Why does a difference in electronegativity between atoms lead to ionic bonding?

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Mohammed Ashfaq
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The metal oxides (Na2O, MgO, Al2O3 ) are ionic. They have high melting points. They have Ionic giant lattice structures: strong forces of attraction between ions : higher mp. They are ionic because of the large electronegativity difference between metal and O

Please can someone explain in simple terms why electronegativity difference make something ionic instead of covalent or even metallic? and why ionic bonding leads to higher melting points in comparison to covalent bonding or metallic bonding?

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charco
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(Original post by Mohammed Ashfaq)
The metal oxides (Na2O, MgO, Al2O3 ) are ionic. They have high melting points. They have Ionic giant lattice structures: strong forces of attraction between ions : higher mp. They are ionic because of the large electronegativity difference between metal and O

Please can someone explain in simple terms why electronegativity difference make something ionic instead of covalent or even metallic? and why ionic bonding leads to higher melting points in comparison to covalent bonding or metallic bonding?

Thanks
Metals lose electrons relatively easily. Electronegative elements capture electrons relatively easily. It's a symbiotic (type) relationship leadin to transfer of electrons.

Your last statement is not 100% correct.

Giant covalent bonding is probably stronger/on a par with/ than the strongest giant ionic bonding. These are similar to the strongest metallic bonding. Recognise the pattern?

Giant covalent
Carbon (diamond) m.p. 3800K (sublimes)

Giant ionic
Magnesium oxide: 3098K

Metallic
Tungsten: 3695K

The current highest melting point goes to tantalum hafnium carbide,
Ta4HfC5 at 4215K, although apparently there is a competitor in the pipeline.

Generalisations are dangerous, but you are safe(ish) to say that simple covalant substances usually have the lowest melting points.
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anosmianAcrimony
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Bonds are sharings of electrons, and electronegativities describe the extent to which atoms attract electrons to their side of those bonds. Halogens and oxygen are very, very good at attracting electrons to their side of the bonds they make, and the alkali metals and alkali earth metals like sodium and magnesium are really bad at attracting electrons to their side of a bond. So when a halogen atom and an alkali metal atom bond, instead of sharing the electron pair, the halogen just takes it and becomes a cation and the alkali metal becomes an anion.

Smaller differences in electronegativity give rise to polar bonds like those that form in water and in C-O bonds. These are somewhat negatively charged on one end and positively charged on the other.
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macpatgh-Sheldon
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Same reason, to make a biology analogy, as the attraction of a female of any species (symbol for female has a "plus" sign in it) towards males of the same species (kinda -ve).

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