Lecture 3

Question 1

What is a covalent bond

Answer 1

-When two atoms share a valence electron
-strong bond

Question 2

Why is carbon special

Answer 2

It has 4 valence electrons so it can form 4 different bonds!

Question 3

Non-polar covalent bond :

Answer 3

Atoms EQUALLY share electrons

Question 4

What is a polar covalent bond

Answer 4

When atoms share v electrons UNEQUALLY bc they spend more time around one of them (more electronegative)

Question 5

What is electronegativity

Answer 5

The ability to attract atoms (the more you are the more you attract)

Question 6

Water is polar -> how is it charged?

Answer 6

Bc oxygen is more electronegative, it is slightly - charged. Hydrogen is slightly + charged

Question 7

What is the consequence of polar covalent bond with each other?

Answer 7

They attract e/o. (Negative side attracts positive side) this is a hydrogen bond

Question 8

Hydrogen bond :

Answer 8

When a H atome that is covalently bonded to another bonds with an electronegative atom of another molecule

Question 9

Hydrogen bonds are weak bc

Answer 9

Easily formed and easily broken when individual (collectively, they can be very strong when in large numbers (ex: dna))

Question 10

Ionic bonds

Answer 10

Complete transfer of electrons

Question 11

What are ions

Answer 11

Formed by ionic bonds, cations (+) and anions (-)

Question 12

Important properties of water :

Answer 12

1. Solvent
2. Moderation of temperature
3. Acids, bases and pH

Question 13

What makes a solution?

Answer 13

Homogeneous mix of 2/more substances. A solvent and a solute

Question 14

What is aqueous solution

Answer 14

When water is the solvent

Question 15

Which substances dissolve well in water

Answer 15

Ionic and polar bonds

Question 16

Why non polar dot dissolve in water?

Answer 16

Bc they’re not charged, so they stay together whereas charged ones break up with charged H atom from water

Question 17

Examples of water as solvent in body

Answer 17

-Glucose has OH, water attracted to it
-NaCl

Question 18

What happens to H bonds when water freezes

Answer 18

Molecules become H bonded creating space between them

Question 19

What happens to H bonds when ice melts

Answer 19

H bonds become destabilized and molecules pack more closely

Question 20

When heat is added to water what does it do

Answer 20

It breaks hydrogen bonds first

Question 21

Why does water resist temperature change

Answer 21

Bc energy needs to be absorbed first to break H bonds and then move molecules

Question 22

What is water dissociation

Answer 22

Water molecules break into H+ and OH- (same amount of both

Question 23

What is an acid

Answer 23

Molecule that can release H+ and decrease the [] of OH-

Question 24

What is a base

Answer 24

Molecule than can accept/combine with H+ and increase [] of OH-

Question 25

What is a buffer

Answer 25

Substance that minimize changes in [] of H and OH (pH) when acids/bases are added to a solution

Question 26

How does a buffer work?

Answer 26

Accepts H ions when in excess and donates them when in lack of

Question 27

Name a buffer important in the body

Answer 27

Carbonic Acid-Bicarbonate buffer system
(H2CO3 <-> H+ + HCO3-)

Question 28

Why is the carbonic acid bicarbonate buffer system important?

Answer 28

Maintains pH homeostasis of blood

Question 29

If there is a rise in pH :

Answer 29

Drop in H+ -> need to release H+

Question 30

If there is a drop in blood pH :

Answer 30

Rise in H+ -> need to remove H+

Question 31

If there is a drop in blood pH :

Answer 31

Rise in H+ -> need to remove H+

Question 32

What elements is the human body most composed of

Answer 32

C, N, O, H, Ca