2006-11-24 04:43:58 · 6 answers · asked by Dan L 1 in Science & Mathematics ➔ Chemistry
In order to move the ions further apart and so as to become a gas, a lot of energy is required as ionic bondings are strong.
In the case of covalent bonding, generally, small molecules (e.g. oxygen, water, carbon dioxide) are formed. Although the covalent bonds are also very strong, we do not have to break them to change the state of the substance. We merely have to separate the molecules which are held together by weak Van der Waals forces. (Please note that some covalent substances have got high melting and boiling points too as they exist as giant macromolecular structures, e.g. sand and diamond).
2006-11-26 02:56:40 · answer #1 · answered by Kemmy 6 · 0⤊ 0⤋
In ionic substances the particles (ions) are attracted to all those around them. This means that the structure is very large with a huge number of bonds. To melt the solid this large number of bonds need to be broken and this takes a high temperature. So to boil the solid takes an even higher temperature.
With molecular solids there are only very weak bonds holding the molecules together and the structure is not nearly as large.
A high melting and boiling point is common to most giant structures for example most metals.
2006-11-25 19:55:05 · answer #2 · answered by Examiner 3 · 1⤊ 0⤋
In covalent molecules the forces between the molecules tend to be very weak and easily broken. This means it is "easy" to get them to move apart into the liquid phase (low melting point) and the gas phase (low boiling point). They all tend to be either liquids or gases at room temperature.
Ionic compounds contain the same forces but IN ADDITION there are electromagnetic forces also holding it together. This is because there are + ions attracted to - ions (opposite charges attract, right?). This electromagnetic attraction is much stronger than the other forces and so it is harder to get these molecules to move apart into the liquid phase and gas phase. Most ionic compounds are solids are room temperature with fairly high melting and boiling points.
2006-11-24 15:05:05 · answer #3 · answered by The Old Professor 5 · 0⤊ 0⤋
Ionic bonds are the strongest chemical bonds and require a large energy to break.
2006-11-24 13:01:06 · answer #4 · answered by ag_iitkgp 7 · 0⤊ 0⤋
ionic substances are generally solids
covalent are more liquids used in chemistry
2006-11-24 12:46:18 · answer #5 · answered by Erik N 2 · 0⤊ 0⤋
because the links between the ions are very firm.
2006-11-24 12:55:13 · answer #6 · answered by zelenikaktus 4 · 0⤊ 0⤋