Is a diamond a single molecule?
It's a crystalline lattice of LOTS of carbon atoms with lots of admixtures, too.
yes. pure diamond is a single molecule. It is a bunch of carbon molecules which have all covalently boded to eachother in a tetrahedral arangement. The covalent bonds are stronger then ionic bonds which is why you can split a chunk of salt really easily, but with a diamond, tough luck. An interesting thing to note is that diamond spontaneously turns back into graphite at STP. But it takes a while.
Just a little while
You can break a chunk of salt very much easier than a piece of diamond not because the ionic bonds are weaker than covanlent bonds. In diamond, molecules link togherther by covalent bonds. In NaCl , Na+ and Cl- are linked very tightly for ionic strong ionic bond. But linkages between one molecule NaCl and another molecule NaCl are not ionic, they are held by coulomb force which are weaker than Na+ and Cl-.
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