The radii of Na+ and Cl- ions are 95 pm and 181 pm respectively. The edge length of NaCl unit cell is

Question

The radii of Na+ and Cl- ions are 95 pm and 181 pm respectively. The edge length of NaCl unit cell is (A) 276 pm (B) 138 pm (C) 552 pm (D) 415 pm

Tardigrade Admin · Accepted Answer

NaCl has fcc structure. In fcc lattice r++r-=(a/2) where a= edge length r+ =95 pm r-=181 pm Edge length =2 r++2 r-=(2 × 95+2 × 181) pm =190+362=552 pm

Q. The radii of $N a^{+}$ and $C l^{-}$ ions are $95 p m$ and $181 p m$ respectively. The edge length of $N a Cl$ unit cell is

$276 p m$

$138 p m$

$552 p m$

$415 p m$

NaCl has fcc structure.

In fcc lattice $r^{+} + r^{-} = \frac{a}{2}$

where $a =$ edge length

$r^{+} = 95 p m r^{-} = 181 p m$

Edge length $= 2 r^{+} + 2 r^{-} = (2 \times 95 + 2 \times 181) p m$

$= 190 + 362 = 552 p m$

Q. The radii of Na+ and Cl− ions are 95pm and 181pm respectively. The edge length of NaCl unit cell is

276pm

138pm

552pm

415pm