1.1 - The Fundamental Chemistry of Life Flashcards
All ORGANIC COMPOUNDS contain..
CARBON ATOMS and may also contain
HYDROGEN, OXYGEN and NITROGEN
Living thins ARE:
94%:
4%:
0.1%:
94% Carbon, Hydrogen, Oxygen, Nitrogen
4% Ca, P, K, S, Na, Cl, Mg
0.1% Iron and Iodide (Trace Elements)
Atoms are composed of:
Protons (+), Electrons (-), Neutrons (0)
The # of protons determines…
The type of element
ATOMS ARE…
Neutral
Atomic Mass
is the weight of protons and neutrons (electrons have too little of a mass)
What is an ISOTOPE
form of an element that has the
same # of protons but different
# of neutrons
What is a Radioisotope
Unstable isotope that decays giving off radiation
- Transforms into an atom of another element
Example of a Radioisotope
14C is unstable and one neutron splits into an electron and a proton.
When this happens 14C decays into 14N
Radioactive Decay is used for:
- occurs at a steady measurable rate
- used to determine the age of fossils and rocks
Radioactive Tracers are:
using RADIOISOTOPES to trace the path of atoms throughout the body
Ionic Bonds
Form between two oppositely charged molecules
Cation and Anion
Covalent Bonds
Atoms SHARE valence electrons
The strength of the bond depends on the ELECTRONEGATIVITY of the atoms involved
ELECTRONEGATIVITY is…
Measure of an atom’s attraction to shared
electrons
- HIGH E.N. = STRONG attraction of e-
- LOW E.N. = WEAK attraction of e-
Polar Molecules
An unequal sharing of e- due to
different electronegativities results in a polar covalent bond
Generally water soluble
Non-Polar Molecules
Have an equal distribution of charges
The bonds are polar, but the symmetry of the molecule results in a balanced distribution of charges (overall molecule in non-polar)
Generally not water soluble (e.g. oils/fats)
An Atom that attracts electrons more strongly carries a..
partial NEGATIVE charge
An Atom that attracts electrons less strongly carries a..
partial POSITIVE charge
Intermolecular Forces
Attractions that occur between molecules
What are Hydrogen Bonds?
attractive force between slightly positive hydrogen atoms and a slightly negative atom in
another molecule
Hydrogen Bonds are…
strongest and most biologically
significant form of van der Waals forces
- Strong collectively
- Weak by themselves
Hydrogen Bonds are strong when…
- They are in large numbers
- When the temp rises
What are other van der Waal forces?
- Very weak attractions between two molecules when they
are close together - Form from the momentary attractions of electrons to nuclei of other molecules
- Larger molecules have larger forces of attraction than smaller molecules
- Many bonds of this shape can stabilize the shape of a large molecule (e.g. fat)
Dehydration Rxn’s
Removal of water to JOIN two molecules
- One molecule loses a Hydrogen atom while the other loses an –OH group
