Chem Flashcards
Mass number
The sum of protons and neutrons
Atomic weight
The weighted average of different isotopes reported on the periodic table
Equation for energy of a quantum
E=hf; E=hc/λ; E=hv/λ
*Positive E corresponds to emission, negative E corresponds to absorption
Equation for angular momentum
L=mvr
Equation for angular momentum of a hydrogen electron
L=nh/2π
Equation for energy of an electron
E= -R(H)/n^2
R(H)=2.18*10^-18 J/electron
*Energy (E) is directly proportional to principal quantum number (n)
Speed of light, c
3*10^8 m/s
Atomic number
Number of protons
Planck’s constant
h=6.626*10^-34 Js
Lyman series
The group of hydrogen emission lines corresponding to transitions from energy levels n≥2 to n=1
Balmer series
The group of hydrogen emission lines corresponding to transitions from energy levels n≥3 to n=2
Paschen series
The group of hydrogen emission lines corresponding to transitions from energy levels n≥4 to n=3
Heisenberg uncertainty principle
It is impossible to simultaneously determine, with perfect accuracy, the momentum and the position of an electron
Pauli exclusion principle
No two electrons in a given atom can possess the same set of four quantum numbers
Principle quantum number (n)
The larger the integer value of n, the higher the energy level and radius of the electron’s shell
*Also tells you the possible number of subshells (l)
Maximum number of electrons within a shell
2n^2
Equation for energy of a quantum
E= -R(H)*[(1/ni^2)-(1/nf^2)]
*The difference in energy between two shells decreases as the distance from the nucleus increases because the energy difference is a function of [(1/ni^2)-(1/nf^2)]
Azimuthal quantum number (second quantum number, l)
Shape and number of subshells within a given principal energy level (shell)
*For any [rincipal quantum number (n), there will be n possible values for l, ranging from 0 to (n-1)
Maximum number of electrons within a subshell
4l+2
l= Number of subshells
Magnetic quantum number [third quantum number, m(l)]
Specifies the particular orbital within a subshell where an electron is most likely to be found at a given moment in time
*Possible values range from (-l to +l) where l= the number of subshells
Spin quantum number [fourth quantum number, m(s)]
Refers to the two spin orientations that apply to an electron, +1/2 and -1/2
*Two electrons in the same orbital must have opposite spins
Aufbau principle (building-up principle)
Each subshell will fill completely before electrons begin to enter the next one
n+1 rule
The lower the sum of the values of the first and second quantum numbers, n+1, the lower the energy of the subshell
*Used to rank subshells by increasing energy
*If two subshells possess the same n+1 value, the subshell with the lower n value has a lower energy and will fill the electrons first
Example: For 5d, n=5 and l=2, so n+1=7. For 6s, n=6 and l=0, so n+1=6. Therefore, the 6s subshell has lower energy and will fill first
Hund’s rule
Within a given subshell, orbitals are filled such that there are a maximum number of half-filled orbitals with parallel spins, based on electron repulsion
*Half-filled and fully filled orbitals have lower energies (higher stabilities) than other states
Exceptions to electron configuration
1). Group 6 elements Example: Chromium [Ar]4s1 3d5 2). Group 11 elements Example: Copper [Ar]4s1 3d10 *move an s electron to d subshell so its half-filled or fully filled
Paramagnetic
Magnetic field will cause parallel spins in unpaired electrons and therefore causes an attraction
Diamagnetic
Materials consisting of atoms that have only paired electrons will be slightly repelled
Metal characteristics
Lustrous (shiny) Solid (except mercury) High melting point High densities (except lithium) Malleable Ductility- ability to be drawn into wires Low effective nuclear charge Low electronegativity Large atomic radius Small ionic radius Low ionization energy Low electron affinity Good conductors of heat and electricity
Nonmetal characteristics
Brittle in the solid state Little to no metallic luster High ionization energies High electron affinities High electronegativities Small atomic radii Large ionic radii Poor conductors of heat and electricity
Metalloid characteristics
electronegativities lie between metals and nonmetals
Ionization energies lie between metals and nonmetals
Varied densities, melting points, and boiling points
Good semiconductors
