Valnce Bond Theory+Hybridization

Question 1

Explain the diffrence between ionic and covalent bond

Answer 1

-covalent bonds have molecular geometry, ionic bonds have crystalline structures
-covalent bond is directional while in the ionic bond atom forms electrostatic bonds in all directions
-covalent bond is very strong and large energy is needd to break it

Question 2

What are 2 theories of bonding that are more advanced than the Lewis model

Answer 2

1.Valenc bond approach-shared e- pairs form bonds between the atoms. A bond arises from the intersection between the atomic orbitals on two atoms to give a bonding orbital that is located between the 2 atoms(bonding orbital contains 2e-)
2.Molecular orbital approach-atomic orbitals combine to form a set of molecular orbitals that are spread out over the whole molecule. Orbitals-delocalized

Question 3

According to valence bond theory, a covalent bond can be formed if?

Answer 3

1. Atomicnorbital of one atom is superimposed by the atomicnorbital of the other atom
2. The total number of e- in two superimposed orbitls can not be higher than 2

Question 4

How many bonds can atom form

Answer 4

Same as number of unpaired e-

Question 5

What is exception to the rule that atoms number of bonds equal to number of unpaired e-

Answer 5

Carbon- 2 unpaired e-;4bonds

Question 6

Explain concept of hybridization

Answer 6

Atoms are able to change the shape and energies of their atomic orbitals so they can increase their opportunities to form bonds
Hybridization involves interaction between the orbitals of the same atom during the formstion of bonds with another atom

Question 7

What is hybrid orbital

Answer 7

It is the result of the linear combination of atomic orbitals of the same atom. They all have the same energy

Question 8

How does a hybrid orbital look

Answer 8

They have the node at the nucleus and contain 2 lobes of different size

Question 9

What properties can empty orbital give

Answer 9

Gives atom an opportunity to form coordinative bond with another atom or molecule that has a lone pair of e-

Question 10

What is hybridization when atom forms 5 covalent bonds

Answer 10

sp³d

Question 11

What is sp³d² and give an example

Answer 11

When atom forms 6 covalent bonds, ex=sulfur

Question 12

What is sigma bond(б)

Answer 12

Strongest type of covalent bond formed by head on overlapping of atomic orbitals because the extent of overlap is maximum

Question 13

What is a п bond

Answer 13

Sideways or lateral overlapping of atomic orbital.

Question 14

Is shape determined by sigma or pi bond

Answer 14

Sigma bonds

Question 15

Is sigma or pi bond stronger

Answer 15

Sigma bond

Question 16

What defined geometry of the molecule

Answer 16

Bond angle

Question 17

What are assumtions of VSEPR theory

Answer 17

1. The atoms in a molecule are held together by pairs of e- known as bonding pairs
2. Some atoms may have pairs of e- that are not involved in bonding and they are called lone pairs
3. On each atom e- pairs adopt a position as far away from one another as possible

Question 18

How should double and triple.bonds be treated when deciding the geometry of the molecule

Answer 18

They should be treated as single bonds

Question 19

Name all geometries

Answer 19

•Sp= No lone pairs, linear
•sp²= no lone pairs-trigonal planar; 1 lone pair=bent/angular
•sp³= 0 lone pairs= tetrahedral; 1 lone pair= trigonal pyramidial, 2 lome pairs=bent/angular
•sp³d=0 lons pairs=trignal bipyramidial, 1 lone pair= sawhorse/seesaw; 2 lone pairs= T shape, 3 lone pairs= linear
•sp³d²= 0 pone pairs=octahedral; 1 lone pair= square pyramidial; 2lone pairs= square planar, 3 pone pairs=T shape; 4 lone pairs=linear

Question 20

Steps to determine molecular geometry from the VSEPR

Answer 20

1. Draw Lewis structure to show covalent bonds and lone pairs and calculate formal charges
2. Calculate number of e- pairs from the central atom(bonding and line pairs)
3. From the number of bonding and line pairs determine the geometry