Bonding

Question 1

What is the definition of a chemical bond?

Answer 1

The attractive forces that holds two or more atoms together in a molecule and it involves valence electrons

Question 2

How to atoms combine to gain stability?

Answer 2

Electrons in atoms distribute themselves in orbitals in the most stable/ lowest energy configuration and rearranging electrons between atoms allows the combined molecule to achieve even lower energy

Question 3

How do we determine the strength of an electrostatic interaction?

Answer 3

• Proportional to the size of the charge

- Inversely proportional to distance squared

Question 4

Explain what is occurring in this graph:

Answer 4

Potential energy curve for the formation of a bond as two atoms approach one another

* Interaction energy 0 means there is no interaction whatsoever (two atoms are far apart)
* >0 means there is an increase in energy (repulsive interaction)
* Decreasing energy levels means the system is becoming more stable (attractive interaction)
* R is the distance between the two atoms or nuclei 
* A minimum energy is reached at around 3.8Å (likely observed bond length)
* If the distance is decreased further, the bond becomes more squashed and the energy of the interaction becomes unfavourable (interaction energy increases rapidly)
* Distance between like charges is becoming very small, so electron clouds are squashed into one another and repelling one another, nuclei are becoming very close together and repelling one another
* Those repulsive interactions very quickly add up and overcome the attractive interactions which were present at that point

Question 5

What is the definition of electronegativity?

Answer 5

The ability of an atom to attract electrons in a chemical bond

Question 6

What does electronegativity depend on?

Answer 6

• Number of protons in the nucleus
• Distance from the nucleus/ size of atom
• Amount of shielding by inner electrons

Question 7

What is the most electronegative element?

Answer 7

Fluorine

Question 8

What is covalent bonding based on?

Answer 8

The polarity of bonds

Question 9

What is ionic bonding based on?

Answer 9

The initial transfer of electrons

Question 10

What is the Pauling scale?

Answer 10

(Electronegativity of elements)

Set of values assigned to electronegativity

Question 11

Describe electronegativity trends in the periodic table

Answer 11

• Electronegativity decreases from right of a period to left of a period and from the top of the group to the bottom
  
  • Atoms in the bottom left of the periodic table have the lowest attraction for electrons
  • Atoms with high electronegativities form either negative ions or form covalent bonds with other similar elements
  • Fluorine is very small with a high charge density in the nucleus, it’s highly reactive
    Chlorine, Oxygen and Nitrogen are also highly electronegative elements

Question 12

Explain this graph linking electronegativity and type of bonding:

Answer 12

• This diagram relates the type of bonding you will see to different elements
  
  • When both elements have low electronegativity they form metallic bonds
  • When both elements have high electronegativity they will form covalent bonds (the elements will share the electrons)
  • As this difference starts to increase you will get polar ionic bonds
    Elements with a large difference in electronegativity form ionic bonds