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The ions of NaF and MgO have the same nu...

The ions of NaF and MgO have the same number of electrons and internuclear distances are also about the same ( 235 pm and 215 pm ). Then why the melting points of NaF and MgO are different (`992^circ` C. and `2642^circ` C resp.)

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In .Mg^2+ O^2-.. both the ions carry two units of charge where as in .N a^+ F^-. each ion carries only one unit charge. Hence electrostatic force of attraction is stronger in MgO. Hence the melting point of .MgO. is much higher than that of .NaF..
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