is in minerals. The most common nickel mineral is pentlandite. There are sulfidic and lateritic nickel ores. Philippines mines the most nickel. Other major mining countries are Russia, Canada and Australia.
Nickel was found when a copper-coloured ore did not make copper metal. Later it was found out that the ore was actually a nickel containing ore. Nickel was isolated as a metal in 1751. At first, the copper colored nickel ore was the only source. Later, it was made as a byproduct of cobalt blue making.
Nickel is found in both laterite and sulfide ores. They are heated to melt them and concentrate them. They are also separated by oils. Nickel is made from its sulfide by heating it in air. This oxidizes the sulfide to sulfur dioxide, leaving liquid nickel behind. This nickel is not yet pure and not ready for use.
Pure nickel with a nickel content greater than 99% is made in an electrolytic process. In this process, the nickel is dissolved in bath of sulfuric acid. When the pure nickel sticks to cathodes hanging into the bath, the impurities remain in the sulfuric acid or at the bottom of the bath. These impurities are very interesting, as they can contain precious metals.
Sixty-eight percent of all nickel produced is used to make stainless steel. Nickel is also used in nichrome, a name for a nickel-chromium alloy, and other alloys. Nickel is used in magnets. Nickel is used in special expensive alloys called superalloys.
Nickel sulphate is used in rechargeable batteries. A lithium ion battery contains up to 15% of nickel while the lithium content is less than 1%. A nickel cadmium battery also uses nickel. Nickel compounds are also used to electroplate nickel on items. Nickel and some of its compounds are also used as a catalyst.
Nickel can irritate skin. That is why jewelry that releases nickel ions is bad for some people. Some nickel salts are carcinogens. Nickel is not as toxic as other metals such as mercury but it is still toxic.