Lecture 3 Flashcards
What is a covalent bond
-When two atoms share a valence electron
-strong bond
Why is carbon special
It has 4 valence electrons so it can form 4 different bonds!
Non-polar covalent bond :
Atoms EQUALLY share electrons
What is a polar covalent bond
When atoms share v electrons UNEQUALLY bc they spend more time around one of them (more electronegative)
What is electronegativity
The ability to attract atoms (the more you are the more you attract)
Water is polar -> how is it charged?
Bc oxygen is more electronegative, it is slightly - charged. Hydrogen is slightly + charged
What is the consequence of polar covalent bond with each other?
They attract e/o. (Negative side attracts positive side) this is a hydrogen bond
Hydrogen bond :
When a H atome that is covalently bonded to another bonds with an electronegative atom of another molecule
Hydrogen bonds are weak bc
Easily formed and easily broken when individual (collectively, they can be very strong when in large numbers (ex: dna))
Ionic bonds
Complete transfer of electrons
What are ions
Formed by ionic bonds, cations (+) and anions (-)
Important properties of water :
- Solvent
- Moderation of temperature
- Acids, bases and pH
What makes a solution?
Homogeneous mix of 2/more substances. A solvent and a solute
What is aqueous solution
When water is the solvent
Which substances dissolve well in water
Ionic and polar bonds
Why non polar dot dissolve in water?
Bc they’re not charged, so they stay together whereas charged ones break up with charged H atom from water
Examples of water as solvent in body
-Glucose has OH, water attracted to it
-NaCl
What happens to H bonds when water freezes
Molecules become H bonded creating space between them
What happens to H bonds when ice melts
H bonds become destabilized and molecules pack more closely
When heat is added to water what does it do
It breaks hydrogen bonds first
Why does water resist temperature change
Bc energy needs to be absorbed first to break H bonds and then move molecules
What is water dissociation
Water molecules break into H+ and OH- (same amount of both
What is an acid
Molecule that can release H+ and decrease the [] of OH-
What is a base
Molecule than can accept/combine with H+ and increase [] of OH-
What is a buffer
Substance that minimize changes in [] of H and OH (pH) when acids/bases are added to a solution
How does a buffer work?
Accepts H ions when in excess and donates them when in lack of
Name a buffer important in the body
Carbonic Acid-Bicarbonate buffer system
(H2CO3 <-> H+ + HCO3-)
Why is the carbonic acid bicarbonate buffer system important?
Maintains pH homeostasis of blood
If there is a rise in pH :
Drop in H+ -> need to release H+
If there is a drop in blood pH :
Rise in H+ -> need to remove H+
If there is a drop in blood pH :
Rise in H+ -> need to remove H+
What elements is the human body most composed of
C, N, O, H, Ca
