chapter 24 Flashcards
what is the atom
the basic building block of matter, representing the smallest unit of a chemical element
what are the subatomic particles
protons, neutrons and electrons
where are protons and neutrons located in an atom
nucleus
where are electrons located in an atom
outside the nucleus in the orbitals
what are compounds
atoms of more than one element
are atoms created or destroyed in a chemical reaction
No, they are separated combined or rearranged
mass of 1 proton
1 unified atomic mass unit (amu, u) =1 da
do protons and electrons weight he same
No protons are 1840x greater than electrons
what is the atomic # equal to
protons
mass of 1 neutron
1 da or 1 u
different isotopes have different number of what
neutrons
true or false the charge of protons and electrons are equal in magnitude but opposite in sign
true
valence electrons
electrons farthest in the electron shell
does attraction between the nucleus and the e increase or decrease in the valence electrons
decrease
what determines the reactivity of an atom
the valence electrons and their activity
what is an ion
the loss or gain of an e
what is the atomic mass number A equal to
total # of nucleons ( protons and neutrons-
what is the molecular weight
the weight in grams per 1 mole of a given element (g/mol)
what is avogadro’s number
6.02x1023 particles/mol
what is the standard atomic weight
a weighted average of all the isotopes of an element found naturally on earth
who is Ernest Rutherford
provided experimental evidence that an atom has a dense positively charged nucleus that accounts for only a small portion of the volume of atom
who is Max planck
developed the first quantum theory proposing that energy emitted as electromagnetic radiation from matter comes in discrete bundles called quanta
what is the equation of the energy value of a quantum
-eqn E=hf
h= Planks constant =6.626x10-34Js
f=frequency
what is the Bohr H model
- consisted of a central proton around which an electron traveled in a circular orbit and that the centripetal force acting on the electron as it revolved around the nucleus was the electrical force between the positively charged proton and the negatively charged electron
what 2 ideas did Bohr combine to get the energy of the e
quantum theory of plancks and classical physics
what is the equation of the energy of electron
- E=-RH/n2
o RH is constant called Rydberg energy
what causes the Electron energy to change
n=principal quantum number
is the energy of an electron is quantized
true
what are some characteristics of electrons using the Bohr model
- The energy of the electron is related to its orbital radius: the smaller the radius the lower the energy state of the electron
- The smallest orbit (radius) an electron can have corresponds to n=1 which is the ground state of the H electron
- The ground state level the electron is in its lowest energy state
at what temperature is majority of atoms in a sample are in the ground state
room temperature
how can electrons be excited
by heat or other energy to yield the excited state of the atom
what is released when an excited electron returns to ground state
energy in the form of photons
what is the equation for the electromagnetic energy of photons
E=hc/wavelength
H= plancks constant
C=velocity of light in a vacuum =3.00x10^8 m/s
Wavelength of radiation
what is the light spectrum
the spectrum quantized energy of light emitted does not produce a continuous spectrum but at is composed of light at specific frequencies
-Each line on the emission spectrum corresponds to a specific electronic transition
what is the Atomic emission spectrum
ach element can have its electrons excited to different distinct energy levels so each element has its own atomic emission spectrum
what are the Lyman series
n>1 n=1
spectrum region is ultraviolet
what are the Balmer series
n>2 n=2
spectrum region visible and ultraviolet
what are the Paschen series
n>3 n=3
spectrum region infrared
what does this equation represent
–> E=hc/wavelength=-RH (1/ni2-1/nf2)
The energy of the emitted photon corresponds to the precise difference in energy between the higher-energy initial state and the lower-energy final state
When an electron is excited to a higher energy level it must absorb what
energy
The most important difference between the Bohr model and modern quantum mechanical model
Bohr assumption that electrons follow a circular orbit at a fixed distance from the nucleus is no longer considered valid rather electrons are described as being in a state of rapid motion within regions of space around the nucleus called orbitals
Heisenberg uncertainty principle
it is impossible to simultaneously determine with perfect accuracy the momentum ( defined as mass x velocity) and the position of an electron
Modern atomic theory states that any electron in an atom can be completely described by 4 quantum numbers: what are they
n,l,ml, ms
- N=size
- L= shape
- Ml= orientation
Pauli exclusion principle
no 2 electrons in a given atom can possess the same set of 4 quantum numbers
what is the energy state
the position and energy described by its quantum number
what is Principle quantum number (n)
- Positive integer value and represents the shell where an electron is
- The max n that cann be used to describe the electron of an element at its ground state corresponds with that elements period ( row)
what does n say about the energy level and radius of the electron
larger n= higher energy level and radius
does the distance increase or decrease between shells as the distance from the nucleus increases
deceases
what is azimuthal quantum number (angular momentum) (l)
- the shape of the orbitals and refers to the subshells or sublevels that occur within each principle energy level
- for an n the value of l can be integer in the range of 0 to n-1
what are the 4 subshells corresponding to l=0,1,2,3
sharp (s), principle ( p), diffuse ( d), fundamental (f)
the maximum number of electrons that can exist within a subshell is given by the equation?
4l+ 2
what is the Magnetic quantum number (ml)
- the orientation of the orbital in space
- it specifies the particular orbital within a subshell where an electron is highly likely to be ofund at a given point in time
- the possible values of ml are all the integers from l to –l including 0
give the possible values of ml for subshell s
l=0 only has 1 possible value of ml=0 and will contain 1 orbital
give the possible values of ml for subshell p
subshell l=1 has 3 possible values of ml -1,0, 1 and contains 3 orbitals
give the possible values of ml for subshell d
has l=2 has 5 possible ml values and 5 orbitals
give the possible values of ml for subshell f
l=3 has 7 possible values of ml and 7 orbitals
what is spin quantum number (ms)
- the spin of a particle is its intrinsic angular momentum and is a characteristic of a particle
- spin orientations: +1/2 or -1/2
according to what principle must 2 electrons in the same orbital must have opposite spins
- the pauli exclusion principle
parallel spins
electrons in different orbitals ( different ml values) with same ms value
paired spins
electrons with opposite spins ( different ms values) in the same orbital ( same ml)
what is the electron configuration
the first number denotes the principle energy level the letter designates the subshell and the superscript gives the number of e in that subshell
aufbau principle
subshells are filled from lowest to highest energy and each subshell will fill completely before electrons begin to enter the next one
what is the n+1 rule used for
to rank subshells by increasing energy
- this rule states that the lower the sum of the first and second quantum numbers the lower the energy of the subshell
- if 2 subshells possess the same n+l value the subshell with the lower n value has a lower energy and will fill first
what is Hund’s rule
within a given subshell orbitals are filled such that there are a max number of half-filled orbitals with parallel spins
paramagnetic material:
if the material has unpaired electrons a magnetic field will align the spins of these electrons and weakly attract the atom to the field
diamagnetic material
material that have no paired electrons and are slightly replied by a magnetic field
groups IA and IIA only the outermost valence electrons are
s electrons
group IIA through VIIIA the outermost valence electrons are
s and p
transition element the valence electrons are
outermost s subshell and in the d subshell of the next-to-outermost energy and f subshell of the energy shell 2 levels below the outer most shell
true or false atoms with half-filled and fully filled subshells are not extremely stable
false
