Bonding: Part 2

Question 1

What is electronegativity?

Answer 1

The ability of an atom to attract the bonding electrons towards itself in a covalent bond

Question 2

In a covalent bond, with identical atoms how are the bonding electrons distributed?

Answer 2

Equally

Question 3

What are non-polar bonds?

Answer 3

When both atoms have the same electronegativity, bonding electrons are evenly distributed between bonded atoms

Question 4

What are polar covalent bonds?

Answer 4

Bonding electrons are more attracted the more electronegative atom. As the electron cloud is more dense around the more electronegative atom there is a permanent dipole across the bond. Polar covalent because of the permanent dipole

Question 5

What is a permanent dipole?

Answer 5

A small difference in electronegativity across a bond resulting from a difference in electronegativities of bonded atoms

Question 6

General trend of electronegativity in periodic table

Answer 6

Increases towards the top right

Question 7

Most electronegative element

Answer 7

Fluorine

Question 8

Covalent bond electronegativity

Answer 8

0

Question 9

Polar covalent bond electronegativity

Answer 9

1.8 ≥ 0

Question 10

Ionic bond electronegativity

Answer 10

≥ 1.8

Question 11

What type of bond do symmetrical molecules contain?

Answer 11

Non-polar, dipoles cancel out

Question 12

What type of bond do non-symmetrical molecules contain?

Answer 12

Polar bonds because the dipoles don’t cancel out

Question 13

What are intermolecular forces?

Answer 13

Attractive forces between molecules that are weaker then ionic or covalent bonds, and only found in covalent structures

Question 14

What are London/induced dipole-dipole forces?

Answer 14

Very weak intermolecular forces between molecules, all covalent structure non-polar or polar

Question 15

How do london forces arise between molecules?

Answer 15

At any moment, there may be an uneven distribution of electrons in a molecule due to movement or change in their density, causing a temporary/instantaneous dipole. The instantaneous dipole in one molecule causes an induced dipole in the neighbouring molecule. Dipoles attract producing weak attractive force

Question 16

What are permanent dipole-dipole interactions?

Answer 16

Weak attractive forces between polar molecules. One of the atoms is more electronegative so a permanent polar bond is present, asymmetry causes them not to cancel out. Dipole attract to produce a weak electrostatic force of attraction between molecules

Question 17

Which is th stronger permanent or induced dipole-dipole attractions?

Answer 17

Permanent dipole-dipoles

Question 18

What are hydrogen bonds?

Answer 18

A strong dipole-dipole attraction between molecules contains O-H, N-H OR F-H. Exists between a H+ dipole atom in one molecule and a lone pair on a highly electronegative atom of another molecule.

Question 19

What type of intermolecular force of attraction is the strongest?

Answer 19

A hydrogen bond

Question 20

Anomalous properties of water

Answer 20

-Ice is less dense than water because molecules are held far apart by the hydrogen bonds, gives ice an open lattice structure. They are fixed in their positions by these H bonds
-Water has relatively high melting and boiling point
-Relatively strong so need lots of energy to overcome