Atomic structure, Periodic Table, Bonding and Chemical Interactions, and the Gas Phase Flashcards
What is 1 amu (atomic mass unit) in terms of 12-C carbon atom?
1/12 of one 12-Carbon atom
1 proton = 1 amu
How many atoms are in a mole?
6.022 X 10^23 atoms in a mole
How many grams is equal to one mole of amu?
1 g = 1 mol of amu
What is the equation for the energy of quantum? (for a *single photon)
E = hf = h (c/wavelength) = -R / (ni^2 - nf^2)
How is the angular momentum related to the energy level from which the electrons fall in a hydrogen atom?
angular momentum is linearly and directly related to the energy level from which the hydrogen electrons fall. The hydrogen electrons falling from a greater energy level, releases greater angular momentum
How is the wavelength of absorption and wavelength of emission different?
they are the same
What’s Hund’s rule
Maximum number of half filled shells with parallel spins
Paramagnetic vs. Diamagnetic
In a case of a magnetic field with unpaired electrons, a material with unpaired electron will align in the direction of the magnetic field. This is called paramagnetic, (para - side by side the magnetic field).
Diamagnetic: when the material is slightly repelled. The material has paired electrons.
What is effective nuclear charge? How do you calculate Zeff? Why is Zeff special?
What is the trend of effective nuclear charge across the periodic table?
Why is it always less than the total number of protons present?
Which electrons in an atom produce the shielding effect?
The pull felt by the recently added e-, drawn by the protons in the nucleus. The net positive charge felt by the valence electrons. Zeff = Z - S (number of shielding electrons). Zeff is special because it explains all the other trends in the periodic table.
Always less than the actual Z because of shielding from the core electrons
Across the period because of the increase in charge with no increase in shielding effect. Decrease down the group because shielding effect becomes greater
Electrons toward the inner core (non-valence e-) produce the shielding effect. Electrons in the same shell do not produce shielding effects for each other from the attractive pull of the electrons
What is the trend of atomic radius across the periodic table?
Francium has the largest atomic radius
increase down left toward Francium
Is energy absorbed or released during ionization of an atom? In other words, is energy added or released to remove an electron?
endothermic process, you must input energy to remove and electron
What is the trend of ionization energy across the periodic table? What are the exceptions?
Ionization energy generally increases from left to right
Is energy absorbed or released when electron is added?
exothermic process, energy is released once electron is accepted
What is electron affinity?
How can it be measured?
What is the trend across periodic table?
How much electron pair an atom wants
By measuring the released energy once electron is accepted.
Increase toward Fluorine
Relationship between Zeff and Electron affinity (energy released when electron is accepted)?
Greater the effective nuclear charge, greater the energy released when electron is accepted
What is electronegativity and what is its trend?
an attractive force an atom will exert in a chemical bond for electrons
Increase toward Fluorine
How is electronegativity related to ionization energy?
Electronegativity values are directly related to ionization energies
What is coordinate covalent?
When the shared electrons are contributed only by one atom
For an ionic bond to occur, what must be the electronegativity difference?
The electronegativity must be greater than 1.7
Relationship between bond energy and bond strength
positively correlated
What is the equation for dipole moment?
Dipole moment = charge X radius (C*m)
Angles of different molecular geometries:
Linear, Tetrahedral, trigonal pyramidal, bent, trigonal bipyramidal, trigonal planar, and octahedral
Linear: 180 Tetrahedral: 109.5 Trigonal: 120 Trigonal pyramidal: 107 Bent: 104.5 Trigonal bipyramidal 90, 120, 180 Octahedral: 90, 180
Heisenburg’s uncertainty principle
position and momentum of an electron cannot be known simultaneously
Maximum number of electrons allowed in a single atomic energy level in terms of n
2n^2
Ionization energy trend on the periodic table
increase toward F
What’s higher: first or second ionization energy?
2nd ionization energy
angular momentum quantum number
s, p, d, f (0, 1, 2, 3)
Magnetic quantum number
ml; describes the specific orbital the electron is in, orientation (orbital)
Pauling scale of E-: what does it measure?
What is the pauling scale for non-polar, polar covalent, and ionic bonding?
Measures electronegativity
non-polar: less than 0.5
polar covalent: between 0.5 to 1.6
Ionic: 1.7 and up
0-4, fluorine being 4
How is energy of a photon related to speed of the wave, frequency and wavelength in an equation?
E = hf = hc/wavelength
Closer an electron is to the nucleus, the ____ its energy and the more ____ it is held
the closer an electron is to the nucleus, the lower its energy and the more tightly it is held.
The impact of the size of the nucleus on atomic radius
the size of the nucleus has almost zero impact on the “size” of the atom, which is due to the number of electrons.
Equation for photoelectric effect
hf = energy to eject electron + kinetic energy of ejected electron
hf = work function + 1/2mv^2
h(frequncy) = h(initial frequency) + kinetic energy of the electrons.
What is the relationship between the kinetic energy and frequency of incident photons?
What is the threshold frequency?
directly related;
the threshold frequency is the minimum frequency required to remove the electrons from the outer orbits;
First order decay vs. zero-order decay
difference in terms of half-life
First order decay: half life is the same consistently. It takes the same amount of time to decrease the concentration from 50 to 25 and from 25 to 12.5. The rate of change in concentration decreases linearly with time.
Zero order decay: half life decreases linearly with the concentration. So if the concentration decreases by 50% the half life also changes by 50%. The the rate of change in concentration remains constant over time.
What is Planck’s quantum theory?
E = h*frequency
How to wavelength related to mass, and velocity?
inversely related
Wavelength = h/mv
What is the minimum energy required to eject an electron?
aka the work function; energy of photon minus the kinetic energy of ejected electron
h*f - KE = work function
How do you increase the intensity of light to increase energy? How does increasing the wavelength affect the intensity of light?
increase frequency, not wavelength. Increasing the wavelength does not increase the intensity of light or energy
What is a mean free path
Distance travelled by a gas molecule between collisions
Does polarity affect the homogeneity of the gases?
Polarity does not affect homogeneity. Gases mix regardless of polarity. Given time and low temperature, most dense gas will settle at the bottom however.
What is the equation that relates the average translational kinetic energy and the temperature of the gas? Can you use this relationship on any fluids?
The average kinetic energy is 3/2 * R*T
Can be used in any fluid system
Binding energy
Energy needed to break protons and neutrons
Strong nuclear force
Force that keeps protons and neutrons together
Charge of 1e-
1.6 X 10^-19 coulombs
Metals
Large atoms that tend to lose electrons to form positive ions and positive oxidation states.
Atom in a sea of electrons (fluid like nature of valence electrons)
Ductile, malleable, lustrous, thermally and electrically conductive.
Ductility vs. malleability
Stretching vs. Thin strips
Energy of a single photon
Change in energy of photon is
h * frequency
Wave characteristics of electrons and other moving masses
Wavelength = h / mass * velocity
what is the shielding effect?
the balance of the pull from the protons and the repulsion from surrounding electrons resulting in decreased positive charge felt by electrons due to core electrons (non-valence electrons)
What is an ionization energy?
energy released when an electron is ripped off
