Which of the following has the bonds correctly arranged in order of increasing polarity? a) Be - F, Mg - F, N - F, O - F b) O - F, N - F, Be - F, Mg - F c) O - F, Be - F, Mg - F, N - F d) N - F, Be - F, Mg - F, O - F e) Mg-F, Be - F, N - F, O - F

Question

Nikolai Stephenson

Chemistry

2 October, 19:55

Which of the following has the bonds correctly arranged in order of increasing polarity? a) Be - F, Mg - F, N - F, O - F b) O - F, N - F, Be - F, Mg - F c) O - F, Be - F, Mg - F, N - F d) N - F, Be - F, Mg - F, O - F e) Mg-F, Be - F, N - F, O - F

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Answers (2)

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Dayton Yang · Answer 1

Answer:b) O - F < N - F < Be - F < Mg - FExplanation:To calculate polarity, you need a table of electronegativities, to find the difference of electronegativities between each pair of atoms. The higher the electronegativity difference between the bonded atoms the higher the polarity of the bond. Nevertheless, you can calculate the relative order for the given pairs by using periodic table trends, following this reasoning:1) Be, N, O, and F are in the same period (row), in that same order from left to right. 2) In a period the electronegativity increases from left to right, so Be is the least electronegative, followed by N, followed by O, and F is the most electronegative. So, you can predict this order for the polarities: O - F < N - F < Be - F 3) Now you have to deal with Mg - F. You must use the fact that the electronegativity decreases in the periodic table in a group (column) from top to bottom. So, since Mg is directly below Be, you conclude that Mg is less electronegative and Mg - F is more polar than Be - F, and now you complete the order:O - F < N - F < Be - F < Mg - F, which is the option b). You can verify the conclusion using a table of electronegativities as follow:1) Start by writing the electronegativities of the elements stated in the question:Be: 1.57F: 3.98Mg: 1.31N: 3.04O: 3.44 2) Find the electronegative differences between each pair:Be - F: | 1.57 - 3.98 | = 2.41Mg - F: | 1.31 - 3.98 | = 2.67N - F: | 3.04 - 3.98 | = 0.94O - F: | 3.44 - 3.98 | = 0.543) Compare and order: 0.54 < 0.94 < 2.41 < 2.67 ⇒ O-F < N - F < Be - F < Mg - F, which is the same conclusion from above, option b. : 3

Alissa Murphy · Answer 2

option b) O - F < N - F < Be - F < Mg - F

Explanation:

To calculate polarity, you need a table of electronegativities, to find the difference of electronegativities between each pair of atoms. The higher the electronegativity difference between the bonded atoms the higher the polarity of the bond.

Nevertheless, you can calculate the relative order for the given pairs by using periodic table trends, following this reasoning:

1) Be, N, O, and F are in the same period (row), in that same order from left to right.

2) In a period the electronegativity increases from left to right, so Be is the least electronegative, followed by N, followed by O, and F is the most electronegative.

So, you can predict this order for the polarities: O - F < N - F < Be - F

3) Now you have to deal with Mg - F.

You must use the fact that the electronegativity decreases in the periodic table in a group (column) from top to bottom. So, since Mg is directly below Be, you conclude that Mg is less electronegative and Mg - F is more polar than Be - F, and now you complete the order:

O - F < N - F < Be - F < Mg - F, which is the option b).

You can verify the conclusion using a table of electronegativities as follow:

1) Start by writing the electronegativities of the elements stated in the question:

Be: 1.57 F: 3.98 Mg: 1.31 N: 3.04 O: 3.44

2) Find the electronegative differences between each pair:

Be - F: | 1.57 - 3.98 | = 2.41 Mg - F: | 1.31 - 3.98 | = 2.67 N - F: | 3.04 - 3.98 | = 0.94 O - F: | 3.44 - 3.98 | = 0.54

3) Compare and order:

0.54 < 0.94 < 2.41 < 2.67 ⇒ O-F < N - F < Be - F < Mg - F, which is the same conclusion from above, option b).