Chemistry Notes in Physiology

Chemistry notes in Physiology:

Atoms

Atom—the basic unit of an element

• An atom consists of subatomic particles:

• Proton
• This has a ( + ) charge
• The number of protons in an atom is called atomic number
• Neutron
• This has no charge
• Electron
• This has a ( – ) charge
• The number of electrons is usually equal to the number of protons

• Both the proton and the neutron are in the nucleus
• The sum of the proton and neutron is called atomic mass

• Shell = energy level
• 1st shell has 2 electrons
• 2nd shell has 8 electrons
• Valence electrons are the outermost electrons

• Isotopes = same atomic number, but different atomic mass
• Isotopes will differ in the number of neutrons

• For example:
• Hydrogen has 1 proton
• Deuterium has 1 proton and 1 neutron
• Tritium has 1 proton and 2 neutrons

• Organic molecules: must contain at least carbon and hydrogen
• C-Carbon, H-Hydrogen, N-Nitrogen, O-Oxygen, P-Phosphorus and S-Sulfur

• There are commonly present in organic molecules
• These are important elements in physiology

Chemical bonds (chemistry notes)

Chemical bond is when molecules are formed through interaction of valence electrons between two or more atoms
                        It is the # of bonds of each atom by the # of electrons needed.

• Covalent bonds –bond in which atoms share valence electrons
• Nonpolar covalent = the electrons are equally shared between two atoms

• O2 and H2 are non-polar covalent bonds

• Polar covalent = bond formed between 2 different atoms and the electrons are not equally shared

• The electrons pull towards one atom more than the other
• Electronegativity is when electrons are pulled toward one atom
• Water is a good solvent because it is polar
• The electrons are pulled towards the Oxygen from the 2 Hydrogen atoms 

• Ionic bonds
• One or more valence electrons from one atom is donated or completely transferred to another atom
• Ions are atoms with positive (+) or negative ( –) charge

• Cations have overall (+) charge
• This is because the molecule loses an electron
• Anions have overall (–) charge
• They gain electrons
• An anion and cation bond together form ionic compounds
• NaCl is an example

• Ionic bonds are weaker than covalent bonds

• Hydrogen bonds
• Hydrogen atom forms polar covalent bond with an Oxygen or Nitrogen atom (as well Fluorine) 

• Nitrogen or Oxygen are electronegative atoms, and the Hydrogen atom has a weak attraction for the electronegative atom

• Some important points of hydrogen bonds

• Hydrogen bonds are responsible for the folding of long organic molecules such as proteins
• Hydrogen bonds hold two strands of DNA together
• Hydrogen bonds are formed between adjacent water molecules

• Van der Waals
• These are the weakest bonds
• They are hydrophobic

Hydrophilic – soluble in water

• Example: glucose, amino acids

Hydrophobic – insoluble in water

• Example: fat, nonpolar molecules, hydrocarbons

pH Scales

Chemistry Notes--Back to Learn Physiology
Chemistry Notes - Back to SG Learn Online