Structure of Atoms-Chapter 4
What are the three fundamental particles
electrons, protons, and neutrons
Charge of a proton, electron and nucleus of an atom?
proton- equal in magnitude, but opposite in charge to an electron.
Electron- Negatively Charged
Atomic Nucleus- Positively charged
introduced the term electron "as the fundamental unit quantity of electricity"
-chemist and inventor
-Suggested that the elements of a chemical compound are held together by electrical forces.
-determined the quantitative relationship between the amount of electricity used in electrolysis, and the amount of chemical reaction that occurs.
Cathode Ray Tubes
Two electrodes are sealed in a glass tube containing gas at a very low pressure. When a high voltage is applied, current flows and rays are given off by the cathode (negative electrode). These rays travel in straight lines toward the anode (Positive Electrode) and cause the walls opposite of the cathode to glow. An object placed in the path of the cathode ray casts a shadow on a zinc sulfide fluorescent screen placed near the anode. The shadow shows that the rays travel from the negatively charged cathode toward the positively charged anode. This tells us that the rays MUST be negatively charged.
-Determined the ratio of the charge of the electrons to its mass.
-Accredited with the discovery of electrons (the 1st fundamental particle)
-Invented the mass spectrometer
-Credited with finding the 1st evidence of isotopes in a stable (non-radioactive) element
-Plum pudding model of the atom
e/m=1.75882x10^8 coulomb (C)/g
ratio of charge of an electron to its mass
-Determined the Charge of the electron
(4 properties of cathode rays)
-Are negative electrode rays
-Travel in a straight line
-have a negative electric charge
-He was an early investigator of discharge tubes, the discoverer of anode rays, and is sometimes credited with the discovery of the proton.
-a subatomic particle with one unit of positive charge
-known as the "father of nuclear physics"
-discovered and named the proton
-rutherford "scattering experiment"
-accredited with the discovery of the nucleus of an atom
-Discovered 3 types of radioactivity- alpha particles, beta particles, and gamma rays
-accredited with the discovery that every element differs form the preceding element by having one or more (+) charge in its nucleus
The number of protons in the nucleus of an atom
-accredited with the discovery of the neutron
any of two or more forms of a chemical element, that have the same number of protons in the nucleus (atomic number), but have different numbers of neutrons in the nucleus (atomic Weights)
Mass Number (Atomic Number)
# of protons + # of neutrons
a= Mass Number (protons+neutrons)
z=Atomic Number (protons)-also equal to the number of electrons in neutral atom.
VC- Groups or families
HR- periods (all have properties that change progressively across the table)
The distance between two adjacent identical points of the wave
The number of wave crests passing a given point per unit time
The relationship between the wavelength and the frequency of electromagnetic radiation
The photo Electric Effect
(The Hertz Effect)
the observation that many metals emit electrons when light shines upon them. Electrons emitted in this manner may be called photoelectrons.
Wave nature of the electron
-h= plancks constant
4 types of quantum numbers
1. Principal quantum number=m (Main Shell)
2. angular momentum quantum number=l (sub shell)
3. Magnetic quantum number= ml (a specific orbital within a sub shell)
4. Spin Quantum number= ms ( the spin of an electron and the magnetic field produced by its spin)
How many electrons can ay atom hold in each orbital at a time?
What are shells Called?
Electron Energy Levels
Spin quantum number as two possible values
+1/2 and -1/2
Spin paired or simply paired electrons
two electrons in the same orbital, with opposite charges
Pauli Exclusion Principle
no TWO electrons in an atom may have identical sets of four quantum numbers
an electron in an orbital by itself
Regio of space in which finding an electron is high
Electrons occupy all the orbitals of a given sub shell singly before pairing begins. These unpaired electrons have parallel spins
a guide for predicting the order in which electrons fill sub shells and shells in atoms
2+ orbitals that have the same energy
the lowest energy state or most stable state of an atom, molecule, or ion.
Spontaneous Decomposition of an atom
Noble (rare) Gases
Elements of Group 8A in the periodic Table
A "packet" of light or electromagnetic radiation; also called quantum light
a mathematical method of treating particles on the basis of quantum theory, which assumes that energy (of small particles) is not infinitely divisible.
any of the number of lines corresponding to definite wavelengths in an atomic emission or absorption spectrum; these lines represent the difference between two energy levels
Display of component wavelengths of electromagnetic radiation
Black body Radiation
is the type of electromagnetic radiation within or surrounding a body in thermodynamic equilibrium with its environment, or emitted by a black body (an opaque and non-reflective body) held at constant, uniform temperature.
Planck's law describes the electromagnetic radiation emitted by a black body in thermal equilibrium at a definite temperature.
The 3 postulates of the BOHR model
1. in an atom, electrons revolve around a nucleus in orbits, or shells
2.Each shell or orbits corresponds to a certain energy level, thus they are called Electron energy levels
3.Each orbit or Electron energy level, has quantum numbers that correspond with each
Bohr's Principle of Complementarity
It holds that objects have complementary properties which cannot be measured accurately at the same time.
Heisenberg Uncertainty Principle
more precisely the position of some particle is determined, the less precisely its momentum can be known, and vice versa.
discovered that electrodes illuminated with ultraviolet light create electric sparks more easily.
explained experimental data from the photoelectric effect as being the result of light energy being carried in discrete quantized packets (called Photons)
arrived at the understanding that cathode rays were streams of negatively charged energetic particles.