Predict whether the following bonds are ionic, covalent, or polar covalent based on
the bonding atoms electronegativities:
N2
The Al-O bond in Al2O3
MgO
CuS
Take the difference of electronegativity between the two atoms.
N to N = 3.0-3. = zero. Covalent.
If delta EN (electronegativity) = 1.8 or 1.9 that is about 50% ionic/50% covalent.
Between zero and 1.8 is olar covalent. We usually call those above 1.8 ionic but those very close to 1.8 or 1.9 still are polar covalent(although more ionic than covalent).
To predict whether a bond is ionic, covalent, or polar covalent based on the bonding atoms' electronegativities, we can use the concept of electronegativity difference. Electronegativity is a measure of an atom's tendency to attract electrons towards itself when it forms a chemical bond.
If the electronegativity difference between bonding atoms is small (less than 0.5), the bond is generally considered nonpolar covalent. If the electronegativity difference is moderate (between 0.5 and 2.0), the bond is considered polar covalent. On the other hand, if the electronegativity difference is large (greater than 2.0), the bond is ionic.
Now let's apply this concept to predict the nature of the given bonds:
1. N2:
Nitrogen (N) has an electronegativity value of 3.04. Since both nitrogen atoms have the same electronegativity, the electronegativity difference is zero. Therefore, the N2 bond is nonpolar covalent.
2. The Al-O bond in Al2O3:
Aluminum (Al) has an electronegativity value of 1.61, while oxygen (O) has an electronegativity value of 3.44. The electronegativity difference between Al and O is 1.83, which is between 0.5 and 2.0. Therefore, the Al-O bond in Al2O3 is considered polar covalent.
3. MgO:
Magnesium (Mg) has an electronegativity value of 1.31, while oxygen (O) has an electronegativity value of 3.44. The electronegativity difference between Mg and O is 2.13, which is greater than 2.0. Therefore, the Mg-O bond in MgO is ionic.
4. CuS:
Copper (Cu) has an electronegativity value of 1.90, while sulfur (S) has an electronegativity value of 2.58. The electronegativity difference between Cu and S is 0.68, which is less than 0.5. Therefore, the Cu-S bond in CuS is nonpolar covalent.
By considering the electronegativity differences between the bonding atoms, we can predict the nature of the bonds as follows:
- N2: nonpolar covalent
- The Al-O bond in Al2O3: polar covalent
- MgO: ionic
- CuS: nonpolar covalent