Chapter 7-Exam 3 Flashcards
The uncertainty principle
Uncertainty in the precision we can simultaneously specify the position and linear momentum of a particle
Heisenberg
Showed that the more precisely the linear momentum is know, the less precisely the position is known
Linear momentum formula
p=mu
m=mass
u=speed
n, l and ml meanings
n=principle quantum number
l=angular momentum quantum number
ml=magnetic quantum number
Orbitsl
A one-electron wave function for a given set of m, l and ml
Shell
A collection of orbitals with the same value for n
Subshell
A set of orbitals with the same value for l
Principle quantum number
(b) defines energy levels and shells, takes into account the radial dependence of the electronic motion
Angular momentum quantum number
(l) defines subshells, related to orbital shape
Magnetic quantum number
(ml) related to the orientation of an orbital around the nucleus
Electron spin
(ms)A property of an electron that makes it interact with an external magnetic field. has values of + or - 1/2
Pauli exclusion principle
No two electrons in an atom can have the same set of 4 quantum numbers. An orbital can hold a maximum of 2 electrons and they must have opposite spins
Born postulate
Wave function is not an actual wave, it is an abstract mathematical entity called probability amplitude. It can be used to find observables such as energy. Wave function squared the probability density for finding an electron at a given point in space.
Radial distribution profile
A graphical representation of finding an electron in a thin spherical layer near the nucleus of an atom
s Orbitals
Spherically shaped with highest electron density near nucleus, electron exhibits maxima at finite distance from nucleus
Nodes
Where electron density=0, number of
nodes in H atom=n-1. Nodes are divided into radial(concentric spheres) and angular cones or planes. In an orbital, there are n-l-1 radial nodes and l angular nodes
degeneracy
An energy level is degenerate if it corresponds to more than one state/orbital.
Degree of degeneracy
The number of different states corresponding to the same energy level
Aufbau principle
Method of building electron configurations by adding one electron at a time as atomic number increases
What are characteristics of electrons when adding them to an orbital?
They usually go in the lowest orbital possible, there are a maximum of 2 electrons per orbital
Hund’s rule
The lowest energy configuration maximizes the number of unpaired electron
What does the energy of an H atom depend on?
Principle quantum number (n)
isoelectronic
Atoms/ions having identical electron configurations
how are transition metal cations formed?
they lose electrons from the orbitals with the highest n value first
atomic radius
half the distance between identical nuclear centers in a molecule
Metallic radius
half the distance between nuclear centers in the solid metal
Ionic radius
derived from the distance between nuclear centers in solid ionic compound
Trends for atomic radii size and reasoning for them
- Increased going down a column: number if valence electrons increases with atomic number, more electron-electron repulsion
- Decreases going across a row: increasing attraction for electrons
Effective nuclear charge trends
S electrons experience the greatest Zeff followed by p, d, and f electrons. For S and P blocks, Zeff increases across a period and decreases down a group
Ionic radii trends
Cations: cations of main group elements are much smaller than their parent atom, remaining electrostatic attraction is greater for remaining electrons
Anions: Much larger than parent atom, electron-electron repulsion is increased
Ionization energy
The minimum energy required to remove an electron from the ground state of the isolated gaseous atom or ion
Last ionization energy of element
IEz=-E1
Ionization potential
electronvolts(eV) that ionization energies are given in, defined as the kinetic energy that an electron acquires when accelerated through a potential difference of 1 volt
Effective nuclear charge
The nuclear charge that an electron experiences from attraction to the nucleus and repulsion from other electrons, Zeff=Z-S, can not be calculated with complete accuracy
Electron affinity definitions
- The energy change that occurs when an electron is added to a gaseous atom, can be endothermic or exothermic
- The energy change associated with adding an electron to an element
Wavelength formula using speed
wavelength=h/mu
Equation associated with electron affinity
Electron added to neutral atom, resulting in anion with charge of -1
Equation associated with ionization energy
Cation+electron on one side, ion with appropriate charge on the other side
Electron affinity reaction
Exothermic: X(g)+e-▶️X-
Endothermic: X-▶️X(g)+e-
Ionization energy reaction
X(g)▶️X+(g)+e-(endothermic)
which molecular geometry is nonpolar?
Square planar
Steric numbers and bond angles
2=180 3=120 4=109.5 5=120/90 6=90
