Question

1. Why are the atomic weights of the elements generally not integers? Cite two reasons.


2. Give electron configurations for the Fe3+ and S2− ions.

3. Offer an explanation as to why covalently bonded materials are generally less dense than ionically or metallically bonded ones.

4. Calculate the force of attraction between a Ca2+ and an O2− ion the centers of which are separated by a distance of 1.25 nm.

5. The net potential energy between two adjacent ions, , may be represented by the sum of Equations 2.8 and 2.9; that is,
Calculate the bonding energy E0 in terms of the parameters A, B, and n using the follow- ing procedure:
a. Differentiate EN with respect to r, and then set the resulting expression equal to zero, since the curve of EN versus r is a minimum at E0.
b. Solve for r in terms of A, B, and n, which yields r0 , the equilibrium interionic spacing.
c. Determine the expression for E0 by substitution of r0 into Equation 2.11.

6. Compute the percentage ionic character of the interatomic bond for each of the following compounds: MgO and CdS.

7. Using Table 2.2, determine the number of co- valent bonds that are possible for atoms of the following elements: silicon, nitrogen, and neon.

Answer 1

Answer:

1. the atomic weights is not an integer because it is the average of the weight of the isotopes of the element .