GB1: Chapter 2 Flashcards
Atomic nucleus
protons and neutrons packed tightly at center of atom, is + charged due to protons
common elements of human body
carbon, nitrogen, hydrogen, oxygen, potassium, phosphorus, magnesium, calcium, chlorine, sodium, sulfur
compound
2 or more elements combined in fixed ratio
electron cloud
electrons rapidly move about the nucleus, forming a cloud of - charge
Electron orbitals
3D space where electron is found 90% of the time
No more than 2 electrons occupy single orbital
In 2nd energy shell, 4 orbitals can hold up to 8 electrons (2s & 2p = 8 electron spaces)
electron shell
fixed energy shell, electron’s state of potential energy
electrons absorb/gain energy:
electrons lose energy:
the amount of energy gained/lost:
increase in energy level (further away from nucleus)
decrease in energy level (closer to nucleus)
equals the amount of energy between shells
elements
pure substances, cannot be broken down into other substances
energy
capacity to cause change
every electron shell has electrons at certain energy level that are distributed among…?
specific number of orbitals of certain size and orientation
how does atom stay together?
attraction between the +charged nucleus and -charged electrons
in chemical rxns, what is involved?
valence electrons are directly involved, chemical bonds are being broken/formed
inert elements
chemically nonreactive elements that have complete valence shell
matter
anything that has mass and takes up space, made up of elements
molecules
2 or more atoms covalently bonded together
potential energy
energy that matter has due to its location or structure, energy locked into structure-not currently changing
matter naturally moves toward the lowest possible state of potential energy (nelsen’s law #2!)
subatomic particles
these make up an atom
proton +
neutron no charge
electron -
trace elements w/ example
elements required by organisms in minute quantities (less than 0.01% mass) ex: fluorine, boron
valence shell, what does it determine?
outermost shell of electron, it determines the chemical behavior of atom
atomic number
of protons
of protons = # of electrons in neutral atom
Atomic mass (3)
atom’s total mass, weighted average of isotopes, can be estimated by mass number (# protons + # neutrons)
change in proton # = different element
change in neutron # = isotope of element
unit of measurement is DALTONS
isotopes
Atoms of element that have different number of neutrons (different atomic masses)
radioactive isotopes
nucleus decays spontaneously and gives off particles and energy. unstable, so goes to lowest energy level for stability - nelsen’s law #2!
when this changes the # of protons, atom changes to different element
Parent isotope decays into its daughter isotope at fixed rate
radioactive tracers
diagnostic tools in medicine: radioactive isotopes are incorporated into biologically active molecules used as tracers to track atoms during metabolism
also used with sophisticated imaging instruments
half-life
time it takes for 50% of parent isotope to decay
radiometric dating
process to measure ratio of different isotopes and calculate how many half lives have passed since organism was fossilized/rock was formed
chemical bonds w/ 5 types
attraction between atoms with incomplete valence shells through transfer or sharing of electron(s)
single, double, triple: increase in bond # = decrease in bond length = more energy in bonds
van der waals
hydrogen bonds
ionic bonds
polar covalent bonds
nonpolar covalent bonds
bonding capacity
atom’s valence, maximum # of bonds that atom can form with other atoms to complete octet, corresponds to # of electrons needed to complete valence shell octet
covalent bond
the sharing of a pair of electrons between 2 atoms
nonpolar covalent bonds
EQUAL sharing of pair of electrons between 2 atoms due to relatively equal values in electronegativity
polar covalent bonds
UNEQUAL sharing of pair of electrons between 2 atoms due to large difference in electronegativity, resulting in partial charges (more EN, negative partial charge; less EN, positive partial charge)
electronegativity
attraction of particular atom for electron in covalent bond
more EN = stronger pull of electrons
ionic bonds
bond formation due to ATTRACTION between cation (+charged ion) and anion (-charged ion) because of complete transfer of valence electron(s) from one atom to another (this is due to the extremely great difference in electronegativity)
compounds formed: salts, ionic compounds in 3D lattice
hydrogen bonds
weaker chemical interaction, hydrogen atom that is covalently bonded to an electronegative atom (giving it partially +charge) is ALSO ATTRACTED to another electronegative atom (with partial -charge)
in cells, usually to oxygen or nitrogen
chemical behavior of atom
determined by distribution of electrons in shells, especially in outer shell
atoms with same number of valence shells exhibit similar chemical behaviors
van der waals interactions
weakest interaction; only occurs when atoms and molecules are close together, due to the partially negative positive and negative parts of atom/molecule as electrons aren’t always evenly distributed
molecular shape
depends on position of atom’s orbitals.
size/shape are what determine molecule’s function and how they interact with each other
hybridization
when atom forms COVALENT BONDS, the orbitals in its valence shell undergo rearrangement
1s + 3p of valence shell in covalent bond = 4 hybrid orbitals in teardrop shapes
morphine vs endorphine
have similar effects due to similar molecular structures as they bind to same receptor in brain
chemical equilibrium
DYNAMIC EQUILIBRIUM
forward/reverse rxns occur at same rate, relative concentrations of reactant/product don’t change
more reactant-> produce more products
More product -> produce more reactants
orbitals, electron configuration
electrons occupy opposite regions of atom (because they repel each other)
electron spins must be opposite of each other
electron configuration shows how electrons are distributed in orbitals
reactivity of atom
due to the unpaired electrons in one or more orbitals in valence shell
1s___
1s = orbital
1 = energy shell
s = determines orbital’s shape
s = sphere
p = propellor
chemical reactions
forming/breaking chemical bonds leading to change in composition of matter
all are theoretically reversible
polar covalent bond value
0.4 < EN < 0.7
nonpolar covalent bond value
EN < 0.4
ionic bond value
EN > 1.7
