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Electronic Structure of Atoms

Terms in this set (49)

Electronic Structure
the arrangement of electrons in an atom or molecule
Waves
A disturbance that transfers energy from place to place
Electromagnetic radiation
a form of energy that exhibits wavelike behavior as it travels through space
Speed of Light
3.00 x 10^8 m/s
Wavelength
Horizontal distance between the crests or between the troughs of two adjacent waves
Frequency
the number of complete wavelengths that pass a point in a given time (v)
If wavelengths increase, frequency ........
decreases
Electronic Properties NOT Explained by Waves
1. The emission of light from hot objects (blackbody radiation)
2. The emission of electrons from metal surfaces on which light is shone (the photoelectric effect)
3. Emission of light from electronically excited gas atoms (emission spectra)
Quanta
The bundle of electromagnetic energy that is absorbed or emitted by matter
Photoelectric Effect
The emission of electrons from a metal when light shines on the metal.

E=hv
Planck's constant (h)
6.626 x 10^-34 J x s
Atomic Emission
a set of frequencies of electromagnetic waves given off by atoms of an element; consists of a series of fine lines of individual colors
continuous spectrum
an emission spectrum that consists of a continuum of wavelengths.
Line Spectrum
a spectrum showing only certain discrete wavelengths
Hydrogen Spectrum
-The emission spectrum of hydrogen shows discrete wavelengths
-Indicates that hydrogen has discrete energy levels
Bohr Model
model of the atom in which electrons move rapidly around the nucleus in paths called orbits
Bohr model: ground state
Electrons at the lowest energy state
Bohr model:excited state
Any energy higher
Johannes Rydberg
Developed an equation describing the wavelengths of visible light emitted from a hydrogen atom
1/wavelength=(Rh)(1/n(2/1)-1/n(2/2))
Rh (Rydberg constant)
2.18 x 10-18J
Bohr Model explained
1. Only orbits of certain radii, corresponding to specific energies, are permitted for the electron in a hydrogen atom.
2. An electron in a permitted orbit is in an "allowed" state does not radiate energy, and therefore, does not spiral into the nucleus.
3. Energy is emitted or absorbed by the electron only as the electron changes from one energy state to another. This energy is the emitter of photons absorbed that has a energy. E=hv
Positive Delta E
Means energy absorbed.
A photon is absorbed
Negative Delta E
Means Energy is released.
A photon is emitted in this instance
Limitations of the Bohr Model
-It only works for hydrogen!
-Classical physics would result in an electron falling into the positively charged nucleus. Bohr simply assumed it would not!
-Circular motion is not wave-like in nature.
Important Ideas from the Bohr Model
1. electrons exist only in certain discrete energy levels, described by quantum numbers
2. energy is involved in the transition of an electron from one level to another
Wave Nature of Matter
- brogile
- showed relation between mass and wavelength
- said matter should have wave properties

Wavelength = h/mv
Uncertainty Principle
The more precisely you know the momentum, the less likely you'll have an accurate position
Quantum Mechanics
describes the motions of subatomic particles and atoms as waves
Quantum Mechanics was developed by....
Erwin Schrodinger
Wave Functions
a series of solutions to a wave equation
Electron Density
gives the probability that an electron will be found in a particular region of an atom
Orbitals
regions around the nucleus in which given electron or electron pair is likely to be found
Photon
A particle of electromagnetic radiation with no mass that carries a quantum of energy
Quantum Numbers
Set of numbers used to completely describe an electron;n,
Principal Quantum Number (n)
symbolized by n, indicates the main energy level occupied by the electron
Angular Momentum Quantum Numbers
symbolized by l, indicates the shape of the orbital
Magnetic Quantum Number
symbolized by m, indicates the orientation of an orbital around the nucleus.
Electron shell
An energy level representing the distance of an electron from the nucleus of an atom.
Subshells
Different orbital types within a shell are s,p,d,f
s Orbital
spherical
Radius of the sphere increases with the value of n.
p Orbitals
dumbbell shaped
d Orbitals
most have 4 lobes; and their destiny runs along the axes; can hold a total of 10 electrons in 5 sub-shells
f Orbitals
their shapes are even more complex than s, p, or d orbitals; can hold a total of 14 electrons in 7 sub-shells
Spin Quantum Number
has only two possible values (+1/2, -1/2) which indicate the two fundamental spin states of an electron in an orbital, ms
Pauli Exclusion Principle
An atomic orbital may describe at most two electrons, each with opposite spin direction
Electron Configuration
the arrangement of electrons in an atom
Hund's Rule
electrons occupy orbitals of the same energy in a way that makes the number of electrons with the same spin direction as large as possible
Valence Electrons
Electrons on the outermost energy level of an atom
Transition Metals
elements that form a bridge between elements on the left and right sides of the periodic table
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