Q42 of 400 Page 169

Why has sodium chloride a high melting point?

the reason behind sodium having a high melting point is that, sodium chloride is an ionic compound and these compounds are made of up of positive and negative ions. There is a strong force of attraction between the oppositely charged ions, so, a lot of heat energy is required to break this force of attraction and melt or boil the ionic compound.

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42 |How many electrons are there in the outermost shell of (i) a sodium atom, and (ii) a chlorine atom? 42 Show the formation of NaCl from sodium and chlorine atoms by the transfer of electron(s). 42 Name the anode and the cathode used in the electrolytic refining of impure copper metal. 43 Write the electron arrangement in (i) a magnesium atom, and (ii) an oxygen atom.