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The Chemical Context of Life - Coggle Diagram
The Chemical Context of Life
Organisms are composed of matter.
Matter: anything that takes up space &
has mass
Matter is made up of Elements.
Elements can't be broken down to
other substances by chemical reactions
Examples: Carbon, Oxygen & Gold
Compound: is a substance containing 2 or more elements
combined. Example: Sodium Chloride NaCl
Elements of Life: Only 20-25 percent of elements are essential
(an organism needs to live a healthy life and reproduce.
Just 4 elements (Oxygen, Carbon, Hydrogen & Nitrogen) make up most of all living matter.
Calcium, Phospohrus, Potassium & Sulfur account for the other 4 percent of an organisms mass.
Trace elements: required by an organism in small quantities
ex: Iron is needed by all forms of life some elements are only
required by certain species.
Evolution & Tolerance to Toxic Chemicals
Where over time certain species develop a tolerance
to elements otherwise known as toxic.
Example: Serpentine plant communities
most plants can't survive in these soils, some over time
have adapted to tolerate it.
An elements properties depend on atom structure
Atom: smallest unit of matter that still retains element properties
Atoms contain 3 kinds of sub-particles: Neutrons, Protons & Electrons
Electrons (-) are found surrounding the nucleus,
while Protons (+) & Neutrons (-/+) are found in the center/
nucleus of an atom
Neutron & Proton are almost identical in mass 1 Dalton. For
atoms &subatomic particles we use Dalton as measurement.
Electrons mass is so miniscule its typically ignored.
Atomic mass: tells us the # of neutrons + protons
Atomic #: tells us # of protons & electrons
Element Isotopes: atomic forms of same element with higher mass due to more higher amounts of neutrons
A radioactive isotope is unstable as it has a spontaneous decaying nucleus which can lead to changing of proton qty therefore changing the element leading to biological tracers in medicine.
radioactive tracers are used by injecting radioactive labeled substances and examining tracers excreted in urine or through PET scans
radioactive decay is used to measure dating of fossils by determining ratio of isotopes and calculating how many half-lifes have passed since the fossil formed this is called radiometric dating
Half-life: 50% of the total time a radioactive isotope takes to decay
In chemical reactions it is only electrons are directly involved
electrons are found in electron shells surrounding the nucleus, the further away the higher the energy level is and the higher the potential energy is.
Energy: capacity to cause change
Potential energy: energy possessed by matter due to
location & structure (page 33 in textbook)
electrons can change shell only by losing or gaining energy
equal to the difference in potential energy between the old shell and new shell.
1 shell (closest to nucleus) holds max. 2 shells
2nd shell & beyond holds max 8
Valence shell: Outermost shell containing valence electrons
Although we use shells, electrons are found 90% of the time in a 3D space we termed "orbital", as we never truly know exactly where an electron is at.
If valence shells are complete, then that element is not reactive as it is full and not "needy"
formation of molecules from atoms
& ionic compounds by chemical bonding
caused by sharing (Covalent bond) or transfer of
valence electrons (ionic bond) resulting in atoms
staying close together (chemical bonding)
Hydrogen covalent bonding example in textbook H-H where - represents a single bond between 2 Hydrogens or H:H where : represents valence electrons
Oxygen example uses O=O where = is a double covalent bond
bonding capacity of Oxygen is 2.
bonding capacity of an atom is called it's valence
Atoms in a molecule attract shared bonding electrons. The attractions of a particular atom for the electrons of a covalent bond is called its electronegativity
the more electronegative an atom the more strongly it pulls shared electrons toward itself. Covalent bonds of same element form a "tug-of-war" standoff termed a nonpolar covalent bond.
In a polar covalent bond electrons are shared unequally, depending on the relative electronegativity of the elements.
Example: Oxygen & Hydrogen bond. Oxygen
Example: Oxygen & Hydrogen covalent bond.
O2 has more electronegativity attracting more electrons (-)
giving it a partial negative charge indicated "delta minus" leaving hydrogen as partial positive or "delta plus"
Ionic Bonds occur when two atoms are so unequal in their arrangement that the more electronegative atom steals an electron from the other atom resulting in opposite charged atoms now called "ions"
Positive Ion: Cation
Negative Ion: Anion
Ionic bond: where cations and anions are attracted to each
these ions do not have to acquire their charge by transfer
Example: NaCl where Na's valence electron is transferred
to complete Cl's valence shell making Na the cation and Cl the anion.
environment can affect the strength of ionic bonds.
Dry ionic bonds are so strong while wet ionic bonds are weaker as they are shielded by water molecules.
Ionic bonds created by ionic bonds such as NaCl (table salt) are found in nature usually in the form of a crystal arranged in a 3D lattice Ionic compounds do not consist of molecules.
not all salts are equal in cations or anions example MgCl where Mg loses 2 valence electrons and can form an ionic bond with two Cl anions.
Hydrogen bonds are weak bonds involving hydrogen atom and an electronegative atom
Van Der Waals interactions are individually weak occurring only when atoms and molecules are close together, but lots of these together can be powerful
Ex: These interactions make it possible for lizards to climb up walls! (Pretty cool I always wondered how it was possible :D)
Molecule Shapes determine how molecules interact with each other,
a molecule of 2 atoms is always linear
more than 2 atoms have more complicated shapes
endorphin & opiate examples: both fit into receptors of the brain like a key due to their molecular structure both for the same reason of pain relief.
Chemical reactions: changes in matter due to the breaking of chemical bonds
reactions cannot create or destroy atoms only rearrange
Example of making a chemical bond:
2 hydrogens + an oxygen = an H2O
where the addition side are both reactants, the equal to sign represents a chemical reaction and the opposite side is called the product/ end result of the merging or subtraction of the reactants
By-products can also occur in a reaction just like oxygen in photosynthesis
All reactions are in theory reversible and are indicated usually by opposite headed arrows
Reactions rates are affected especially by concentration of reactant molecules. The more reactant molecules, the faster these reactions occur and the same for products where collisions can occur and offset the formation of reactants.
Eventually the reaction rates equal the rate of the reverse action this is termed "Chemical Equilibrium"
Remember equilibrium here means their concentrations have stabilized at a particular ratio.not that they were equal.
In some reactions all reactants are converted to products