Monthly Archives: November 2018

Language of bonding

The golden rule in writing about bonding is to be clear about what particles are attracted to each other and what that attraction is.

Do not use the words atoms, ions, and molecules carelessly. A wrongly chosen word can throw away all your marks.

If a question is asking about the high melting point of magnesium oxide, a student will not get much credit for just saying it has strong bonds or strong ionic bonds.

A good answer might be: MgO has a giant lattice structure with strong electrostatic forces of attraction between oppositely charged ions. These require a lot of energy to break.

Similarly if talking about hydrogen bonding in ethanol it is essential to make to make it clear that you know  it exists between  ethanol molecules.

Statements like ethanol has hydrogen bonding, or contains hydrogen bonds are too vague, and potentially hint at a misunderstanding. Some students mistakenly believe the hydrogen bond in ethanol is the actual O-H covalent bond within the molecule. Any confusion with covalent bonds will result in losing all the marks in the question.

A good way of phrasing it is that ethanol forms hydrogen bonds between  molecules.

 

 

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