Bond strength, London forces, dipoles

Question 1

What is an intramolecular force

Answer 1

• forces that occur within the molecule

Question 2

Covalent bond strength is measured by two factors:

Answer 2

1) Number of e‐ shared in the bond

2) Atomic radius

Question 3

Ionic bonds strength is measured by two factors:

Answer 3

1) Atomic Radius

2) Charge

Question 4

How is a covalent molecule held together

Answer 4

by the attraction between the nuclei of both atoms and their shared e‐

Question 5

Covalent bond strength factors

Answer 5

1) The greater the number of e‐ shared = the stronger the
bond between the atoms
2) The closer the atoms are to each other (the smaller
their atomic radius) = the stronger the bond

Question 6

Why do ionic bonds stay together

Answer 6

because of the attraction between the positively and negatively charges ions that are made

Question 7

Ionic bond strength factors

Answer 7

1) The smaller the atomic radius: the closer the
nuclei = the stronger the bond
2) The more charged the ions are: greater
attraction = the stronger the bond

Question 8

Describe melting points in reference to bonds

Answer 8

• The energy that the molecule absorbs does NOT
break the covalent or ionic bond
• The energy actually breaks weaker forces called
LONDON FORCES
• When we melt substances we are not breaking the
covalent or ionic bonds we are breaking weaker bonds
that are called London Forces

Question 9

London forces

Answer 9

• weak electrostatic attractions that hold molecules together
• occur between dipoles
• intermolecular

Question 10

What is an intermolecular force

Answer 10

between the molecules

Question 11

Dipoles

Answer 11

temporary separation of charge within the

molecule

Question 12

Why do dipoles occur

Answer 12

• because there is a slight excess of
the positive charge at one end of a molecule and a slight
excess of negative charge at the other end of the
molecule
• The constant movement of e‐ in the atom creates the
separation of charge

Question 13

Describe the strength of London forces

Answer 13

• Dipoles are reliant on separation of charge between
the charges in the molecule
• The more e‐ there are in an atom: the stronger the
dipole that can occur = strong London Forces
(Large atomic number = Large # of e‐ = Strong London Forces)

Question 14

Describe what happens with the negative ion charges

Answer 14

• Negative ions have gained electrons which increases the number of (‐) charges floating around the atom
• Like charges repel each other, therefore the (‐) charges
will repel one another
• The increased number of e‐ increases the amount of
repulsion in the outer orbital
• e‐ will try to get away from each other because of the
repulsion

Question 15

What are negative ions sizes in contrast to a neutral atom

Answer 15

negative ions are larger than the neutral atom

Question 16

Describe what happens with the positive ion charges

Answer 16

• Positive ions lose e‐, this decreases the number of (‐)
charges in the outer shell, which decreases the e‐
repulsion in the atom
• Because of the e‐ loss, the volume of space occupied by the e‐ has been reduced
• The decreased number of e‐ decreases the amount of
repulsion in the outer orbital
• e‐ are more attracted to the nucleus

Question 17

What are positive ions sizes in contrast to a neutral atom

Answer 17

positive ions are smaller than the neutral atom