1C Structure and Bonding

Question 1

What are intramolecular bonds?

Answer 1

Bonds within a molecule.
For example covalent bonds.

Question 2

What are intermolecular forces (bonds)?

Answer 2

Forces of attraction between molecules.
Referred to as Van der Waals forces.

Question 3

Name the 3 types of Van der Waals forces.

Answer 3

1. London dispersion forces (ldf)
2. Permanent dipole to permanent dipole forces (pd:pd)
3. Hydrogen bonding

Question 4

Define the term “metallic bond”.

Answer 4

The electrostatic force between positively
charged ions and delocalised outer electrons.

Question 5

Weak or strong?
Metallic bonds

Answer 5

Strong

Question 6

Weak or strong?
Covalent bonds

Answer 6

Strong

Question 7

Weak or strong?
Ionic bonds

Answer 7

Strong

Question 8

Comment on strength of:
London dispersion forces (LDF’s)

Answer 8

Weakest intermolecular forces of attraction between molecules.

Question 9

Comment on strength of:
Permanent dipole-permanent dipole (pd-pd)

Answer 9

Weak intermolecular forces of attraction between molecules.
(Stronger that LDF’s, weaker than H-bonding)

Question 10

Comment on strength of:
Hydrogen bonding (H-bonding)

Answer 10

Intermolecular force. Stronger than LDF’s and pd-pd.

Question 11

Define the term “ionic bond”.

Answer 11

The electrostatic force of attraction between
positively and negatively charged ions.

Question 12

Ionic compounds conduct when…

Answer 12

Molten or in solution. Not when solid as ions (charged particles) are not free to move.

Question 13

Metallic compounds conduct when…

Answer 13

Solid or molten as delocalised electrons (charged particles) are always free to move.

Question 14

Define the term “covalent bond”

Answer 14

The electrostatic force of attraction between
positively charged nuclei and negatively charged outer electrons.

Question 15

What structure do ionic substances have?

Answer 15

3D Lattice structure.

Question 16

What structures can covalent substances have?

Answer 16

Molecular - H2, CH4, C60.
Network - Diamond, Graphite.

Question 17

Why do Covalent network structures have high mpts and bpts?

Answer 17

Covalent networks have very high melting and boiling points as
many strong covalent bonds need to be broken in order to change
state.

Question 18

Covalent substances do not conduct because…

Answer 18

They have no free moving charged particles.

Question 19

One covalent network substance that conducts is called…

Answer 19

Graphite. It has one delocalised electron per atom that is free to move within the structure.

Question 20

What is polar bonding?

Answer 20

Polar covalent is
formed in compounds between different non-metal elements with different electronegativities.

Question 21

What is non-polar covalent bonding?

Answer 21

Pure covalent bonding is
formed in elements or compounds between non-metal atoms with the same or similar electronegativities.

Question 22

The larger the difference in electronegativity between two atoms means the compound is likely to be….

Answer 22

Ionic in nature.

Question 23

The smaller the difference in electronegativity between two atoms means the compound is likely to be….

Answer 23

Covalent in nature.

Question 24

Permanent dipoles are caused by…

Answer 24

atoms having a significant difference in electronegativity (polar bond) leading to ends being permanently charged.

Question 25

Temporary dipoles are made by…

Answer 25

the continual movement of electrons around the nucleus of an atom, creating temporary areas of slight positivity and negativity.
More electrons in an atom = more dipoles= larger LDF!!

Question 26

When is a molecule with polar bonds not a polar molecule overall?

Answer 26

If there is a symmetrical arrangement of polar bonds, the polarity
cancels out over the molecule as a whole.
E.g. Carbon dioxide, tetrachloromethane.