some substances such as sodium cloride so not contain discrete molecules as their constituent units.in such compounds ,+ve and -ve entities are arranged in a 3-dimensional structure-necrt chemestry.here why and how molecules of NaCl come and form a solid body?

as we know that +ve and -ve ions attracts each other to form molecule but why all the molecules join to form a big solid body?and what is formula mass?

Asked by Kamlesh Sahu | 5th May, 2014, 01:27: PM

Expert Answer:

1.  Depending upon the size and charge of a particular ion, number of oppositely charged ions gets attracted by it, but, in a definite number.
For an example, in sodium chloride crystal each Na+ is surrounded by 6 Cl- ions and each Cl- ion by six Na+ ions.

2.  Ionic compounds in the crystalline state consist of orderly arranged cations and anions held together by electrostatic forces of attraction in three dimensions.

3.  NaCl is said to possess face centered cubic lattice crystal structure.

4.  The number of oppositely charged ions that surround a given ion of a given charge is known as the coordination number of that given ion.

5.  In sodium chloride crystal, the coordination number of Na+ is 6 and that of Cl- is also 6.

Answered by Prachi Sawant | 6th May, 2014, 05:49: PM

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