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please help me in this both Q 1) & 2) 1) What is the coordination number of... a

ID: 1041426 • Letter: P

Question

please help me in this both Q 1) & 2)

1) What is the coordination number of...

a) Na in Na(bcc)? b) Na in NaCl? c) Cl in CsCl?

2) In tribute to the late great Canadian penny: Canadian pennies before 1997 were a type of bronze alloy with 95-98 % Cu. Use the internet to assist in parts (a) and (b) below.

a) What two other elements were in the pre-1997 penny?

b) What became the dominant element in the 1997 penny alloy?

c) Do you think the 1996 Canadian penny was a substitutional, interstitial, or intermetallic-compound alloy?

Explanation / Answer

Coordination number is the number of atoms or ions immediately surrounding a central atom in a complex or crystal.

(1) (a) Na in body-centered cubic (bcc) has a coordination number of 8 with two atoms per unit cell.

(b) Na has the coordination number of 6 in NaCl.

(c) Cs has the coordination number of 8 in CsCl.

(2) (a) Tin and Zinc were the other two elements used for Canadian penny in its pre-1997 version.

(b) But in 1997 Zinc replace copper as the dominant element (about 98.4%), remaining was copper plating.

(c) 1996 Canadian penny was a substitutional alloy where some of the copper atoms are replaced by atoms of Tin and Zinc in the crystal lattice.