Atoms, Molecules and the Periodic Table Flashcards
Final Exam Content
Atom definition
The smallest unique species of an element.
Atomic scale name
Angstrom
Angstrom value
1 Å = 10^-10m
Prefixes from small things
m = 10^1
mm = 10^-3
μm = 10^-6
nm = 10^-9
pm = 10^-12
fm = 10^-15
Prefixes for large things
m = 10^1
km = 10^3
Mm =10^6
Gm = 10^9
Tm = 10^12
Pm =10^15
Dimensional analysis process
desired unit = current unit x conversion rate.
rearrange the conversion rate so you have a fraction equal to 1.
Substitute in conversion rate.
Why is angstrom used in chemistry
The radius of an atom ranges on the Angstrom scale, which means that chemists get their own unique measuring scale.
Why is dimensional analysis important
It makes transferring between different units easy.
number of atoms in a substance formula
number of atoms = (mass of substance) / (mass of one atom)
Atomic Mass Units (amu) to kg
1amu = 1.661 x 10^-27kg
kg to Atomic Mass Units (amu)
1 kg =6.02 x 10^26 amu
The Avogadro Number
L= 6.02 x 10^23amu
The Avogadro Number definition
The number of species within a mole.
Number of atoms in a substance whole calculation
mass of one atom in kg = RAM amu x 1.661 x 10^-27kg/amu.
# of atoms = mass of substance / mass of one atom.
mass of a proton
1.0073 amu
mass of a neutron
1.0087 amu
charge of a proton
+1.6 x 10^-19C
relative charge = +1
charge of an electron
-1.6x 10 ^-19C
relative charge = -1
nuclide notation
A over Z then chemical symbol
A = mass number
Z = atomic number
mass number
The mass of the protons + the mass of the neutrons.
mass number = 1.0073(#protons) + 1.0087(#neutrons)
atomic number
The number of protons in the nucleus.
RAM of an element calculation
RAM = (%abundance y) x (isotope y RAM) + (%abundance z) x (isotope z RAM)
Isotope definition
An atom of the same element with the same atomic number but a different mass number.
Nuclear binding energy definition
The energy required for the nucleus of one atom to be disassembled into its protons and neutrons.
Nuclear binding energy formula
ΔE = ΔMc^2
ΔM formula
theoretical mass - actual mass
nuclear binding energy whole calculation
Theoretical mass = protons mass + neutrons mass.
ΔM = theoretical mass - actual mass.
Dimensional analysis to convert ΔM from amu to kg.
ΔE =ΔMC^2
Multiply by Avogadro’s Number for J per mol.
energy units
J - joules
1J = 1 (m^2) x kg x (s^-2)
electronic structure stability comparison
electronic structure is less stable than nuclear structure since electrons require less energy than protons or neutrons to cause structural changes.
Changes in electronic structure
Electron energy shell.
Location of electron within an atom.
Which atom an electron is bonded to.
Quantum particles examples
Electrons and Photons
Photons definition
Electromagnetic radiation which behaves with wave-particle duality.
Wave-particle duality
where quantum particles behave as both waves and particles at the same time because of how small they are.
Energy equation for a photon acting as a wave
E = hv
Planck’s constant value
6.626 x 10^-34 Js
energy equation for a photon acting as a particle
E = Mc^2
speed of light
c = 3 x 10^8 ms^-1
ways of describing waves
wavelength
frequency
wavenumber
wavelength
The distance that one period of a wave travels. measured in m. Symbol λ.
frequency
The number of periods of a wave per second.
Measured in s^-1.
Symbol: v.
wavenumber
The number of periods which pass through one cm.
Measured in cm^-1
Symbol: a v with a dash over it.
wavenumber equation
V = 1/λ cm^-1
wave particle duality proof
E=Mc^2 but also E=hv
so Mc^2=hv
v= c/λ
so Mc^2 = hc/λ
Mc = h/λ
This is also true at other velocities.
Mv =h/λ
Mv = p
p =h/λ or λ=h/p
wavelength and frequency formula
c=vλ
v=c/λ
λ = c/v
momentum formula
p =h/λ
momentum = Planck’s constant /wavelength
momentum definition
The mass times the velocity of a particle. (p = Mv)
Heisenberg’s uncertainty principle
ΔxΔp≥h/4π
You don’t need to know this just the rule that you can never know both the exact momentum and position of a quantum particle at the same time.
orbital definition
An orbital describes the area outside the nucleus where there is a high probability of finding an electron.
wave function rule for electrons
When electrons behave like a wave, there is an equal probability of finding an electron at any point with the same amplitude.
what is the use of quantum numbers
To identify and describe any electron within the same atom.
n quantum number
principal quantum number - refers to electron energy shell.
n values
1st shell =1
2nd shell =2 ect
L quantum number
Angular momentum quantum number - refers to the shape of orbital.
L values
L= n-1 maximum
s=0
p=1
d=2
f=3
mL quantum number
the magnetic quantum number - refers to orbital orientation/ the dimension that the orbital lies on.
mL values
mL= [-L,+L]