Bonding

Question 1

What happened when an atom combines constructively ?

Answer 1

As in bonding interaction, more electron density is concentrated between the nuclei than otherwise, the total energy of the system decreases

Question 2

What is the bond order given by?

Answer 2

Bond order = #e in bonding orbitals- #e in anti bonding orbitals /2

Question 3

Name to different ways that atoms can be bonded together and explain

Answer 3

Primary bonds - strong bonds may be ionic or metallic

Secondary bonds - weak bonds I.e hydrogen

Question 4

When do primary bonds occur?

Answer 4

When electrons are lost or gained so that the outer shell is filled

Question 5

When is minimum energy for bonding

Answer 5

When dU/dr =0 which is when r0=0

And the interacting force between the pair is zero

Question 6

What equation can be used to express the attractive part of the inter atomic potential of a solid

Answer 6

Uattractive=(sum of all)e^2 alpha/4pi emittivity0 r0

Question 7

What is the repulsive part of the inter atomic potential of a solids normal represented as

Answer 7

Urepulsive proportional to 1/r^n

Or
Proportion to EXP(-r/p’)

Question 8

What is Mie potential

Answer 8

Usolid= -N(Ae^2/r0-B/r^n)

Question 9

Name characteristics of ionic bonds

Answer 9

• High strength
• low conductivity
• high elastic modulus
• high melting point

Question 10

What is covalent bonding

Answer 10

A stable configuration is created by sharing elections with neighbouring atoms

Question 11

Name the characteristics of covalent bonds

Answer 11

• Very high elastic modulus
• high strength but also brutal
• high melting point
• low electrical conductivity

Question 12

What happened in Metallic bonding

Answer 12

The electrons are surrendered to a common pool. And become shared by all the atoms in the metal when they give up there electrons the become ions and the ions are held together by electron cloud surrounding them

Question 13

Name the characteristics of metallic bonding

Answer 13

• high strength
• high elastic modulus
• good electrical conductivity
• high ductility
• metallic lustre

Question 14

Explain hydrogen bonding

Answer 14

Strongest form of secondary bonding and is formed from the polar nature of molecules containing hydrogen
The hydrogen side of the atom is more positive than the atom it’s bonding too causing attraction

Question 15

Name the equations to calculate bond energy

Answer 15

Fn=Fa+Fr=0

F=dU/dr

Question 16

Name the equation to calculate stiff ness

Answer 16

S = dF/dr

Question 17

What determine the elastic modulus of a material ?

Answer 17

Bond force

Question 18

What happened when atoms combine destructively?

Answer 18

Anti bonding , the shared density is less electrons are forced closer together in each atom further raising the total energy