Midterm Deck Flashcards
Chemistry
the study of the properties and transformations of matter and the interactions btwn matter and E
Measurement
using an instrument to quantify property relative to an international standard
SI Units
Base:
- mass (kg)
- length (m)
- time (s)
- amount (mol)
Derived:
- volume (m^3)
- density (kg m^-3)
- E (J kg m^2s^-2)
Trueness
an indication of how close a measurement (or mean of repeated measurements) is to the accepted “true” value
Precision
an indication of how close together repeated measurements are
Accuracy
combination of trueness and precision -> governed by systematic error/bias
Systematic Error
error w/ the system measurement -> can be eliminated
Random Error
noise; human error -> can’t eliminate
Scientific Notation
x.yE^z
Sig. Figs.
- w/in the accuracy of the measurement
- leading 0’s not significant
trailing 0’s sig. unless ambiguous - exact #’s have unlimited sig.figs.
- calculations:
~ multiplication/division -> sig.figs. limited by the factor w/ the fewest sig.figs.
~ addition/subtraction -> limited to the # of decimal places
~ avoid rounding until the very end
~ BEDMAS
Uncertainty
- limits the # of meaningful digits that should be used to express the measured value
- only express the #s that align w/ your uncertainty
Structure of the Atom
massive nucleus containing protons and neutrons w/ e-s surrounding
Atomic Particles
very small particles that are building blocks for atoms -> e-s, protons, and neutrons
Newtonian Mechanics
- macroscopic objects
- deterministic
- observer independent from system
- continuously variable
- 1643-1727
Quantum Mechanics
- Planck, Heisenberg, Schrodinger, Bohr, Einstein
- submicroscopic (e-s, photons)
- probabilistic
- observer entangled in system
- quantized -> “blocky”
- 1900-1920
Wavelength
distance btwn 2 crests/troughs
Frequency
how many waves past a given spot per second
Velocity
the speed of something in a given direction (V = deltaX/deltaT)
Amplitude
halfway btwn the troughs and crests of waves
Diffraction
wave encounters an obstacle/slit comparable in size to its walv., it bends around it
Refraction
- wavl. dependant
- change in direction of wave propaganation due to a change in its transition medium
Interference
- constructive -> when two waves meet in phase
- destructive -> when two waves meet out of phase
Longitudinal Waves
- oscillations of particles are parallel to the direction of propagation
- eg. sound
Transverse Waves
- particles oscillate perpendicularly to the direction of wave motion
- eg. light
Electromagnetic Wave
- coupling of magnetic and electric fields -> waves perpendicular to electric and magnetic fields and each other
- speed of light = (walv.)(freq)
Electromagnetic Spectrum in Order of Decreasing E (inc walv., dec freq)
Gamma rays, x-rays, ultra-violet light,
visible light, infra-red light, microwaves, radio waves, TV waves
Range of Visible Light
- Violet (400nm)
- Blue (450-500nm)
- Green (500-550nm)
- Yellow (600nm)
- Orange (650nm)
- Red (750-700nm)
Photoelectric Effect
- KEmax = eV0 = 1/2MeV^2
- KEmax is independant of the intensity and proportional to its freq. b/c of lights particle and wave like duality
Rutherford’s Experiment
determined structure of the atom by blasting particles at a gold sheet -> some passes through, other bounced off -> nucleus!
Relationship Between Emission and Absorption Spectra of the Elements
- only emits/absorbs ery specific freq’s b/c of the e- rings in an atom
- instantaneous transition
- emission = falling e-s
- absorption = jumping e-s
The Bohr Equation
- N can be 1,2,3,8,….
- Constant is -ive b/c the nucleus is +ive
- Giving the absolute Es of state
- Z = the charge of the nucleus
- This eqtn only holds for systems in which there is one e- -> Can’t quantify the e- e- repulsion if there is more than 1 e- involved -> Only for hydrogenic atoms/ions
- Moving towards 0 energies -> free
Schrodinger Wave Equation
- H hat = Hamiltonian operator -> Set of mathematical operations that rep the total E of the e-
- E = actual E of the e- -> eigenvalue
- Psi = wave function -> Plot of the wave function squared reps the orbital/probability distribution map of the e-
Fish psi^2dT = 1
the probability of finding an electron somewhere in
the universe is 1
n
- principal quantum #
- determines the overall size
- allowed values are 1, 2, 3…
- orbitals w/ higher n values have less -ive Es
- as n inc the spacing btwn E levels decs
l
- angular momentum #
- determines shape of orbital
- allowed values are 0, 1, 2, 3…, (n-1)
- l=0 -> s, l=1 -> p, l=2 -> d, l=3 -> f
Msubl
- magnetic quantum #
- orientation of orbital
- integer values including 0, ranging from -l to +l
MsubS
- spin quantum # = MsubS +/- 1/2
- cannot have 2 e-s of the same spin -> 2 e-s in each orbital
Orbital
a 3D volume of space close to the nucleus in which there is an arbitrarily high probability than an e- can be found
Shaded vs. Unshaded
shaded sides only indicate that in these regions of space psi has opp signs -> not stipulated which are +ive or -ive -> not electrical charges
Ordering of Orbitals in Terms of E
(from most -ive to least -ive)
1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d < 5p < 6s < 4f < 5d < 5f
Shielding
- e- of interest experiences a lower effective nuclear charge b/c it is screened from the nucleus by other e-s whose max radial probability is closer -> interference
- Zeffective = Z-S -> S = screened charge
- degree to which an e- blocks the e- of interest from the +ive charge of the nucleus
Penetration
- the E of the 2s e- is lower than that of the 2p e- b/c the probability of finding the 2s e- very close to the nucleus is higher than that of finding the 2p e- & therefore the effective nuclear charge experienced by the 2s e- is higher than that experienced by the 2p & the 2s is said to “penetrate” the 1s much better than the 2p does -> lil’ bump
Nodes
- surface on which the probability of finding an e- is 0
- # of nodes = n - l - 1
Afbau Principle
only 2 e-s w/ opp spins are allowed in each orbital, occupy lowest level 1st
Pauli Exclusion Principle
- no 2 e-s in an atom can have the same 4 quantum #s
- each orbital can have a max of only 2e-s, with opposing spins
Hund’s Rule
when filling degenerate orbitals, e-s fill them singly first, w/ parallel spins (then pair up w/ opposing spins)
Core e-s
e-s in complete principal E levels and d and f sublevels
Valence e-s
- e-s that are important to chem bonding
- for main-group elements, the valence e-s are those in the outermost principal E level
- for transition elements, count outermost d e-s as valence e-s even though they are not in the outermost principal E level
- chem properties of an element depend on these e-s
- held most loosely due to shielding effect of core e-s
“Periodic” Table
patterns of chemical reactivity
Relationships of Elements in the Same Group on The Periodic Table
- same # of valence e-s
- similar properties
- row # in periodic table = the highest value of n
- the # of columns in a block corresponds to the max # of e-s that can occupy the particular sublevel of that block
S-block
- alkali metals (1) and alkaline earth metals (2)
- far L
P-block
- on the R
- including rows 13-18
- non-metals
D-block
- in middle
- transition block
- metals
F-block
- lanthanoids (above) and actinoids
- uncommonly used
- inner transition elements
Main Group Elements
s and p block elements (except H)
Group 1
alkali metals
Group 2
alkaline earth metals
Group 11
coinage metals
Group 15
pnictogens
Group 16
chalcogens
Group 17
halogens
Group 18
noble gases
Properties of Metals
- lustrous
- solid at room temp (except Hg)
- conductors
- high melting point
Metals Location
everything except H -> staircase line on R begins at boron (B) and extends down to polonium (Po)
Non-Metals
boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te), polonium (Po) and astatine (At) are the elements found along the step like line between metals and non-metals of the periodic table
Effective Nuclear Charge (Zeff)
- Zeff = Z – S
- the charge experienced by the e- of interest (valence), taking shielding into account
- Zeff is less than nuclear charge due to shielding of valence e-s
- determines how easy/hard it is to remove the valence e-s
