Apentix/AP Chemistry/Unit 2: Molecular and Ionic Compound Structure and Properties/Question

AP Chemistrymediummcq1 pt

Compared with the H-Br bond, the H-Cl bond:

A.is stronger and shorter because smaller chlorine orbitals overlap hydrogen more effectively

B.is weaker because bromine is the heavier atom

C.is longer because chlorine holds more protons

D.has the same length and energy because both bonds are single

Explanation

Core Concept

Both bonds are single, so strength differences come from size and overlap rather than bond order. Chlorine sits above bromine on the periodic table, so its valence shell is smaller and its bond to hydrogen is shorter. Shorter distance means better orbital overlap and more energy needed to break the bond: measured enthalpies give about 431 kJ/mol for H-Cl versus about 366 kJ/mol for H-Br.

Correct Answer

Ais stronger and shorter because smaller chlorine orbitals overlap hydrogen more effectively

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