Biochemistry unit flashcards
biochemistry
The study of the chemical processes occurring in living matter.
Matter:
anything that takes up space and has mass
Element
a pure substance that cannot be broken down to other substances via chemical reactions (any substance on the periodic table)
Compound
a substance consisting of two or more elements combined in a fixed ratio.
What are some examples of compounds
(CO, CO2, H2O)
Molecule:
a substance in which two or more atoms join together chemically. (
are all compounds molecules?
yes
are all molecules compounds?
no
What are elments composed of ?
atoms
What are atoms composed of?
protons, neutrons, and electrons
Atomic Number:
signifies the number of protons or the number of electrons in a neutral atom
Mass number:
signifies the sum of protons and neutrons
Isotope
ne of several atomic forms of an element, each containing a different number of neutrons and thus differing in atomic mass.
Ion
an atom that has gained or lost electron(s)
Anion
indicate a - charged atom which has lost (an) electron(s)
break down the word anion
an- meaning to go up
cation
indicate a + charged atom which has lost (an) electron(s)
break down the word cation
cat- meaning to go down
polar covalent bond
Unequal sharing of electrons in valence shells
-different charges
What is an example of a molecule with polar covalent bonds?
H2O
Can polar covalent bonds exist between two molecules of the same atomic mass?
no, only non polar covalent bonds can, because they would have the same charge
Non-Polar Covalent
Equal sharing of electrons in valence shells
Ionic Bonds
-gain or loss of electrons from valence shells
-Causes an imbalance in electrical charge
-As a result of this exchange, ions are formed
What charges do non-polar covalent bonds result in?
NO CHARGES, remains neutral
Why does water have unique physical and chemical structure?
Oxygen shares e- unevenly with hydrogen due to its higher electronegativity, causing many polar covalent bonds to form.
in H20, which atoms are cations and which are anions?
the oxygen end of the molecule appears negatively charged while the hydrogen end appears positive
Hydrogen bonding
a weak intermolecular attraction between a water molecule and another water molecule or another polar molecule
Why does hydrogen bonding occur?
because of the polar covalent bonds between hydrogen and oxygen. This is because since oxygen is positively charged, and hydrogen is negatively charged, the hydrogen atoms are attracted to oxygen atoms on other water molecules.
Why does water exhibit both cohesive and adhesive properties?
polar covalent bonding
Why does water become less dense and expand as it freezes?
hydrogen bonding
Adhesion
-Water molecules stick to other charged particles
What water properties does adhesion enable?
-universal solvent
- capillary action
What are the substances that water and cannot dissolve?
Water dissolves polar solutes.
-Water cannot easily dissolve non-polar solutes
Hydrophobic
Non-polar substances
Hydrophilic
Polar and Ionic substances
Capillary Action
Water adheres to sides of tubes and other charged surfaces, rising against force of gravity
Cohesion
Water molecules stick to themselves
What water properties does cohesion enable?
High Heat of Vaporization
High Surface Tension
Why does water have a high heat of vaporization?
Because water molecules cohere, more energy is required to break them apart
What substances have a low heat of vaporization?
Non-polar substances have less cohesion and hence lower heats of vaporization