if in a fcc unit cell A atoms are at corners B  atoms are at face centres and one of A atoms are missing from each unit cell then what is the formulae of compound

Asked by Farooq Ahmad Shah | 1st Nov, 2015, 08:53: PM

Expert Answer:

Number space of space atoms space of space straight A space at space the space corners space equals space 7 space left parenthesis because space one space is space missing right parenthesis Hence comma space contribution space of space straight A space topwards space unit space cell space equals space 7 space cross times 1 over 8 space equals space 7 over 8 Number space of space atoms space straight B space at space the space face minus centres space equals space 6 Hence comma space contribution space of space atom space straight B space towards space unit space cell space equals space 6 cross times 1 half equals 3 Ratio space of space straight A colon straight B space equals space 7 over 8 colon 3 equals 7 colon 24 Thus comma space the space formula space of space FCC space is space straight A subscript 7 straight B subscript 24

Answered by Prachi Sawant | 2nd Nov, 2015, 10:05: AM