The basics of metals

Metal generally refers to a class of substances with unique luster (that is, strong reflection of visible light) but not transparent, ductile and conductive. In the narrow sense, the concept of metal is a simple substance composed of metallic elements. Pure metals are generally solid at room temperature (except mercury), and most of them are good conductors of electricity and heat, with higher density and higher melting point. The metal resources of the earth exist widely in the Earth's crust and ocean, except for a few very inert metals such as gold, silver and so on exist in the form of elemental, the rest are in the form of compounds. Metals exist widely in nature, are widely used in life, and are very important and most used in modern industry.

Synthetic metal

A substance with metallic properties consisting of two or more chemical elements, at least one of which is a metallic element, is called an alloy. Alloys made up of two elements are collectively called "binary alloys", and alloys made up of more than three elements are generally called "multicomponent alloys". The structure and properties of alloys are determined by the interaction between the components of the alloy.

The crystals of alloys are composed of atoms of different kinds and have different crystal structures and properties depending on the interaction of the constituent elements. Nichcr alloy has high resistivity and heat resistance (1000℃ ~ 1200℃), commonly used as electric furnace wire. Aluminium alloys are close to high quality steel in strength per unit weight. Beryllium bronze has very high hardness and strength, good elasticity, strong corrosion resistance, good weldability and machinability, and is often used in the manufacture of special bearings, elastic components, spark-free tools. Because alloys' mechanical, physical and chemical properties are often superior to those of pure metals, almost all metal materials used in industry are alloys.

Classification of metals

Ferrous metal: iron, chromium, manganese three.

Non-ferrous metals: Aluminum, magnesium, potassium, sodium, calcium, strontium, barium, copper, lead, zinc, tin, cobalt, nickel, antimony, mercury, cadmium, bismuth, gold, silver, platinum, ruthenium, rhodium, palladium, osmium, Ridium, beryllium, lithium, rubidium, cesium, titanium, zirconium, hafnium, vanadium, niobium, tantalum, tungsten, molybdenum, gallium, indium, thallium, germanium, rhenium, lanthanum, cerium, prasmium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, scandium, yttrium, silicon, boron, Selenium, tellurium, arsenic, thorium [5].

Common metals: such as iron, aluminum, copper, zinc, etc.

Rare metals: such as zirconium, hafnium, niobium, tantalum, etc.

Light metal: metal elemental density less than 4500kg/m3, such as titanium, aluminum, magnesium, potassium, sodium, calcium, strontium, barium, etc.

Heavy metals: The density of metal elements is greater than 4500kg/m3, such as copper, nickel, cobalt, lead, zinc, tin, antimony, bismuth, cadmium, mercury, etc.

Precious metals: More expensive than common metals, low crustal abundance (also known as CLARKE value, a number indicating the average amount of chemical elements in the earth's crust) and difficult to purify, such as gold, silver and platinum group metals.

Quasi - metallic elements: having properties between metals and nonmetals, such as germanium, antimony, polonium, etc.

Rare metals: including rare light metals, such as lithium, rubidium, cesium, etc.; Rare refractory metals: such as zirconium, molybdenum, tungsten, etc. Rare dispersed metals: such as gallium, indium, germanium, thallium, etc. Rare earth metals: such as scandium, yttrium, lanthanide metals; Radioactive metals: such as radium, francium, polonium and actinide uranium, thorium, etc.

Metal tops

Most abundant metallic element in the Earth's crust: Aluminum (7.73%)

Most abundant metal in the body: Calcium (1.5%)

By far the world's largest annual production of metal: iron

Least dense metal: Hydrogen (In January 2016, British scientists made the first metallic form of hydrogen at the University of Edinburgh, hydrogen became the least dense metal)

The largest density of metal: osmium (22.48×10³㎏/m³)

Hardest metal: Chromium (Mohs hardness about 9)

Softest metal: Cesium (about 0.5 Mohs hardness)

The most conductive metal: Silver

The most thermally conductive metal: Silver

The most important metal for building new high-speed aircraft: titanium (dubbed by scientists as the "metal of the 21st Century" or the "steel of the future")

The most abundant radioactive element in seawater: uranium (about 2 million tons of uranium deposits on land, up to 400,000 tons in the ocean)

Most isotopic element: Tin (with 10 stable isotopes)

Element with least isotope: Sodium (only Na-23 is stable)

The most malleable metal: Gold (the thinnest gold thickness is only 1/10000mm)

Best ductile metal: platinum (the smallest platinum wire diameter is only 1/5000mm)

Metal with the highest melting point: Tungsten (melting point: 3410℃)

Metal with lowest melting point: Mercury (melting point: -38.8℃)

The element with the largest difference in melting boiling point is gallium (melting point 30℃, boiling point 2403℃).

The least abundant metal in the earth's crust is francium (only 37×10-13g per ton, even in the most abundant ore; The amount in the crust is about 1×10-21 %)

The metal element most likely to generate current under light: cesium (when its surface is hit by light, electrons gain energy to escape from the surface, producing photocurrent)

The most powerful metal for gold: cesium

World's most expensive metal: Californium ($10 million per gram, more than 500,000 times more expensive than gold)

Cheapest metal in the world: Iron

Most accessible superconducting element: Niobium (cooled to -263.9℃, it becomes a superconductor with virtually no resistance)

Most gas-absorbing metal element: Palladium (1 volume of colloidal palladium can absorb 1200 volume of hydrogen)