MCAT Week 1
There are three subatomic particles - protons neutrons and electrons -
PROTONS -
protons are in the nucleus of an atoms. they have an amount of charge equal to the fundamental unit of charge. +1e
1 AMU - atomic mass unit . The atomic number is Z it is the number of protons in an element - elements are defined by number of protons they contains .
all atoms of an elemtn have the same atomic number.
NEURONS -
neutral - no charge - neyron mass is slightly larger than the proton. So the nuceus has protons and neutrons. atoms have a mass number whihc is the sum of ht eprotons and neutrons o the atomc nucleus. atoms of a lement can have the same atomic number but no the saem mass number. same atomic number and dif mass number is the isotope defintion.
A/z X
a = mass number = protons + neutrons
Z = atomic number = protons
X is the element
ELECTRONS - they move through the space surrounding the nucleus and are associated with different energy levels. Each eelctron has a charge equal in magintiude of a protons but oppposite sign so protons are + and electorns are -e.
mass of electron is 1/2000
electrons closer to the nucleus are at a lower energy level. those that are further are in the higher electron energy. those that are further have a stronger interaction with the surrounding enviorment and the weaker is at the nucleus well closer to. Valence electrons are further form the nucleus - they are the outer most shell.
they are more likely to become involed in bonds with other atoms because they experience the least electrostatic pull from their own nucleus. valence electrons determine the reactivity of an atom. so when the valence electrons shair their electrons iwth other elemnts it increase stability. neutral state there are equal number of protons and electrons losing electrons reults in a atom giaing a postive chage whiel gaininre ults in aotms gaining a negative chaerge. cation is pawsitive and negative charge is an anion
the number of protons and electrons is the same so if there is a 2+ oit just means that it lost two electorns.
IMPORTANT DETAIL
the number of protons and electrons is the same in a neutral atom - if there is a postive or negative it just correlates with the electrons and the number of protons stays the same, if there is a change in atomic mass u subtract the atomic mass by the usualy number of protosn and that is how u figure out the number of neutrons.
what determines the subatomic particle - the charge is related to the elctrons - the atomic number is related to the stupid ahh - protons - the isotpe is related to the neutrons and protons.
the mass of one protons in approxmetly one amu. the size of hte aotmic mass unit is 1/12 of the carbon -12 atom
mass number is the number of protons + nueonons
the atomic mass is the average of all isotopes
the atomic mass is the average of all isotopes -
the mass number is the number of protons + neutrons.
in nature almost all elemnts exsit as two or more isotpes and these are usually present in the same proptions in any samepl of a neutrlaly occuring elemtn - the weighted average of these different isopteis is refered to as the atomic weight and
atomic mass/atomic weight - average of all isotopes
mass number - is just the protons + neutrons.
mole = avogardos number na = 6.02 × 10²3
mole is the number of things
if the atomic weight of a carbon is 12 then that means we multiple that by one mole ————————————-
atomic mass = protons + neutrons of one element
atomic weight is the average of all isotopies
the bohr model of a hydrogen atom is useful for explaining the aotmic emmsion and aborptionspectra of atoms. at room temp the majoring of the aotms are in the ground state.
So at room temp the electrons are excited to higher energy levels by heat or other energy that excites s. the life time of an excited state is briff the electrons will return rapidly to the ground state.
E= hc/
the lowest energy gound state is n=1
so for electrons to make form level to level they have to aborb the right amount of enery to do so. they aborb the energy in the form of light. -
—so the concept summary -
the atomic mass is the sum of an element sprotons and neuotrns.
the p table list the aotmic weight not the atomic masses -
ruthford - atom had a dense postively charge neuclues that made up only a small fraction of the volume of the atom. a psotively charged nucelus is surrdounded by electrons revolign the nulceu with energy levels the difference in energy level is called quantum.
quantaiztion - there is no an infincate range of energy lelvel. electrons can exsist at certain energy levels.
atomic aborbpance elemt i unique for an electorn from lower to higher with the right amounf o energy.
when the elctron returns from the excited state to the ground state they emti an amount of energy that is euqal ot the energy difference bteween the two elelves.
practice problem -
which subtomic particle is detmine each properites of an atomic - the charge is by the electrons the atomicd number is by the protons and the isotpes is by the protons and neutrons
and in the nu
18O = oxygen has 8 protons 8 electrons and and 10 neutrons
18F = 9 protons , 9 electrons, and 9 neutrons.
1.2
atomic mass is the protons and neutrons of a neutral elemnt
atomic weight is the average of all isotopes
molar mass is g/mole but also mol/g wuth conversions
19O = 8 proton 8 eecontr and 11 neutrons
the atomic mass is slighlty
1.3 -
the valence electron in