Covalent structures and bonding
Read our general notes on Risk Assessment
Does anybody know the displayed formula for MgSO4 (magnesium sulphate)? I cannot seem to work it out!
Displayed formulae are generally used only for covalent, and particularly for organic, compounds. Magnesium sulphate, like nearly all simple compounds of metals, is an ionic compound.
The ions are Mg2+ and SO42–.
You could try to draw a displayed formula for a sulphate ion. I can't draw it here as we cannot (yet) do displayed formulae, but essentially there is a central sulphur atom joined to four oxygen atoms. Two of the oxygens are joined by double bonds and the other two by single bonds and each of these singly-bonded oxygens carries a negative charge.
If you try to draw a dot-and-cross diagram for the sulphate ion, remember that both sulphur and oxygen have 6 outer shell electrons, and as this is a 2– ion there are 2 extra electrons (given away by the Mg). As the sulphur atom is forming 6 bonds altogether, it has a total of 12 electrons around it and so it isn't conforming to the 'octet' rule.
There are quite a number of compounds involving elements in period 3 in which this happens; another examples is PCl5. Our course doesn't deal with these, but many A-level textbooks refer to them.
Jenkin
Risk assessment
Before attempting any practical work based on the advice and suggestions on this website, you must do the following. Identify any hazards, assess the risks from these hazards, and then decide appropriate control measures to reduce the risks. You must have these approved by those in authority in your school or college laboratory. Do not rely on what is said on this website.
For further guidance see our tutorial on Risk Assessment.
back to Covalent structures and bonding
Rate this page or react
Share your views on this page, 0 ratings so far
updated: 02 July 2003
