Metals are divided into ferrous metals and non-ferrous metals. Black metal includes iron, Chromium, manganese; Non-ferrous metals refer to all metals other than iron, Chromium, and manganese. Non-ferrous metals can be roughly divided into the following five categories according to their density, price, reserves and distribution in the earth's crust, and sooner or later discovered and used by people.
(1) Non-ferrous metals: Non-ferrous metals with a density of less than 4.5. Including aluminum, magnesium, potassium, sodium, calcium, strontium, Barium.
(2) Heavy non-ferrous metals: non-ferrous metals with a density greater than 4.5. Including copper, lead, zinc, nickel, cobalt, tin, antimony, Mercury, cadmium, antimony and so on.
(3) Precious metals: refer to non-ferrous metals that are low in the earth's crust, difficult to extract and extract, stable to oxygen and other reagents, and more expensive than ordinary metals. Including gold, silver, platinum, Palladium, osmium, antimony, ruthenium, Rhodium.
(4) Semi-metal: Generally refers to five elements of Silicon, selenium, tellurium, arsenic, and boron. Its physical and chemical properties are between metals and non-metals. Arsenic, for example, is non-metallic, but it can transfer heat and conduct electricity.
(5) Rare metals: Rare metals are not said to be rare. They only mean that they are not widely distributed in the earth's crust, and mining and smelting are difficult. They are later used in industry and are therefore called rare metals. Including lithium, cesium, cesium, titanium, zirconium, niobium, niobium, tantalum, tungsten, Molybdenum, niobium, indium, niobium, niobium and so on.