Light metal: Metals with a density below 4.5 g·cm-3 are […]
Light metal: Metals with a density below 4.5 g·cm-3 are called light metals. For example, sodium, potassium, magnesium, calcium, aluminum, and the like. Groups IA and IIA in the periodic system are all light metals. Heavy metals: Generally, metals with a density above 4.5 g·cm -3 are called heavy metals.
For example, copper, zinc, diamond, nickel, tungsten, molybdenum, niobium, tantalum, lead, tin, cadmium, mercury, etc., transition elements are mostly heavy metals. Precious metals: Precious metals usually refer to gold, silver and platinum group elements.
These metals are less abundant in the earth's crust, are less prone to mining, and are more expensive, so they are called precious metals. These metals are more stable to oxygen and other reagents, and gold and silver are often used to make ornaments and coins. Rare metals: Rare metals usually refer to metals that are less or less distributed in nature. They are difficult to extract from raw materials and are industrially prepared and applied later. There are no strict limits between rare metals and ordinary metals. For example, some rare metals have more content in the earth's crust than metals such as copper, mercury and cadmium.