AP Bio chem background packet

Mn

manganese

Cu

copper

I

iodine

Which six elements make up the majority of all living organisms

CHNOPS: carbon, hydrogen, nitrogen, oxygen, phosphorus, sulfur

essentail elements

needed by organisms to live and reproduce

trace elements

essential elements required in minute quantities

smallest unit of an element

atom

what gives atoms its properties

number of subatomic particles, # of protons determines type of atom/element

Particle size/mass of neutrons, protons, electrons

neutrons: 1 Dalton/amu

protons: 1 Dalton/amu

electrons: negligible mass

location of neutrons, protons, electrons

neutrons: nucleus

protons: nucleus

electrons: orbits around nucleus

how to determine # of protons in an atom

atomic # = # of protons

How do you determine the number of electrons in an atom?

atomic # = # of electrons

How do you determine the number of neutrons in an atom?

mass # - #of protons (aka atomic #)

What is an isotope?

different forms of the same element, different # of neutrons

Why are some isotopes radioactive?

number of neutrons can make it unstable, causes it to spontaneously give off particles/energy

atom vs ion

atom: neutron in charge, same # of electrons and protons

ion: does not have a balanced charge, loses/gains electrons

Anion

negative, gains 1 or more electron

cation

positive, loses 1 or more electron (PAW-sitive)

what happens when electrons gain/lose energy

gain: get excited, e- moves further from nucleus

lose: e- moves closer to nucleus

Valence electrons? Why is the # of valence e- significant?

electrons on the outermost shell, # of valence electrons determine behavior/electronegativity

1st shell: 2 e-

2nd and 3rd: 8 e-

what is electronegativity

atom’s attraction/affinity for electrons, the higher the electronegativity the stronger it pulls e- towards itself

• atoms with valence shells less than 50% full lose e-

2 factors that cause high electronegativity

atoms close to competing valence shells, smaller atoms

intramolecular bonds, what are the 3 types

bonds within the same molecule - polar covalent, non polar covalent, ionic

non polar covalent

shares e- equally, when there is a 0 degrees of difference in electronegativity

polar covalent

doesn’t share e- equally, when there is 1 degree of difference in electronegativity (med-high) or (med-low)

Ionic

transfer of e-, 2 degrees of difference in electronegativity

what are partial charges?

the charges of each individual atom in a polar covalent bond (H2O: both H atoms have a partial positive charge, O has two partial negative charges)

compounds vs molecules

both: two or more atoms bonded

compounds: always 2+ different elements, usually molecules, ionic bond

molecules: one or more than one element, not always compounds, covalent bond

what are intermolecular bonds? what is the main one in AP bio?

bonds between atoms in different molecules, hydrogen bonds

what atoms do hydrogen bonds form between?

partially positive and partially negative atoms (polar covalent bonds)

compare strength of H-bonds to ionic and covalent bonds

weaker than ionic and covalent bonds, strongest intermolecular bond, weaker than intramolecular bonds

emergent properties

properties not found in the original atoms of a molecule

ex. H and O don’t have adhesion, high specific heat, etc. but water does

isomer

molecules with the same molecular formula but different structures

structural isomers

different bonds and arrangement of atoms

cis-trans isomers

same bonds, different arangements

enantiomers

isomers that are mirror images

stereoisomers

isomers where bonds stay the same, arrangements differ (cis-trans and enatiomers are stereoisomers)

how do isomers affect living organisms

isomers will have different functions and effects on organisms

acid

releases H+ ions, increasing H+ concentration, lowering pH

base

accepts H+ ions, decreasing H+ concentration, raises pH

Buffer

substance that minimizes changes in concentration of hydrogen and hydroxide ions

• contains acid-base pair

what does a buffer do when a pH increases/decreases?

increase: hydrogen ion released increasing [H+] lowering pH

decrease: hydroxide ion released lowering [H+] raising pH