A la Premed

mSEC is a protein, so therefore it cannot be A and B. It might have some enzyme function, but since mSEC is extracellular when it reaches the osteoblasts, it has little substrates available. Also, an extracellular protein would not make dNTPS (which need to be intracellular).

7-dehydrocholesterol has 7 chiral centers. The number of stereoisomers possible is 2^n, where n is the number of chiral centers. Thus 7-dehydrocholesterol has 128 possible stereoisomers.

Most recently, I have had trouble adapting but am trying to pull through. This pre-medical world is no joke. Although I consider myself a hard worker, it is quite easy to feel somewhat defeated when the majority of your class is achieving great grades. But,again, I will not make a great doctor because of my grades. Yes, there will always be people that are producing greater results than me, that is life..but I know deep down why I could be such a great doctor,perhaps even better than someone who does have higher stats. Life is not solely based on grades and that, is the hardest part to understand in such a process that instills in your mind that grades are everything. I think i have been backtracking and losing focus of why am I doing this. I need to remember that I am doing this to one day help a family,a child..not to prove that I have higher stats. I am forgetting that you learn so much more when you act with passion,with curiosity, instead of leading with worries due to a letter grade. I need to go back to who i was: essentially losing focus off a letter grade, a stat and instead, focusing on what i am learning to the core… So much more productivity will rise from this passion of learning rather than the passion of wanting to achieve. And that, that is the kind of doctor I want to be. I will not strive to prove my degree but I will strive to maintain excellence in willingness and fighting to find a solution. Now, the trick is to convince myself of how to take this next step. I think I am just going to study with the highest level of efficiency i possibly can and with a high level of passion and curiosity without glancing at grades and just let everything else come naturually. what they say is true- your passion really is fruitful on its own without anything added. I can already see the stress drifting away as I immerse myself into a sea of knowledge that will lead me to my goal. I can see myself less stressed and cheerful as I try to investigate every aspect of what i am studying. Somehow, i will make this work. I will never give up. I will be persistant because THAT is the kind of doctor i want to be. 

Inroduction

     Metabolic Acidosis

Osmosis: Pressure exerted on the membrane due to imblanace of solutions on both sides of the gradient

• Hypertonic Solution:Water is leaving the cell and shrivels up- crenated
• Hypotonic Solution:

The importance of Osmoregulaiton: Life of Cell

1. Concentration is directly proprtional to Transport in Simple Diffusion

Facilitated Diffusion

1. Protein facilitates the diffusion of a substance across a membrane - Passive Movement of Materials with the assitance of a protein! A transport protein is an open channel in the bi-layer that allows entry of material. You cannot move things as fast through proteins as much as lipids because there are less proteins than lipids in the bi-layer. Certain amount of “handling time” to move something across a protein. This handling time is » in a protein than a lipid.
2. Saturated- can only work so fast because there is inhibition

3.8 Composition of Compounds

1. A chemical formula in junction with the molar masses of its constituent elements indicates the relative quantities of each element in a compound.
2. To figure out/express how much of an element is in a given compound- use elements mass percent composition for that compound.
3. Mass Percent Composition= Element’s percentage of the compounds total mass.

3.7 Formula Mass and the Mole Concept for Compounds

Calculating Formula Mass: Average Mass of a molecule(formula unit)

1. Formula Mass is also known as Molecular Mass or Molecular Weight

FM=(#ofatomes of 1st element in chemical formula *atomic mass of 1st element)+(#ofatoms of 2nd element in chemical formula *atomic mass of 2nd element) +…etc

• Example: Formula Mass for CO2 - (o has 2)
• 12.01amu+2(16.00amu) = 44.01amu
• Example: Formula Mass for Na2O (Na has 2)
• 2(22.99amu)+16.00amu= 61.98amu

1. Molar Mass of a Compound
2. Sidenote: An elements molar mass(mass in grams of 1 mol of its atoms is numerically equivalent to its atomic mass)

3.6 Molecular Compounds: Formulas and Names

1. Formula cannot be readily determined from its constituent elements bc the combination of the same elements can form other molecular formulas as well
2. Molecular Compounds are composed of two Nonmetals 
3. Prefix-Name of 1st element-prefix-base name of 2nd element +ide
4. First element in name should be most metal like aka bottom left of periodic table
5. If there is a mono in front of the first element,drop it. Monos in front of second element are there to stay though.

• Example: NO2 Nitrogen Dioxide
• Example: N2O Dinitrogen monoxide
• Example: NI3 Nitrogen Triiodide
• Example: PCL5 Phosphorus Pentachloride

Naming AcidsAcids are molecular compounds that release hydrogen ions(H+) WHEN dissolved in water.

1. They are composed of hydrogen(writtenfirst) and one or more nonmetals(written second).
2. Example: HCL is a molecular compound that when dissolved in water forms H+(aq) and Cl-(aq) ions (Aqueous means dissolved in water). Therfore HCL is an acid when dissolved in water.
3. HCL(g)= Gaseous HCL named Hydorgen Choloride bc it is molecualar compound
4. HCL(aq) = HCL in solution(water) named Hydrochloric acid bc it is an acid
5. Acids: have sour taste and have ability to dissolve many metals.
6. Example: Hydrochloric acid exists in stomach fluids-sour taste is obv in vomit
7. Example: If you put Zinc(Zn) into hydrochloric acid, the H+ions(aq) convert the metal into Zn(2+)(aq)cations

• Naming Binary Acids
• are composed of a hydrogen and a nonmetal
• Hydro - Base Name of Nonmetal+ ic -acid
• Example:HCl -> HydroChloricacid
• Example: HBr -> HydroBromicacid
• Example: HI -> HydroIodicacid
• Example: HF -> HydroFlouric acid
• Naming Oxyacids
• contain hydrogen and oxyanions
• oxyanions- anions containing oxygen and a nonmetal
• Oxyacids area combo of 1 or more H+ions with one oxyanion.
• The number of H+ions depend on charge of the oxyanion.
• Names of oxyacid depend on ending of name of oxyanion.
• oxyanions with -ate - > base name of oxyanion+ic - acid
• oxyanions with -ite -> base name of oxyanion +ous -acid
• Example:HNO3(aq) - Nitric Acid
• Example: H2SO3(aq)- Sulfuourous Acid
• Example:HC2H3O2(aq) - Acetic Acid
• Example: HNO2(aq) - Nitrous Acid
• Example: Perchloric acid - HCLO4

Conceptual Connection: Nomenclature- The compound NaCl3 is named Nitrogen Trichloride but AlCl3 is named Aluminum Chloride. Why?

• NCl3 is composed of 2 nonmetals- forming a molecular compound.- usesprefixes.
• AlCl3 is composed of one metal and one nonmetal forming an ionic compound- does not need prefixes.

3.5 Ionic Compounds: Formulas and Names

1. Ionic compounds occur on earths crust as minerals and also in the food we eat: NaCl,CaCO3,KCl
2. Ionic compounds are very stable bc attractions bw cations and anions are strong and bc each ion interacts with several oppositely charged ions (formula unit collection)in crystalline lattice.
3. In a chemical formula,the sum of the charges of positive ions(cations) must equal sum of charges of neg.charged ions(anions). Formula reflects smallest whole ratio #of ions.

Ionic Compounds can be split into two categories( metal forms one type of ion OR metal forms more than one type of ion)

• Metal in I.C forms only one type of cation:
• Name of Cation(Metal)& Base name of anion(nonmetal)+ ide.
• Example: Pottasium Chloride KCl
• Example: Calcium Oxide CaO
• Example: CaBr2 Calcium Bromide
• Example:Ag3N Silver Nitride
• Example: Rubidium Sulfide Rb2S
• Metal in I.C forms more than one type of cation:
• Name of Cation(Metal)& Charge of Cation(Metal) in Roman Numbers in Parentheses & Base Name of anion(nonmetal)+ ide
• Example:Chromium(III)Bromide -> CrBr3 : Br(- charge)(3 of them) Charge of Cr must be 3+
•  Example: Copper(II)Oxide-> CuO: O has(2- charge) so Cu must have charge of 2+
• Example:PbCl4 -> Cl(-charge)(4ofthem) Pb must be 4+. *Lead(IV)Chloride
• Example: FeS-> S(2-charge) Fe must be 2+. Iron(II)Sulfide
• Example: Ruthenium(IV)Oxide-> O(2-) Ru2O2
• Ionic Compounds Containing Polyatomic Ions
• Name of polyatomic ion is used whenever it comes up. No other rules.
• Example: NaNO2 - NO2(-charge)->Sodium Nitrate
• Example: FeSO4 - SO4(2-charge)-> Iron(II) Sulfate 
• Example: NH4NO3- NH4(polyatomic cation:+charge) NO3(polyatomicanion:-charge)= Ammonium Nitrate

Sidenote: Most Polyatomic Ions are Oxyanions- anions contianing oxygen&other element.

Organization of Polyatomic Ion prefixes:

• ClO-    hypochlorite
• ClO2-    chlorite
• ClO3-    cholarate
• ClO4-    perchlorate
• Example: Li2Cr2O7 Lithium Dichromate
• Example: Sn(ClO3)2 - Tin(II)Chlorate :ClO3(-charge)(2) Need 2 Tins.
• Example: Cobalt(II)Phosphate-Co3(PO4)2 :PO4(3-charge)(2)=(6-) need Co(2+)(3)=(6+)


Hydrated Ionic Compounds

• I.C’s called hydrates contain specific #of h2O molecules associated with each formula unit in the compound. Example: MgSO4 *7H2O= Magnesium Sulfate Heptahydrate.The H2O molecules are waters of hydration and can be removed by heating the compound.
• Hydrate: CoCl2 *6H2O [heating] -> CoCl2 : Anhydrous
• Example: CaSO4 *1/2H2O Calcium Sufate HemiHydrate
• Example: BaCl2 *6H2O Barium Chloride Hexahydrate
• Example:CuSO4 *5H2O Copper(II)Sulfate Pentahydrate

Chapter 3: Compounds

1. How to represent them
2. How to name them
3. How to distinguish different types
4. How to write chemical equations showing how they form/change
5. Quantifying element composition of compound( how much of a particular element is contained in a particular compound)

3.1 Hydorgen, Oxygen and Water

1. Properties of compounds are very different from properties of elements that compose them.
2. When 2 elements combine to form compound, an entirely new substance results.
3. Most substances on earth occur as compounds because free atoms are rare on earth.
4. Compound: Elements combine in definite fixed proprtions. <- Different from a mixture, where proprtions can be whatever. ( Example: Compound of Water( 2H to 1 O), Mixture of Hydrogren and Oxygen( can be any ratio)

 3.2 Chemical Bonds

1. Compounds are atoms held together by chemical bonds.
2. Chemical bonds are the result of interactions between the charged particles[ electrons(-) and protons(+) that compose atoms
3.  Electrostatic forces are responsible for chemical bonding(repel/attract)
4. Types of chemical bonds: Ionic and Covalent

Ionic Bonds- occur between nonmetals and metals and involve the transfer of electrons from one atom to another. Since metals have a tendency to lose electrons & nonmetals have a tendency to gain electrons- when a metal interacts with nonmetal,it can transfer electrons(lose) and give them to nonmetal(gain)..Metal loses electron- acquires a positive charge,becoming cation..Nonmetal gains electron- acquries negative charge,becoming an anion…Opposite charges attract by electrostatic force and form an ionic bond. Result: Ionic Compound. In its solid phase,is composed of a lattice(regular 3 dimensional array of alternating cations and anions)

Covalent Bonds -occur between two or more nonmetals and involve the sharing of electrons. Two nonmetals cannot transfer electrons so they share. Shared electrons interact with nuclei of both atoms-lowering potential energy of system forming colvalent bond. Result: Molecular Compound:composed of individual covalently bonded molecules.

Sidenote: Potential energy of a negative charge is lowest when negative charge is between two postiive charges,allowing it to interact with both(when bond is most stable- lower potential energy) Higher potential energy means less stable atom bc it wants to release energy..

3.3 Representing Compounds: Chemical Formulas and Molecular Models

Types of Chemical Formulas

1. Chemical formula: represents what elements are present in compound and #of atoms/ions in each
2. Chemical formulas usually list the most metallic (positively charged)first followed by less metallic(negatively charged)
3. Empirical Formula: gives relative # of atoms of each element in a compound(ratio)
4. Molecular Formula: gives actual # of atoms of each element in a molecule in a compund  Sidenote: some compounds have the same empiral and molecular formula bc it cannot be made into a smaller ratio aka ( H2O)
5. Structural Formula: uses lines to represent covalent bonds- shows how atoms are bonded to each other, shows shape of molecule and compound

Molecular Models

1. Ball  n stick Models: atoms=balls sticks=chem.bonds -reflect shape of molecule
2. Space-Filling Molecular Models: atoms fill spaces to represent closest visual of reality if it were to visibile size

Sidenote: atoms that compose molecule, length of bonds bw atoms,angles of bonds bw atoms,overall shape =determine properties of substance.Spheres in moelcular models represent electron cloud bc nucleus is much too small to accurately show in model. See table 3.1

3.4 An Atomic Level View of Elements and Compounds

1. Elements- may either be atomic or molecular.

   Atomic Elements - elements exist in nature w/single atoms as their basic units. Example: Helium composed of helium atoms. Iron composed of iron atoms.etc

   Molecular Elements- elements exist as molecules: 2 or more atoms of same element bonded together.Most molecular elements exist as diatomic molecules(H2,N2,CL2 etc). Few molecular elements exist as polyatomic elements (P4,S8 etc).

2. Compounds -may either be moecular or ionic.

         Molecular Compounds- usually composed of 2 or more covalently bonded nonmetals.

          Ionic Compounds - composed of cations(metal) and anions( 1 or more nonmetals). Basic unit of ionic compounds= formula units. Forumula unit: smallest electrically neutral collection of ions.Not specific in the organization of the compound- accomodates itself however possible in order to for a cation to be surrounded by anion or vice versa - not specific in ratios or antyhing.

Sidenote: Many ionic compounds themselves contian ions that are groups of covalently bonded toms with an overall charge. Polyatomic ions: ion composed of 2 or more atoms. charge is for the entire ion. Example: CLO- : - is for the entire ion not just oxygen. This is how it is for all polyatomic ions. Polyatomic ions can be found as a unit in compounds. Example: CaCO3 - CalciumCardbonate NaNO2- Sodium Nitrate.

Conceptual Connection: Ionic and Molecular Compounds

Main difference in bw molecular and ionic compounds: Way they bond!! Molecular compounds contain highly directional covalent bonds,which result in formation of molecules- discrete particles that do not covalently bond to each other.Ionic compounds contain non-directional ionic bonds,which results in formation of ionic lattices- extended networks of alternating cations and anions.