AP Chemistry
Worksheet : Ch. 8 : Obj. 1 - 20
Name :
Date :
A. Read pp. 329 - 381 and answer the following questions :
1. ____________________________ are the forces that hold atoms together to make them function as a unit.
2. ____________________________ is the energy required to break a chemical bond.
3. _____ (T/F) Atoms or ions bond to achieve the lowest (most stable) energy state possible.
4. _____ (T/F) Ions in ionic bonds are held together by the mutual sharing of electrons.
5. Write the mathematical expression for Coulomb's law
6. _____ (T/F) Larger ions (larger r value) have a greater energy of interaction than smaller ions with the
same charge difference.
7. _____ (T/F) Ions with smaller charges have a greater energy of interaction than ions of the same size with
a larger charge difference.
8. _____ (T/F) The bond length of a bond is the distance where the sum of the repulsive energies (protonproton and electron-electron forces) and the attractive energies (proton-electron forces) are at a
minimum.
9. _____ (T/F) The zero point of energy is defined as the point where the atoms are at an infinite separation.
10. _____ (T/F) Atoms in covalent bonds are held together by the electrostatic attraction of their opposite
charges.
11. ______________________ covalent bonds result when electrons are shared unequally.
12. ___________________________ is the ability of an atom in a molecule to attract shared electrons to
itself.
13. How are the electronegativities of elements determined?
14. _____ (T/F) The greater the electronegativity difference between two bonded atoms, the greater the ionic
character of the bond.
15. _____ (T/F) Electronegativity increases down a group.
16. _____ (T/F) Electronegativity decreases across a period.
17. _____ (T/F) Molecules with a positive and negative centers are said to be dipolar (have a dipole moment).
18. _____ (T/F) Molecules may have polar bonds and be nonpolar.
19. List three molecular geometries which have polar bonds, but do not result in a dipole moment.
20. _____ (T/F) The CH4 and the CH3Cl molecules have tetrahedral geometry and therefore both are
nonpolar.
21. _____ (T/F) Ionic compounds are solids (gaseous and aqueous ionic substances are dissociated).
22. _____ (T/F) In the ionic compound CaCl2, both the calcium ions and the chloride ions have the electron
configuration of argon.
23. _____ (T/F) In the covalent compound NO2, the nitrogen and oxygen atoms share electrons in such a way
so that both elements have the electron configuration of neon.
24. _____ (T/F) Ion size increases as electrons are lost.
25. _____ (T/F) Metallic ions are larger then the nonmetallic ions of the same period.
26. _____ (T/F) The size of isoelectronic ions decreases as nuclear charge (Z) increases.
27. ________________________ energy is the change in energy that takes place when separated gaseous
ions are packed together to form an ionic solid.
28. Match the following for the formation of magnesium chloride :
_____ second ionization of magnesium
_____ enthalpy of dissociation of chlorine
_____ sublimation of magnesium
_____ first ionization of magnesium
_____ electron affinity of chlorine
_____ overall energy change
_____ lattice energy of magnesium chloride
29. Write the equation for the calculation of
lattice energy.
30. _____ (T/F) According to the equation for the calculation of percent ionic character there is no such thing
as a pure ionic bond.
31. ________________________ compounds are substances that conduct an electric current when dissolved
or melted.
32. _____ (T/F) The strength of a particular bond is independent of the molecular environment it is in (other
bonds within that molecule).
33. _____ (T/F) Triple bonds are longer than double bonds which are longer than single bonds.
34. _____ (T/F) In general, double and triple bonds have higher energies than single bonds.
35. _____ (T/F) Bond breaking is an exothermic process (ΔH is negative).
36. _____ (T/F) Bond forming is an endothermic process (ΔH is positive).
37. Write the equation for the calculation for the enthalpy change of a chemical reaction.