Electronegativity And Polarity

Question 1

What do the nuclei of bonded atoms do in a covalent bond?

Answer 1

They attract the shared pair of electrons.

Question 2

What happens in molecules of elements?

Answer 2

The bonded electron pair is shared evenly.

Question 3

Why may polarity change when molecules contain different elements?
3 reasons

Answer 3

The nuclear charges are different.
The atoms may be different sizes.
The shared pair of electrons may be closer to one nucleus than the other.

Question 4

What do the shared pair of electrons from different elements in a molecule experience?

Answer 4

More attraction from one of the bonded atoms than the other.

Question 5

What is electronegativity?

Answer 5

The attraction of a bonded atom for the pair of electrons in a covalent bond.

Question 6

How is electronegativity measured?

Answer 6

Using the Pauling scale.

Question 7

What are the Pauling electronegativity values based on?

Answer 7

The periodic table.

Question 8

What is the pattern with the Pauling electronegativity values?

Answer 8

Electronegativity increases across and up the periodic table.

Question 9

What will happen if the electronegativity difference is large?

Answer 9

The bond will be ionic as the more electronegative atom will have a mch greater attraction for the shared pair of electrons.

Question 10

What is the electronegativity difference for covalent bonds?

Answer 10

0

Question 11

What is the electronegativity difference for polar covalent bond?

Answer 11

0 to 1.8

Question 12

What is thee electronegativity difference for an ionic bond?

Answer 12

Greater than 1.8

Question 13

What happens in a non-polar bond?

Answer 13

The bonded electron pair is shared equally between the bonded atoms.

Question 14

What makes a bond non-polar?

Answer 14

The bonded atoms are the same or the bonded atoms or the bonded atoms have the same or similar electronegativity.

Question 15

What is meant by the term pure covalent bond?

Answer 15

The bonded atoms come from the same element and the electron pair is shared equally.

Question 16

Which two elements form pure covalent bonds and have very similar electronegativity?

Answer 16

Carbon and hydrogen

Question 17

What happens in a polar bond?

Answer 17

The bonded elecron pair is shared unequally between the bonded atoms.

Question 18

What is a dipole?

Answer 18

The separation of opposite charges.

Question 19

What is a permanent dipole?

Answer 19

A dipole in a covalent bond that does not change.

Question 20

Is there only ever one polar bond?

Answer 20

No, molecules containing more than two atoms can have more than one polar bond.

Question 21

What might happen if there is more than one polar bond in a molecule?

Answer 21

The dipoles may reinforce each other to create a larger dipole over the whole molecule, or cancel each other out if the dipoles act in opposite directions.

Question 22

Give an example of a polar molecule.

Answer 22

H2O

Question 23

In water, what do the two O-H bonds have?

Answer 23

A permanent dipole each.

Question 24

What do the two dipoles do in water molecules?

Answer 24

They act in different directions but do not exactly oppose each other.

Question 25

What is the charge of the oxygen atom in a water molecule?

Answer 25

Delta -

Question 26

What is the charge of hydrogen in a water molecule?

Answer 26

Delta +

Question 27

Give an example of a non-polar molecule?

Answer 27

CO2

Question 28

What do the two C=O bonds have?

Answer 28

A permanent dipole.

Question 29

What do the dipoles in CO2 do to each other?

Answer 29

They act in opposite directions and exactly oppress each other, making the molecule non-polar as the dipoles cancel each other out.

Question 30

What is the overall dipole of a non-polar molecule?

Answer 30

0