Structure of Atom and Quantum Mechanics

Vocabulary flashcards based on lecture notes about the structure of atoms, subatomic particles, and quantum mechanics.

Electrons, Protons, and Neutrons

The three main subatomic particles that form an atom.

Michael Faraday's Cathode Ray Discharge Tube Experiment

An experiment using a partially evacuated glass tube with high voltage applied across electrodes to discover electrons.

Cathode Rays

Particles that move from the cathode (-ve) to the anode (+ve) in a cathode ray discharge tube.

Phosphorescent or Fluorescent Materials

Materials, like zinc sulphide, used to observe cathode rays.

Charge to Mass Ratio of Electrons

The ratio of charge (e) to the mass of an electron (me), measured by J.J. Thomson.

J.J. Thomson's Apparatus

Apparatus uses electric and magnetic fields perpendicular to each other to determine the charge to mass ratio of electrons.

Falling Rate

The rate at which oil droplets fall, used to ascertain their mass in Millikan's experiment.

X-ray Beam

Used to ionize the air in Millikan’s Oil-Drop Experiment

Canal Rays

Particles carrying a positive charge discovered in a modified cathode ray tube.

Proton

The smallest and lightest positive ion, obtained from hydrogen.

Neutrons

Electrically neutral particles discovered by Chadwick.

Plum-Pudding Model

Atomic model proposed by Thomson, comparing the atom to plum pudding or a watermelon.

E. Goldstein

Discovered positively charged particles (protons) in 1886 using a gas discharge tube.

J.J Thomson and his colleagues

Conducted experiment with discharge tube apparatus to discover cathode rays

Cathode Rays Experiment

Conducted experiment using discharge tube apparatus

Sir Joseph John Thomson

British physicist known for the discovery of electrons and the plum-pudding model.

Eugen Goldstein

German physicist known for the discovery of canal rays, leading to the discovery of protons.

Canal Rays Experiment

Experiment conducted by Goldstein which is similar to J.J Thomson’s but with some modifications

Protons

positively charged particles of hydrogen

Rutherford

He bombarded the gold foil with alpha particles in experiment with gold foil

Gold Foil

Used for its high malleability in Rutherford’s experiment.

Ernest Rutherford

British chemist and physicist known as the father of nuclear physics.

Electromagnetic Radiations

Radiation associated with electric and magnetic fields.

Frequency (ν)

Number of waves that pass a given point in one second.

Wave Number

Number of wavelengths per unit length, reciprocal of wavelength.

Black Body

An ideal body which absorbs and emits all radiation

Photoelectric Effect

The phenomenon where electrons are ejected from the surface of a metal when exposed to light.

Threshold Frequency

Minimum frequency of light below which photoelectric effect is not observed.

Quanta

Radiant energy emitted or absorbed discontinuously in the form of small packets of energy.

Planck’s Constant (h)

Constant that relates the energy of a photon to its frequency, approximately 6.626 × 10−34 Js.

Work Function (hν0)

The minimum energy required to remove an electron from a metal surface.

Spectrum

The spreading of white light into colored bands.

Emission Spectrum

Spectrum of radiation emitted by a substance that has absorbed energy.

Absorption Spectrum

Photographic negative of an emission spectrum.

Spectroscopy

Study of emission or absorption spectra.

Line Spectra or Atomic Spectra

Spectra with discrete frequencies and dark spaces, emitted by atoms in the gas phase.

Balmer Series

Series of lines in the hydrogen spectrum, appearing in the visible region.

Rydberg Constant for Hydrogen (RH)

Constant used in the formula describing all series of lines in the hydrogen spectrum, approximately 109,677 cm−1.

Lyman Series

Series of lines in the hydrogen spectrum corresponding to n1=1.

Balmer Series

Series of lines in the hydrogen spectrum corresponding to n1=2.

Paschen Series

Series of lines in the hydrogen spectrum corresponding to n1=3.

Brackett Series

Series of lines in the hydrogen spectrum corresponding to n1=4.

Pfund Series

Series of lines in the hydrogen spectrum corresponding to n1=5.

Orbits

Paths where electrons move around the nucleus in a circular path of fixed radius and energy

Bohr’s frequency rule

Energy is absorbed when electron jumps from lower orbit to a higher orbit and is emitted when electron jumps from higher orbit to a lower orbit.

principal quantum numbers

The stationary states of electron are numbered as n = 1, 2, 3 …

ionized hydrogen atom

Hydrogen atom which is free from the influence of nucleus

Bohr’s theory

Model to the ions, which are similar to hydrogen atom (containing only one electron)

Stark effect

Splitting of spectral lines in electric field

Zeeman effect

Splitting of spectral lines in magnetic field.

De Broglie gave

The relationship between wavelength (λ) and momentum (p) of a material particle.

Heisenberg’s Uncertainty Principle

Impossible to determine simultaneously the exact position and the exact momentum of an electron (microscopic particle) with absolute accuracy and certainty

Quantum mechanics

Branch of science developed to accounts into the dual nature (particle and wave) of matter

Wave functions

Solutions of Schrodinger equation

orbital

Each permitted solution corresponds to a definite energy state

atomic orbital

Wave function for an electron in an atom

Principal quantum number (n)

Determines the size and energy of the orbital

Azimuthal quantum number (l)

Defines the three-dimensional shape of an orbital

magnetic orbital quantum number (ml)

Gives information about the spatial orientation of the orbital

electron spin quantum number (ms).

Designates the orientation of the spin of an electron

Boundary Surface Diagrams

Give a representation of the shape of the orbitals

Effective nuclear charge (Zeff e)

Net positive charge experienced by the electrons from the nucleus

Aufbau Principle

Orbitals are filled in the increasing order of their energy

Pauli Exclusion Principle

No two electrons in an atom can have the same set of all the four quantum numbers

Hund’s Rule of Maximum Multiplicity

Pairing of electrons in the orbitals belonging to the same sub-shell (p, d, or f) does not take place until each orbital belonging to that sub-shell has got one electron each (i.e., singly occupied)

degenerate orbitals

Orbitals of equal energy (i.e., same sub-shell) are called