L1 L2 Chemical Basis of Life
Matter: has mass and occupy space, made of elements
Atom: smallest unit of matter unique to the part.
Element, retain chem and phy properties.
-
Atoms w/ no octet → reactive → interacting
then form chem bonds
Chemical Bonding
Atomic Structure
Det. behavior of the element.
Subatomic Particle
● Protons (+)
-
Atomic number (Ex: Na₁₁)
Num of protons = num of electrons
● Neutrons
-
Atomic mass
Numbers can vary:
- Isotopes: same atomic number, different
atomic mass. Different isotopes of same
element react same chemically.
- Radioactive Isotope: unstable that emits
nuclear particle/energy, transform to
another element.
● Electrons (-)
-
Orbit the nucleus
Highest potential energy → furthest from
nucleus
Gain or loss energy
Covalent Bond (non-non)
-
Sharing e
Strong chem bond (ex: H₂, O₂, N₂)
Single, double & triple (rigid, no rotation)
Ionic Bond (metal-non)
-
Transfer e (electrostatic attraction)
Forms an ion: cation (+) lose e, anion (-) gain
e
Strong in crystal form but weak in H₂O
Weak Chemical Bonds
Temporary → form reversible bonds → stabilize
tertiary structures of large molecule
- Hydrogen Bonds: H covalently bond to FON.
easily break
- Van der Waals Forces: molecules are close
- Hydrophobic interactions
Water
-
A polar molecule held by hydrogen bonding
Occasionally, H shifts from one O to another.
-
Solute is dissolved in a solvent to make a
solution.
Valence Shell and Valence Electron
-
Valence electron: outermost, det. chem
properties
Octet rule: 8e → unreactive (He, Ne)
Acids and Bases
Acids: in H₂O, donates H+ to solution
Bases: in H₂O, OH- combine with H+, takes out H+
Equilibrium (pure water): [H+] = [OH-]
Acidic: pH < 7
Basic: pH > 7
Most biological systems 6-8 (except stomach),
maintained by a buffer system
Carbon
-
Primary cellular composition
Able to form large molecules
Contain C → organic molecules
More versatile, 4 valence e, rings and others
C-C combinations introduce complexity and
variety
Organic molecules with C and covalently bonded
vary in length, shape, num and loc of double
bond
Functional Groups
A num of small groups of atoms freq. bound to C
- Specific chem and phy properties
- Chemically reactive
- Num and arrangement det. unique chem
properties
Types:
1. Hydroxyl group (-OH): alcohols
2. Carbonyl group (CO-): aldehyde or ketone
3. Carboxyl group (-COOH): carboxylic acids
4. Amino group (-NH₂): amines
5. Sulfhydryl group (-SH): thiols
6. Phosphate group (PO43-): cellular energy
storage
7. Methyl group (-CH₃): tertiary structure of
macromolecules
Macromolecules (Polymers)
Polymerization: the process of forming
macromolecules. Condensation reaction that links 2
or more small molecules through formation of
covalent bonds, removing 1 H₂O per covalent bond
formed.
Hydrolysis → break covalent bond by adding H₂O