Hydrogen Bonds can only occur between two polar molecules. Why?
a pH buffer helps to keep a solution's pH stable by neutralizing excess hydrogen ions or hydroxide ions.
When an acid (pH < 7) is added to a buffer, the buffer neutralizes the excess hydrogen (H) in the acid, decreasing the concentration of those hydrogen ions.
When a base (p[H >7) is added, the
buffer neutralizes the excess hydroxide (OH) ions.
Buffers are made up of a weak acid and its conjugate base, or a weak base and its conjugate acid.
Acidosis occurs when your body cannot remove acid from your tissues.
Lactic acidosis occurs when too much lactic acid builds up in your blood.
Diabetic acidosis occurs when too many ketone acids build up in your blood.
Without enough insulin (diabetes) wnich allows cells to utilize glucose for "food", the body begins to break down fat instead of glucose. This causes a buildup of acids in the bloodstream called ketones
Renal tubular acidosis occurs when your kidneys retain too much acid and that acid
is returned to your blood.
Respiratory acidosis occurs when your lungs don’t get rid of enough CO2. CO2 concentration affect pH.
CO2 + H2O ---> H2CO3 ---> H+ + HCO3-
There can be strong or weak acids and bases...
HCl is a strong acid because it dissociates almost completely in water releasing H+.
Acetic acid (CH3COOH...vinegar is 6% acetic acid in water) is a weak acid because it does not dissociate well in water.
Bases containing OH- are considered strong, like NaOH, because they also dissociates almost completely water but they release OH-. what does that do to the pH? Why?
in an aqueous solution,
as H+ concentration increases, OH- concentration decreases.
Bonding Types:
Ionic Covalent Hydrogen
fyi...
It is important for cells/tissues maintain pH homeostasis.
The pH of the human body ranges between 7.35 to 7.45, with the average at 7.4
is it just about H+?
isotopes are variations of elements that have the same number of protons but different numbers of neutrons.
btw...
Electrons carry a negative charge = 1.6 × 10−19 coulombs.
(Coulombs are the basic unit of electric charge 1 amp/sec.)
The mass of an electron = 9.1093837015 × 10−31 kg. Yikes that's teensy. It's only 1/1,836 the mass of a proton.
Oxygen is more electronegative (higher affinity for electrons) than Hydrogen so electrons are unevenly shared, spending more time in the electron cloud around the Oxygen nucleus than the Hydrogen resulting in a polar covalent bond. This causes Oxygen to exhibit a partial negative charge the the Hydrogen to exhibit a partial positive charge.
since we're talking about the concentration of H+,
is 10*-4 (or 1/10,000
or 1 per 10,000)
a larger or smaller concentration than 10*-2 (or 1/100 or 1 per 100)?
10*-4 equates to pH 4
10*-2 equates to pH2
isotopes
buffers
help maintain equilibrium in a solution
Polar
Hydrogen bonds are strong intermolecular forces created when a hydrogen atom bonded to an electronegative atom (polar covalent bond) is attracted to a nearby electronegative atom.
pH
Na (sodium) atomic number = 11
Cl (chlorine) atomic number = 17
Carbon
btw...
The isotope with the longest known half-life is
tellurium-128, with a half-life of 2.2 septillion years.
SEPTILLION!!!
fyi...
Hydrogen Bonds
Properties of Water
btw...
an atom of C14 decays into an atom of 14N. one of the neutrons in the carbon atom becomes a proton increasing the number of protons in the atom and creating a nitrogen atom rather than a carbon atom.
An element's atomic number (#protons/# electrons) is the number listed here at the upper left of each symbol. The atomic mass (#protons + # neutrons) is the number listed below the symbol. Carbon (C) has an atomic number or 6 and an atomic mass of 12.01
Why not 12?? We'll answer this next class...
What do the pH numbers really mean?
and if that homeostasis goes wonky...
Carbon-14
is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons. Every 5,730 years, the radioactivity of carbon-14 decays by half which is called its half-life, a fact used during
Carbon Dating.
Ionic Bonds
what's a buffer?
General Chemistry
Hydrogen bonds have about a tenth of the strength of an average covalent bond
The outermost orbital shell of an atom is called its
valence shell, and the electrons in the valence shell are valence electrons. Valence electrons are the highest energy electrons in an atom and are therefore the most reactive.
next up...biologically relevant molecules ;)
Electron orbitals (identified via quantum mechanics)
predict where an electron might be at any given time. The number of orbitals increases as the atomic number increases.
Covalent Bonds
Welcome to Dr. Kate Brilakis' Learning Portal
The pH scale measures how much H+ is in a solution.
A lot of Hydrogen = low pH # = an acidic solution = an acid
Less hydrogen = a higher pH = a basic (alkaline) solution = a base
A solvent is a substance that dissolves solute particles.
A solute is a substance that is dissolved by a solvent.
remember, a negative exponent
= a fraction ex. 10*-3 = 1/1000
at pH 7
H+ and OH- concentrations are =
Nonpolar
check out the OH-
which is an hydroxyl group
chemistry review questions:
1. describe the structure of an atom.
2. atoms forming ionic bonds _____________ electrons between one another while atoms
forming covalent bonds _____________ electrons between one another.
3. what is meant by an atom's electronegativity?
4. what makes a covalent bond polar? non polar?
5. why must a polar covalent bond be present in order to form a hydrogen bonds?
6. what is an isotope? How might an isotope be used in medicine and science.
7. the formula of water is H2O. How many atoms does one molecule of water contain and how are
these atoms bonded?
8. what does the ph scale describe?
9. what happens to a solution's pH when NaOH is added to the solution? Why?
10. in an aqueous (water) solution, as the H+ concentration increases, the OH- concentration
__________. Why?
11. what is the role of a buffer? How do buffers work?