Question

1. which of the listed molecules is not geometrically linear?

a. carbon dioxide (co₂) c. chlorine (cl₂)
b. water (h₂o) d. iron (fe₂)

1. when you use an arrow to indicate polarity what does the arrow head stand for?
2. if you have two different atoms around a central atom, such as the case in hcn which linear and asymmetrical unlike co₂ which has the same atoms around a central atom and is symmetrical, is the hcn molecule polar or nonpolar? think in terms of partial negativity.

a. polar due to its uneven distribution of electrons
b. nonpolar due to its linear asymmetry

1. thinking in terms of the negativity scale, a molecule that falls in the range of 1.8 to 4.0 should be considered what type of polarity?

a. covalent polar
b. covalent nonpolar
c. ionic

Explanation:

13.

• For \(CO_2\), the central \(C\) atom has \(sp\) hybridization and is linear (\(O = C=O\)).
• For \(Cl_2\), it is a di - atomic molecule and linear (\(Cl - Cl\)).
• For \(Fe_2\) (assuming it's a di - atomic metal molecule in a gaseous state for simplicity), it is linear.
• For \(H_2O\), the central \(O\) atom has \(sp^3\) hybridization with two lone pairs. The molecular geometry is bent (not linear) based on VSEPR theory (\(H - O - H\) with a bond angle of about \(104.5^{\circ}\)).

1. When using an arrow to indicate polarity, the arrow head points towards the more electronegative atom (or the region of higher electron density), representing the negative end of the dipole.
2. In \(HCN\), \(C\) is the central atom. \(N\) is more electronegative than \(C\), and \(C\) is more electronegative than \(H\). The electron distribution is uneven. The dipole moments do not cancel out (unlike \(CO_2\) where the two \(C - O\) dipole moments cancel each other due to symmetry). So, \(HCN\) is polar due to its uneven distribution of electrons.

16.

• For covalent non - polar bonds, the electronegativity difference (\(\Delta EN\)) is \(0\) (e.g., \(Cl_2\), \(\Delta EN=0\)).
• For covalent polar bonds, \(0\lt\Delta EN\lt1.7\).
• For ionic bonds, \(\Delta EN\geq1.7\). A value in the range of \(1.8 - 4.0\) for \(\Delta EN\) (considering the electronegativity scale) indicates an ionic bond.

Answer:

1. b. Water (\(H_2O\))
2. The negative end of the dipole (points to the more electronegative atom/region of higher electron density)
3. a. Polar due to its uneven distribution of electrons
4. c. Ionic