I need predict the bond type for NaCN. Also, for covalent molecules, specify also whether the molecule as a whole is polar?

The Na to CN bond is ionic. The C to N bond (it's C triple bond N) is covalent, specifically sp hybridization. Certainly the molecule is polar because of the ionic nature of the molecule.

To predict the bond type for NaCN (sodium cyanide), you need to determine the types of atoms involved in the bond and their electronegativities. Sodium (Na) is a metal, and Cyanide (CN) is a polyatomic ion.

Step 1: Determine the electronegativity difference:
- Find the electronegativity values of sodium and cyanide. Electronegativity is the ability of an atom to attract electrons towards itself.
- Sodium has an electronegativity value of around 0.9.
- Cyanide (CN) is composed of carbon (C) and nitrogen (N).
- Carbon has an electronegativity value of around 2.5.
- Nitrogen has an electronegativity value of around 3.0.
- Calculate the electronegativity difference by subtracting the electronegativity of sodium from the average electronegativity of carbon and nitrogen:
Electronegativity difference = Average electronegativity of CN - Electronegativity of Na

Step 2: Determine the bond type based on electronegativity difference:
- A difference in electronegativity greater than 1.7 indicates an ionic bond.
- A difference in electronegativity between 0.5 and 1.7 indicates a polar covalent bond.
- A difference in electronegativity less than 0.5 indicates a nonpolar covalent bond.

By following these steps, you can calculate the electronegativity difference and determine the bond type for NaCN.