Download atomic structure and interatomic bonding

MSE 235-Materials Science for Electronics Engineers
ASSIGNMENT-1
ATOMIC STRUCTURE AND INTERATOMIC BONDING
1)Cite important concepts associated with the Bohr model and wave mechanical model of the atom.
2) (a) Give the electron configurations of Ti; Ti2+, Cu; Cu+, F-, Ca, Ca2+
(b) Calcium Floride (CaF 2 ) exhibits predominantly ionic bonding. The Ca2+ and F- ions have electron structures that are identical to which inert
gases?
Atomic numbers(Z); Ti=22, Cu=29, F=9, Ca=20)
E
4)The net potential energy between two adjacent ions, E N , may be represented by;
ro
E N = -(A/r) + B/rn (where A and B are constants)
a)
b)
Determine the equilibrium interionic spacing, r o
(Hint: derivative of net potential energy with respect to interatomic spacing is zero)
Determine the expression for E o
Eo
r
5) Schematically draw energy (E) versus interatomic separation (r) curves for aluminum and Al 2 O 3 on the same graph and discuss the differences
between these curves in terms of bonding energy (E o ), bond length (r o ) and melting points by labelling the critical points on the curve.
6) Briefly cite the main differences between ionic, covalent and metallic bonding
7) The percent ionic character of a bond between elements A and B (A being the most electronegative) may be approximated by the expression;
%ionic character = (1-e-(0.25)(XA-XB)2)x100
X A and X B are the electronegativities for the respective elements. Compute the percent ionic character of the interatomic bonds for the following
compouns: TiO
8) Determine the number of covalent bonds that are possible for atoms of the following elements: Cl, F.
9) (a) What type of bonding would be expected for each of the following materials and compounds:
Poly vinly chloride (PVC)
, Brass (Cu-Zn), CaO, NaCl, H 2 0, CO 2 , HCl
(b) What type of intermolecular bonding (bonding between molecules) would be expected for each of the compounds; HF-HF, HCl-HCl, H 2 O-H 2 O.