Which of the following pairs of elements would be Least likely to form a compound by ionic bonding?

1. Na and S

2. Al and F

3. Mg and Br

4. Cs and O

5. C and N

Na and S is ionic it has 1.6 electronegativity

Al and F is not ionic since they are both nonmetals

Mg and Br is ionic has 1.6 electronegativity

Cs and O is ionic and it has 2.8 electronegativity

C and N isnt ionic because both are nonmetal.

when it means least what is it looking for i’d assumer its Na and S or Mg and Br but since they’re both 1.6 i dont know what to do.

It might be possible some of the answers i written off as non-ionic could be ionic since 2.0+ is ionic in electronegativity.

2 Answers

  • When you continue studies in Chem you find ionic/covalent form a scale where few compounds are completely covalent (homonuclear) or 100% ionic, so most covalent is C and N as you predict they are closest in electronegativity

    Cs2O is most completely ionic with all the rest on the continuum. AlF3 is most definitely covalent in character but the bonds are polar.

    http://en.wikipedia.org/wiki/Aluminium_fluoride

  • 5. C and N… these are very likely to form a covalent bond, but not an ionic bond. (continue looking at electronegativities.)

    PS Al Aluminum is a metal

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