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You might wonder why it chooses to use six orbitals rather than four or eight or whatever. It re-organises (hybridises) the 3s, the three 3p, and two of the 3d orbitals to produce six new orbitals all with the same energy. The aluminium uses six of these to accept lone pairs from six water molecules. That means that all the 3-level orbitals are now empty. Explore the atomic properties menu, following the links to atomic orbitals and electronic structures.Ĭome back to this page later using the BACK button, the History file, or the Go menu on your browser. Warning: It is a complete waste of time going any further with this page if you aren't confident about writing electronic structures in this form for elements and ions (including the first transition series). When it forms an Al 3+ ion it loses the 3-level electrons to leave Start by thinking about the structure of a naked aluminium ion before the water molecules bond to it. We are going to look in detail at the bonding in the complex ion formed when water molecules attach themselves to an aluminium ion to give Al(H 2O) 6 3+. It isn't, however, particularly important to the rest of this page that you know anything more than the fact that a substance which forms a co-ordinate bond by donating a lone pair of electrons to something else is known as a Lewis base. Note: If you haven't come across the term Lewis base, and want to find out more, you could follow this link to a page on theories of acids and bases. In other words, all ligands function as Lewis bases. These are used to form co-ordinate bonds with the metal ion.Īll ligands are lone pair donors. What all these have got in common is active lone pairs of electrons in the outer energy level. Simple ligands include water, ammonia and chloride ions. The molecules or ions surrounding the central metal ion are called ligands. If you follow this link, use the BACK button on your browser to return quickly to this page. Amongst other examples of co-ordinate bonding, that page contains a description of the bonding in the complex ion formed between aluminium ions and water molecules, and that will be repeated below on this page - so you needn't spend a lot of time reading that bit. Note: If you aren't sure about co-ordinate (dative covalent) bonding, you aren't going to make much sense of what follows without first following this link. (In some cases, the bonding is actually more complicated than that.) These can be considered to be attached to the central ion by co-ordinate (dative covalent) bonds. It discusses various sorts of ligand (including some quite complicated ones), and describes what is meant by co-ordination number.Ĭomplex metal ions containing simple ligandsĪ complex ion has a metal ion at its centre with a number of other molecules or ions surrounding it. This page explains the terms complex ion and ligand, and looks at the bonding between the ligands and the central metal ion. Therefore they can conduct as their ions are free to move.Introducing complex ions - ligands and bonding Ionic compounds dissolve in water easily, when they do this their lattice breaks up completely and water molecules surround the seperated ions. A cube of tightly packed alternate metal and non-metal ions. This is a regular repeating arrangement of metal and non-metal ions which creates compounds with very high melting points which conduct when molten or in solution but never when solid. Ionic compounds form what is known as a lattice structure. When these two charged particles come together they form an ionic bond because the positive magnesium ion is attracted to the negatively charged chloride ion. To become stable it must gain an electron to obtain a full outer energy level. Non-metals form negative ions because they gain electrons to become stable.Ĭhlorine (Cl) has an electron arrangement 2,8,7. They change into ions with a two positive charge. To become stable it must lose its two outer electrons to obtain a full outer energy level.Ītoms are neutral because they have equal numbers of protons and electrons however, when they lose two electrons they are no longer neutral. Magnesium (Mg) has the electron arrangement 2,8,2. Metals form positive ions because they lose electrons to become stable. The ionic bond is the electrostatic force of attraction between a positively charged metal ion and a negatively charged non-metal ion. Ionic bonds are formed between a metal and non-metal, for example sodium chloride.Īn atom of sodium will lose an electron and form a positive ion.Īn atom of chlorine will gain an electron and form a negative ion. Learn about the basic structure of an ion, related to atomic number and mass.
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