Lecture 1- Hybridization+Bonding

Question 1

What is a molecule?

Answer 1

A group of atoms joined together by chemical bondings

Question 2

What are the two different types of chemical bondings?

Answer 2

1-Ionic bond 2-Covalent bond

Question 3

Explain what a covalent bond is:

Answer 3

Sharing of a pair of electrons between two atoms

Question 4

Explain what an ionic bond is:

Answer 4

Complete transfer of one or more electrons from one atom to another.

Question 5

If a molecule is hybridized sp which shape has it got?

Answer 5

Linear (Angle 180°)

Question 6

If a molecule is hybridized sp2 which shape has it got?

Answer 6

Trigonal planar (Angle 120°)

Question 7

If a molecule is angular what sort of hybridization has it got?

Answer 7

sp3

Question 8

If a molecule is hybridized dsp3 which shape has it got?

Answer 8

Trigonal pyramidal

Question 9

If a molecule is tetrahedral what sort of hybridization has it got?

Answer 9

sp3

Question 10

If a molecule is hybridized d2sp3 which shape has it got?

Answer 10

Octahedral

Question 11

What is the hybridization of CH4, NH3 and H20?

Answer 11

sp3

Question 12

What is the hybridization of ATP?

Answer 12

sp3

Question 13

What is the VSEPR theory? (Valence Shell Electron Pair Repulsion pronounced Ves-pur or ves-seh-per)

Answer 13

It is a theory in chemistry that allows scientists to predict the shape of molecules from determining the number of electron pairs of a molecule

Question 14

What shape is an s-orbital?

Answer 14

Spherical

Question 15

Describe the shape and orientation of the five d-orbitals

Answer 15

4 of the 5 d-orbitals are shaped exactly the same but are orientated differently. The fifth d-orbital has a different shape from the other 4.

Question 16

What’s hybridization?

Answer 16

A change in the shape of atomic orbitals which allows electron to occupy new locations. The results is an hybrid orbital.

Question 17

How are sp3 hybrid orbitals made?

Answer 17

1-First of all, in carbon, an electron from its 2s orbital gets promoted to the unoccupied p-orbital. 2-Then the 2s-orbital mixes with the three 2p-orbitals to form four identical sp3 orbitals. This is why carbon can form four bonds.

Question 18

Bases of DNA and RNA have a ______ shape.

Answer 18

Planar (flat)

Question 19

Why do the bases of DNA and RNA have a planar (flat) structure?

Answer 19

Usually, molecules with N as their central atom adopt a trigonal pyramidal shape but in the case of the bases of DNA and RNA, the nitrogen atoms in the bases donate their lone pairs to the ring structure.

Question 20

What is the difference between intermolecular forces and intramolecular forces?

Answer 20

Intermolecular bonds exist between molecules whereas intramolecular bonds are bonds that exist between atoms in a molecule.

Question 21

Intermolecular forces are ____ than intramolecular forces

Answer 21

Weaker

Question 22

What are the three types of non-covalent forces (Van der Waals forces)?

Answer 22

Dipole/Dipole forces (aka Keesom forces) Dipole/Induced Dipole (aka Debye forces Induced dipole/Induced dipole (aka London dispersion forces for Higher and Advanced Higher chemistry scum)

Question 23

What is a dipole?

Answer 23

A dipole is a separation between two equally but oppositely charged poles or particles.

Question 24

Which intermolecular bond can explain why ammonia, water, and hydrogen fluoride have a higher boiling point than predicted?

Answer 24

Hydrogen bond!!!

Question 25

Which three atoms must be attached to a hydrogen atom to facilitate hydrogen bonding?

Answer 25

N, O, and F

Question 26

Describe induced dipole-induced dipole forces:

Answer 26

Weak molecular interactions that occurs between all molecules.

Question 27

What are the three features of induced dipole-induced dipole forces?

Answer 27

1- They are short lived 2- They are weak 3- They operate over short distances

Question 28

What are the two factors that affect induced dipole-induced dipole forces?

Answer 28

Size (bigger molecules have stronger dipoles because they have more electrons) and shape (Long and thin molecules develop stronger dipoles because the lie more closely).

Question 29

Describe dipole-dipole forces:

Answer 29

The forces that exist between opposite charges on polar molecules (the are permanent).

Question 30

Which very important biomolecules depends on hydrogen bonds?

Answer 30

DNA and RNA.

Question 31

Why is hydrogen bonding so important in DNA?

Answer 31

1-It stabilizes the structure of DNA 2-It allows DNA to be duplicated

Question 32

How many hydrogen bonds exist between A and T and G and C?

Answer 32

A and T - 2 H. bonds G and C - 3 H. bonds

Question 33

What is an hydrogen bond?

Answer 33

A dipole-dipole interaction between an hydrogen and an electronegative atom of N, O or F.

Question 34

What are the two conditions for hydrogen bonds?

Answer 34

1- The hydrogen atom must be bonded to an atom of N, O or F. 2- The hydrogen bond can only be formed between the hydrogen atom and a lone pair of an atom of N, O or F.