What Are Allotropes? Non-Metals

In this video we will looks at what allotropes are, and different examples of them. The term allotrope refers to different forms of the same element. Diamond and graphite are made of only carbon atoms – yet they exhibit very different physical and chemical properties. These differences are due to the arrangement of carbon atoms within the structure. Each carbon atom in diamond is covalently bound to four other carbon atoms in a tetrahedral structure. Each carbon atom in graphite is covalently bound to three other carbon atoms, forming hexagonal sheets. Other allotropes of carbon include buckminsterfullerene and graphene. Allotropism also exists in other elements, such as oxygen, phosphorus, and sulfur. Oxygen can exist as diatomic oxygen, O2, which is the form that we breathe in and is vital for survival. In this allotrope, two oxygen atoms are held together by a double covalent bond. Oxygen can also exist as ozone, O3, which forms the ozone layer in the Earth’s atmosphere. Red phosphorus is an allotrope of phosphorus. Matches made of red phosphorus are known as safety matches – in order to ignite, it must be struck against the striking surface on the outside of the package.Before the introduction of red phosphorus, the match heads were usually made of white phosphorus – another allotrope of the element.The different colours arise from their different structures! White phosphorus consists of four phosphorus atoms, held together in a tetrahedral arrangement.Other allotropes of phosphorus also exist – black phosphorus and violet phosphorus. Sulfur exists as many allotropes – the one that you’re most likely familiar with is S8, octasulfur, a bright yellow solid. Another solid allotrope of sulfur is hexasulfur, S6. Sulfur can also exist as gaseous allotropes – disulfur, S2, and trisulfur, S3. Allotropism also exists in some metalloid elements and metals.