Studied by 4 people
Matter
anything that takes up spa
Element
a substance that cannot be further broken down by chemical reactions
Compound
a substance made up of 2 or more elements combined
Which four elements make up 96% of all living matter?
Oxygen, Carbon, Hydrogen, and Nitrogen
Why are these four elements so abundant ?
Few other organisms account for the remaining 4% of an organism’s mass
In which compounds are these elements (O, C, H, N) found?
organic compounds
Essential elements
elements required for an organism to survive grow and \n reproduce.
Trace elements
elements that indispensable for life but required in extremely \n minute amounts.
Atom
smallest unit of matter that retains the properties of an element.
Dalton
a measure of mass for atoms and subatomic particles; the same as atomic mass unit (amu).
radioactive isotope
an unstable isotope whose nucleus spontaneously decays and \n gives off energy and particles
Valence Electrons
electron(s) on the outermost electron shell
Valence shell
the outermost energy shell of an atom containing electrons involved in the chemical reactions of that atom.
Electron orbital
a 3D space where electrons are found 90% of the time.
Chemical bonds
an attraction between two atoms leading to, the two atoms sharing outer-shell \n electrons, or the presence of opposite charges on the atoms
Covalent bonds
the sharing of a pair of valence electrons by two atoms
Molecule
two or more atoms held together by covalent bonds
Electronegativity
the attraction of a given atom for the electrons of a covalent bond
Nonpolar covalent bonds
a type of covalent bond in which electrons are shared equally \n between two atoms of similar electronegativity
Polar covalent bonds
a type of covalent bond in which electrons are shared equally between \n two atoms of differing electronegativity
cation
positively charged ion
anion
negatively charged ion
ionic bond
chemical bond resulting from the attraction between oppositely charged ions
Hydrogen bond
a weak chemical bond formed when a slightly positive hydrogen atom is attracted to \n a slightly negative atom of a polar covalent bond in another molecule or region of the same \n molecule
Van der Waals interactions
weak attractions between molecules of parts of molecules that \n result from ever-changing local partial charges
Why do atoms form bonds?
Atoms bond in an attempt to complete their valence shells.
What determines whether a covalent bond is non-polar or polar?
whether or not the \n atoms bonded have similar or differing electronegativity.
Why are hydrogen bonds not true bonds?
The atoms can come together but separate after affecting each other.
What causes molecules to have different shapes?
Molecules have different shapes due to the positioning of their atoms’ orbitals.
Why is different molecular shapes biologically important?
Molecular shape determines how biological molecules recognize and respond to one another with specificity; Biological molecules only bind if their shapes are complimentary
Chemical reactions
the making and breaking of chemical bonds leading to changes in \n composition of matter.
Chemical equilibrium
the state in a chemical reaction when the rate of the forward reaction \n equals the rate of the reaction in reverse.
What does it mean that a reaction has reached equilibrium?
\n It means the rate of the reaction going forward is equal to the rate of the reverse \n reaction, so the relative concentration of reactants and products don’t change over \n time.
Polar molecule
a molecule with an uneven distribution of charges in different regions.
What kind of bonds link each atom in a water molecule?
Polar covalent
How many hydrogen bonds can each water atom form?
Each water molecule can hydrogen bond with up to four other water molecules
Why is liquid water denser than frozen water (ice)?
Cohesion
the linking together of like molecules, often by hydrogen bonds
Surface tension
a measure of how difficult it is to stretch or break the surface of a liquid
Adhesion
the linking together of different molecules by means of hydrogen bonds
Specific heat:
the amount of heat that must be absorbed/lost for 1g of a substance to change its temperature by 1 degree Celsius.
Heat of vaporization
the quantity of heat a liquid must absorb for 1g of it to be converted from \n liquid into a gas.
Evaporative cooling
the process in which the surface of an object becomes cooler during evaporation as a result of molecules with the greatest kinetic energy changing from a liquid to gas
Hydrophilic
having an affinity for water; if water molecules are too big ma not dissolve
Hydrophobic
having no affinity for water/ tending to coalesce and form droplets in water
What are the four emergent properties of water that are important for life?
Cohesion, Moderation of temperature, Expansion Upon Freezing, Versatility as a Solvent
Does water have a low or high specific heat relative to most other molecules? Why?
Water has a high specific heat is because much of the heat absorbed by water is used to disrupt the hydrogen bonds before water molecules that to move fast enough.
Why is the floating of frozen water important?
The expansion of water upon freezing allow to life to continue under frozen surfaces of lake and polar seas.
Why is water a good solvent?
Water makes a good solvent because its polar molecules it’s attracted to ions and other polar molecules that it can form hydrogen bonds with.
How is hydrogen bonding is important to each of water’s emergent properties?
Cohesion → allows water molecules to drag each other up
Mod. of temp. → water’s resistant to temp. change b/c heat goes towards breaking H bonds
Expansion upon freezing → molecules expand ice as not to break H bonds
Versatility as Solvent → form H bonds with polar/ionic molecules thus separating them
Expansion Upon Freezing
H bonds stabilize in cold temp. and thus can form up to 4 bonds
Organic compounds
the study of carbon compounds
How can only a handful of different elements (e.g. C, H, O, N) form so many different molecules?
Carbon has the ability to form four bonds (the maximum possible), it can form an inexhaustible variety of organic molecules with the handful of major elements (C, H, O, N, S, P).
Hydrocarbon
an organic molecule made up of only carbon and hydrogen
Isomer
one of two compounds that have the same numbers of atoms of the same elements but \n different structures and hence different properties.
Structural isomer
isomers that differ in the covalent arrangement of their atoms
Geometric isomer (cis-trans isomer)
an isomer that has the same molecular formula and covalent bonds between atoms but differ in the spatial arrangements of their atoms owing to the inflexibility of double bonds
Enantiomer
one of two compounds that mirror each other but differ in shape due to the presence of an asymmetric carbon
How can the carbon skeletons differ?
Carbon skeletons can very in length, branching, double bond position, presence of rings, and/or presence of other elements.
Functional group
a specific configuration of atoms commonly attached to the carbon skeletons of organic molecules and involved in chemical reactions
List the 7 important functional groups in biology.
hydroxyl, carboxyl, carbonyl, amino, sulfhydryl, phosphate, methyl
Hydroxyl (OH)
Alcohol
Polar, reactive, forms hydrogen bonds
Carboxyl (COOH)
Carboxyl/organic acid
Polar, reactive, acts as an acid, its ionized form found in cells
Carbonyl (CO)
Ketone/Aldehyde
polar, reactive, sugars
Amino (NH2)
Amine
Polar, reactive, act as a base
Sulfhydryl (SH)
Thiol
Polar, reactive, forms cross-links to stabilize protein structures
phosphate
Organic phosphate
Polar, reactive, contributes to negative charge, releases energy when in contact with water
methyl
Methylated compound
nonpolar, nonreactive, affects expression of genes when bonded to DNA or proteins that do
What is ATP?
An adenine containing nucleoside triphosphate that releases free energy when its phosphate bonds are hydrolyzed.
When ATP reacts with water, it undergoes hydrolysis. What are the products of the \n hydrolysis reaction?
\n ADP (adenosine diphosphate)
Note 
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