Which of the following contain polar covalent bonds? a. ammonia, NH3 C. ozone, O3 b. chlorine, Cl2 d. carbon monoxide, CO 8. In each of the following diatomic molecules, which end of the molecule is negative relative to the other end? (Write the formula and use partial plus and minus signs to show which end will have which charge) a. hydrogen chloride b. carbon monoxide c. iodine monochloride 9. Which ion would the following elements be expected to form? What noble gas has an analogous electron configuration to each of the ions? a. oxygen, Z=8 c. cesium, Z= 55 b. calcium, Z=20 d. selenium, Z- 34 None
The Correct Answer and Explanation is :
Answers and Explanation
1. Which of the following contain polar covalent bonds?
a. Ammonia (NH₃) – Contains polar covalent bonds. The nitrogen-hydrogen (N-H) bonds are polar because nitrogen is more electronegative than hydrogen. This creates a partial negative charge on nitrogen and partial positive charges on hydrogen.
b. Chlorine (Cl₂) – Does not contain polar covalent bonds. The bond in Cl₂ is a nonpolar covalent bond because the two chlorine atoms have the same electronegativity.
c. Ozone (O₃) – Contains polar covalent bonds. The oxygen atoms have unequal sharing of electrons due to the bent molecular shape and differing bond dipoles.
d. Carbon monoxide (CO) – Contains polar covalent bonds. The carbon-oxygen bond is polar due to the electronegativity difference, with oxygen having a partial negative charge and carbon a partial positive charge.
2. In each of the following diatomic molecules, which end is negative relative to the other?
- a. Hydrogen chloride (HCl):
H–Cl
The chlorine atom is partially negative (δ⁻) due to its higher electronegativity, and hydrogen is partially positive (δ⁺). - b. Carbon monoxide (CO):
C≡O
Oxygen is partially negative (δ⁻), and carbon is partially positive (δ⁺) due to the electronegativity difference. - c. Iodine monochloride (ICl):
I–Cl
Chlorine is partially negative (δ⁻) because it is more electronegative than iodine, which is partially positive (δ⁺).
3. Which ion would the following elements form, and what noble gas has an analogous electron configuration?
- a. Oxygen (Z = 8):
Forms O²⁻ by gaining 2 electrons to achieve the configuration of neon (Ne). - b. Calcium (Z = 20):
Forms Ca²⁺ by losing 2 electrons to achieve the configuration of argon (Ar). - c. Cesium (Z = 55):
Forms Cs⁺ by losing 1 electron to achieve the configuration of xenon (Xe). - d. Selenium (Z = 34):
Forms Se²⁻ by gaining 2 electrons to achieve the configuration of krypton (Kr).
Explanation
Polar covalent bonds occur when two atoms share electrons unequally due to differences in electronegativity. Nonpolar bonds, on the other hand, involve equal sharing of electrons between atoms with identical or very similar electronegativities. Molecules like NH₃, O₃, and CO exhibit polarity because of uneven electron distribution.
For diatomic molecules like HCl and CO, the atom with higher electronegativity attracts electrons more strongly, creating a dipole moment where one side is negative and the other is positive. In molecules like Cl₂, where atoms are identical, there is no dipole moment.
Ions form when atoms gain or lose electrons to achieve the stable electron configuration of a noble gas. Metals like calcium and cesium lose electrons to form cations, while nonmetals like oxygen and selenium gain electrons to form anions. This reflects the trend of elements seeking a stable, full outer shell configuration similar to the nearest noble gas.