Compounds Facts
Compounds Facts
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| Interesting Compounds Facts: |
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| There are defined proportions for the elements that make up a chemical compound, and they are in direct ratios. |
| There are also defined properties, both physical and chemical, that make up compounds, and those properties are not the same as the properties of the elements involved. |
| Crystalline compounds on Earth, also called non-stoichiometric compounds, do not necessarily behave in this fixed ratio or fixed property way. |
| Also, compounds that are made up of isotopes of an element may have different mass ratios than compounds made up of the natural element. |
| There are four major types of compounds: molecular, salts, complexes, and intermetallic compounds. |
| Molecular compounds are made when the atoms of the constituent elements are held together with covalent bonds. |
| Salts are compounds whose atoms are held together with ionic bonds. |
| Complexes are joined by coordinate covalent bonds. |
| Intermetallic compounds are those whose element atoms are held together with metallic bonds. |
| Compounds are often defined by the term valency, which is the number of atoms of hydrogen that it takes to combine with atoms of an element in order to form a specific compound. |
| Compounds are often confused with mixtures, with the chief difference being that elements that make up the constituent parts of the compound do not retail their chemical properties, while the elements that make up a mixture do. |
| Mixtures like alloys and intermetallic compounds resemble pure compounds almost closely enough that the confusion in their case is understandable. |
| Compounds are written as chemical formulas. |
| Most formulas for compounds are expressed as either the molecular unit or as empirical formulas, as in the case of polymeric compounds. |
| There is a very specific order to listing the elements present in a compound, using the Hill system. |
| Under the Hill system, any carbon present is generally listed first, any hydrogen is listed next, and then any other elements present in the compound are listed alphabetically by their periodic symbol. |
| If there is no carbon in the formula, then all of the elements including hydrogen are listed alphabetically. |
| In ionic compounds, the positive ion is typically mentioned first, followed by the negative ion. |
| Of course, in the case of oxides, the oxygen present is mentioned last. |
| All compounds can exist as solids at sufficiently low temperatures, and many others can exist in different states, including plasma. |
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