DAT Bootcamp gen chem question

[Intent]

Which of the following best describes the bond character for aluminum sulfide (Al2S3)?
A. Polar covalent
B. Covalent
C. Ionic
D. Hydrophobic
E. Hydrogen bonding
Incorrect
The correct answer is A. Aluminum and sulfur are not very different in electronegativity (1.5 and 2.5, respectively) so the bond cannot be characterized as purely ionic. Their electronegativity is also not close enough to be considered a purely covalent bond. Only pure elements (N2, for example) are purely covalent. Thus, polar covalent is the correct answer.

Topic: Atomic and Molecular Structure

Hi, how come this can't qualify as ionic? I am asking because it is a metal bonded to a non-metal and I went with ionic. What do you guys think?

---

Members don't see this ad.

 

[bpester]

An ionic bond is characteristic of strong electronegativity differences between two elements, generally when you have an element on the far left side of the periodic table paired with an element on the far right side. Elements close to each other on the periodic table (similar electronegativities) will share electrons, forming a covalent bond. Unless the two elements are identical, the bond will be polar due to slight electronegativity differences. Aluminum is also a metalloid.

 

[Intent]

Thanks, I prefer your explanation

 

[namvis]

Also from what I know... ionic bond is usually between metal + non metal.

correct me if I am wrong.
thanks