essential elements
elements that are required for life (about 20-25% of the 92 natural elements)
what 4 elements make up 96% of living matter?
carbon, hydrogen, oxygen, and nitrogen
what 4 elements make up the other 4% of living matter? (approximately)
calcium, potassium, phosphorous and sulfur
trace elements
elements required by an organism in only minute quantities
True or False: dalton and amu are the same
True
decay
tendency of an atom to lose subatomic particles
radioactive isotope
unstable atom, which has a nucleus that decays spontaneously, giving off particles and energy
what happens when a radioactive isotope decays to the point where it loses a proton?
it transforms the atom into a different element
radioactive tracers
the use of radioactive isotopes as diagnostic tools in medicine
metabolism
chemical processes of an organism
radioactive atoms
cells can use ________ _____ just like non- radioactive isotopes of the same element
why are radioactive isotopes incorporated into biologically active molecules?
to track atoms during metabolism
True or False: tracers CANT be used with various imaging instruments, such as PET scans
False, they can be used
radiation, cellular molecules
although radioactive isotopes are useful in research + medicine, __________ from decaying isotopes is also a hazard to life by damaging _________ _________
radiometric dating
when scientists measure the ratio of different isotopes in fossils / rock and calculate how many half lives have passed since the fossil or rock was formed
energy
the capacity to cause change
potential energy
energy possessed by an object because of its location or structure
why do electrons have potential energy
because they are farther from the nucleus — takes energy to keep electrons far from the nucleus due to the +/- attraction
energy level
the potential energy of an electron is determined by its ______ ______
how can electrons move from one energy level to another?
they can absorb or release an amount of energy equal to the difference in potential energy between the new and old energy levels
distribution of electrons
the chemical behaviour of an atom is determined by the ____________ __ ________ in shells
orbital
3-dimensional space where an electron is found 90% of the time
True or False: matter tends to exist in the highest available state of potential energy
False. matter tends to exists in the LOWEST available state of potential energy
dry ionic compounds
the strongest type of bonds are covalent bonds and ionic bonds in ___ _____ _________.
single bond
sharing one pair of electrons
double bond
sharing two pairs of electrons
valence
an atom’s bonding capacity - usually same as # of unpaired electrons
electronegativity
an atom’s attraction for electrons in a covalent bond (more EN = stronger pull on electrons)
non-polar covalent bond
covalent bond where atoms share electrons equally
polar covalent bond
covalent bonds where atoms share electrons unequally due to the fact that one atom is more electronegative
dipoles
polar covalent bonds cause positive or negative _______ (partial charges) for each atom
ionic bonding
the transfer of an electron from one atom to another, allowing a bond to form between the two
True or False: the transfer of an electron automatically forms an ionic bond
False. the transfer of an electron is not, by itself, the formation of a bond, but instead ALLOWS a bond to form as it results in two ions of opposite charges
covalent bonds
most of the strongest bonds in organisms are ________ bonds forming cell’s molecules
why are weaker interactions crucial to life?
many large molecules need to use weak bonds to be functional as the reversibility of weak bonds allows two molecules to come together, affect one another, then separate again
why is the reversibility of weak bonds advantageous?
allows two molecules to come together, affect one another, then separate
3 types of crucial weak bonds
hydrogen bonds, Van der Waals forces (and LDF), ionic bonds in aqueous solutions
hydrogen bond
bond between a hydrogen atom in a molecule with a positive dipole to a highly electronegative atom in an adjacent molecule
occurs with H, O, F, N (any other w hydrogen, would be a dipole-dipole force)
Van der Waals interactions
attractions between close molecules due to uneven electron distribution in the molecules, forming temporary and/or instantaneous dipoles
Can Van der Waals forces be strong?
individually they are weak, but collectively they can be strong (ex. Gecko’s toe hairs)
size and shape
a molecule’s ____ ___ _____ are key to it’s function
orbitals
a molecule’s shape is determined by the position of its _______
recognize and respond
molecule shape determine how biological molecules _________ ___ _______ to each other
photosynthesis equation
6 CO2 + 6 H2O —> C6H12O6 + 6 O2 + 36 ATP
dynamic equilibrium
when a reaction occurs in both directions, but concentrations of reactants and products are stabilized in a particular ratio
biology department
the study of life
matter
organisms are compose of ______
element
a substance that can’t be broken down to other substances by chemical reactions
compound
a substance consisting of two or more elements in a fixed ratio
atomic number
number of protons in an atom’s nucleus
mass number
the sum of protons and neutrons in an atom’s nucleus
atomic mass
atom’s total mass - can be approximated by the mass number
isotopes
two atoms of an element that differ in the number of neutrons
what can iodine be used to detect in medicine?
thyroid cancer because iodine in needed and used by the thyroid gland
FORM = FUNCTION
slight changes in form, changes function completely in biology
is cellulose polar or non-polar (extra question)
cellulose looks polar because its not symmetrical, but it’s actually non-polar because long chains of it becomes symmetrical
what bond angle does a water molecule have?
104.5º
what shape is a water molecule?
bent or angular
what do enzymes and catalysts do to bonds?
they put pressure on bonds to break them apart (for both weak and strong bonds)
ionic bond
an attraction between an anion and a cation
ionic compound structure
usually a crystalline lattice
chemical reactions
the making and breaking of chemical bonds
reversible
all chemical reactions are ________
what chemical is responsible for “runner’s high” feeling? (extra question)
endorphins