Chemistry of life Flashcards
What identifies an element in the periodic table
The number of protons
What is the atomic number?
he number of protons in an element.
mass number?
The sum of the number of protons and neutrons in an atom.
Atoms have volume and mass.
Mass of one proton or one neutron = 1
atomic mass unit (amu) or 1 dalton
1.7 × 10–24 grams.
Mass of one electron = 9 × 10–28 (usually
ignored).
Element
pure substance containing
only one kind of atom.
Elements are arranged in the periodic
table.
Each element has a unique chemical
symbol.
Mass number =
number of protons +
number of neutrons.
mass of atom in daltons
Isotopes:
forms of an element with
different numbers of neutrons, and thus
different mass numbers
Atomic Weight
average of mass
numbers of isotopes in their normally
occurring proportions.
Atomic weight of carbon = 12.011
Atomic weight of hydrogen = 1.0079
What is the role of bicarbonate anion in blood?
It mops up excess acid, helping to buffer the blood
What can carbonic acid be converted to?
Carbon dioxide (CO₂)
What is a buffer
A weak acid/weak base system that resists changes in pH.
What are the components of the buffer reaction shown?
H2O+CO2 ⇌H2CO3
H2CO3⇌H+ + HCO3−
What happens when an acid is added to a buffer solution?
The buffer reacts to minimize changes in pH.
What happens when a base is added to a buffer solution?
The buffer reacts to resist changes in pH.
What does the law of mass action illustrate?
Addition of reactant on one side of a reversible equation drives the system in the direction that uses up that compound
What happens to the reaction when an acid is added?
: It drives the reaction in one direction
base
vice versa
Why are buffers important for life?
They help maintain stable pH levels in biological systems
What is the ionization of strong acids and bases?
irreversible
How is the ionization of weak acids and bases characterized?
Somewhat reversible.
What is the tendency of water regarding ionization
Water has a slight tendency to ionize.
How many water molecules actually dissociate?
1 in 500 million water molecules
ionization of water?
H2O⇌ H+ + OH −
How does water behave in terms of acid-base chemistry?
: Water acts as both a weak acid and a weak base.
ionization of water important for organisms?
Because of the abundance of water in living systems and the reactive nature of the
H
+
ions.
pH?
pH
-Log10[H+]
H
+
H
+
concentration of pure water?
A:
1
0
−
7
M
10
−7
M with a pH of 7.
Q: What does a lower pH number indicate?
A: A higher
H
+
H
+
concentration, or greater acidity.
Q: What is the
H
+
H
+
concentration and pH of a 1 M HCl solution?
A:
H
+
H
+
concentration = 1 M, pH = 0.
Q: What is the
H
+
H
+
concentration and pH of a 1 M NaOH solution?
A:
H
+
H
+
concentration =
1
0
−
14
M
10
−14
M, pH = 14.
