What accounts for the difference in melting points of the substance?
Answer:
Because the forces are strong, ionic crystals have large lattice energies. They are not easily deformed , and they have high melting points.
In molecular crystals, molecules (sometimes individual atoms) occupy lattice sites. The attractive forces between the molecules are due to either dispersion forces or hydrogen bonds. These forces are much weaker than the covalent bonds that exist within the molecules. Because of this, molecular crystals tend to have small lattice energies and are easily deformed . Also, since relatively small amounts of thermal energy are required to overcome these forces of attraction due to temporary dipoles that form instantaneously and in a random fashion, molecular solids have low melting points...
Substances have different melting points because of different intermolecular forces in the solid.
Ionic bonds -- strongest (sodium chloride).
Hydrogen bonds -- very strong (sugar)
Dipole-dipole forces -- moderately strong (acetone)
Van der Waals forces -- weak (helium)
the atomic make up of a substence and atmosphere and pressure. different things have different melting points by its make up alone. but if you for example put water under pressure and vaccum like enviroment such as a car radiator system then the boiling point greatly increases
The physical make-up of the atoms of different elements requires different amounts of heat (energy) to cause the molecules of a substance to vibrate free of their bondings. When they can move freely, the substance is said to have melted.
The first answer is the correct answer. Thumbs up for you!
It is the energy, heat, (that can be variable through pressure - this is the second answerers point) that gives us a different volume, liquid, by breaking molecular bonds.
The energy required to break these molecular bond varies (see first answerer ^_^ )
The answers post by the user, for information only, FunQA.com does not guarantee the right.
More Questions and Answers: