Atomic Structure and Periodicity
Dive into the fascinating world of atomic structure and the duality of electrons. This exploration reveals how electrons exhibit both particle and wave characteristics, as discussed by groundbreaking physicists such as JJ Thomson and Louis de Broglie. Learn about the principles of wave-particle duality, electron transitions, and energy levels, along with the significance of spectroscopic analysis in understanding atomic behavior. Key concepts like energy transitions, isoelectronic substances, and orbital shapes are clarified for a comprehensive understanding of atomic theory.
Atomic Structure and Periodicity
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Presentation Transcript
Confused??? You’ve Got Company! “No familiar conceptions can be woven around the electron; something unknown is doing we don’t know what.” Physicist Sir Arthur Eddington The Nature of the Physical World 1934
The Wave-like Electron The electron propagates through space as an energy wave. To understand the atom, one must understand the behavior of electromagnetic waves. Louis deBroglie
Wave-Particle Duality JJ Thomson won the Nobel prize for describing the electron as a particle. His son, George Thomson won the Nobel prize for describing the wave-like nature of the electron. The electron is a particle! The electron is an energy wave!
Electromagnetic radiation propagates through space as a wave moving at the speed of light. The Wave Like Electron c = C = speed of light, a constant (3.00 x 108 m/s) = frequency, in units of hertz (hz, sec-1) = wavelength, in meters
The Wave Like Electron Types of electromagnetic radiation:
Long Wavelength = Low Frequency = Low ENERGY Wavelength Table Short Wavelength = High Frequency = High ENERGY
Spectroscopic analysis of the visible spectrum… …produces all of the colors in a continuous spectrum
Spectroscopic analysis of the hydrogen spectrum… …produces a “bright line” spectrum
Electron transitionsinvolve jumps of definite amounts ofenergy. This produces bands of light with definite wavelengths.
Niels Bohr Proposed that the electron in a hydrogen atom moves around the nucleus only in certainallowed circular orbits.
The energy (E ) of electromagnetic radiation is directly proportional to the frequency () of the radiation. E = h E = Energy, in units of Joules (kg·m2/s2) h = Planck’s constant (6.626 x 10-34 J·s) = frequency, in units of hertz (hz, sec-1)
Relating Frequency, Wavelength and Energy Common re-arrangements:
Electron Energy in Hydrogen n = energy level ***Equation works only for atoms or ions with 1 electron (H, He+, Li2+, etc).
Calculating Energy Change, E, for Electron Transitions Energy must be absorbed from a photon (+E) to move an electron away from the nucleus Energy (a photon) must be given off (-E) when an electron moves toward the nucleus
Electron configuration of the elements of the first three series
Irregular confirmations of Cr and Cu Chromium steals a 4s electron to half fillits 3d sublevel Copper steals a 4s electron to FILL its 3d sublevel
ISOELECTRONIC SUBSTANCES and EXCITED STATES • Substances with the same number of electrons are isoelectronic ions. • Isoelectronic ions (or molecules) ions (or molecules) with the same number of valence electrons. • Isoelectronic substances: P3, S2, Cl, Ar, K+, Ca2+. • The electron configation of an element in an excited state will have an electron in a high-energy state E.g. [Ar]4s13d94p1 is an excited-state electron configuration for Cu.
Sizes of sorbitals Orbitals of the same shape (s, for instance) grow larger as n increases… Nodes are regions of low probability within an orbital.
The s orbital has a spherical shape centered around the origin of the three axes in space. s orbital shape
P orbital shape There are three dumbbell-shaped porbitals in each energy level above n = 1, each assigned to its own axis (x, y and z) in space.
Things get a bit more complicated with the five d orbitals that are found in the d sublevels beginning with n = 3. To remember the shapes, think of: “double dumbells” …and a “dumbell with a donut”!
