Modern Atomic Theory
Modern Atomic Theory and The Periodic Table
A Brief History
Atomic theory has changed over the past 2000 years:
–Early Greek Ideas:
–Dalton’s Model:
–Thomson’s Model:
–Rutherford’s Model:
Electromagnetic Radiation
Basic wave characteristics:
–Wavelength ( )
–Frequency ( )
–Speed ( )
Light is a form of ____________________________.
Light can also be considered to be composed of energy packets called
_______________, which behave like _________________.
Diagram:
The Bohr Atom
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Modern Atomic Theory
Diagrams:
German physicist Max Planck (1858 – 1947) observed the line spectrum of
hydrogen and theorized that emitted energy is not a continuous stream but
occurring in small discrete units called a _____________________.
Danish physicist Niels Bohr (1885 – 1962) applied this concept to the single
electron “orbiting” the nucleus in the hydrogen atom.
The study of atomic spectra led Bohr to propose that:
–Electrons are found in _____________________________ in an atom.
–Spectral lines result from the radiation of quanta of energy when the
electron __________________________________________________.
The lowest energy level is called _________________________.
Any level above ground state is called an _____________________________.
The chemical properties of an element and its position on the periodic table
depend on ________________________.
Bohr’s ______________________________ for hydrogen does not work for
any other element.
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Modern Atomic Theory
Quantum Theory
In 1924, Louis de Broglie suggested that all matter has ___________________.
–Large objects have wave properties _____________________________.
–Very small particles, _____________, have observable wave properties.
In 1926, Erwin Schrodinger created a mathematical model that described the
wave behavior of the electron.
This model can determine the _______________________of finding an electron
in a certain region around the nucleus of the atom.
This branch of physics is called ___________________________.
Electrons are found in ________________-, a region in space around the
nucleus where there is a high probability of finding an electron.
–When this mathematical orbital is visualized, the orbital looks like a
cloud (hence, the electron cloud).
Modern atomic theory predicts the following:
Electrons are found in discrete ___________________________ (n = 1, 2, 3…).
Energy levels contain ____________________ (s, p, d, f).
Sublevels contain __________________ (s = 1, p = 3, d = 5, f = 7).
Each orbital holds ____________________ (s = 2e-, p = 6e-, d = 10e-, f = 14 e-)
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Modern Atomic Theory
Electrons fill lowest energy sublevels first:
1s
2s
3s
4s
5s
6s
7s
2p
3p
4p
5p
6p
7p
3d
4d
5d
6d
4f
5f
Periodic Trends
Classification of Elements
The Periodic Table Revisited.
–Russian chemist __________________________ introduced the most
successful arrangement of the elements to date in 1871.
–Vertical rows were arranged by ______________________________.
–Horizontal rows were arranged by
____________________________________________.
_____________________________ arranged the first modern periodic table.
–This periodic table now contains information regarding the chemical
symbol, atomic number, average atomic mass, physical state of each
element, group’s numbers, electron configurations, as well as many other
useful characteristics.
–Recently accepted names for elements 104-109 have been added.
–This periodic table is arranged mainly based on increasing
_____________________________.
The modern periodic table is extremely useful in understanding and predicting
properties of elements.
Elements and Electron Configuration
– _________________ play the most significant role in determining the
physical and chemical properties of an element.
–A relationship exists between the ____________________________ of
the elements and their ____________________ in the periodic table.
Categories of elements.
–The noble gases.
•These are elements in which the outermost s and p sublevels are
_______________________.
•These elements are also called the ________________ because
they do not participate in many chemical reactions.
•Electron configurations:
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Modern Atomic Theory
Categories of elements.
–The representative elements.
•In these elements, the outermost s or p sublevel is only partially
filled.
•These are the ______________ elements.
•Electron configurations of the alkali metals:
•Electron configurations of the alkaline earth metals:
•Electron configurations of the halogens:
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Modern Atomic Theory
•The transition elements.
–These are the metallic elements in which the outermost s
sublevel and nearby d sublevel contain electrons.
–These are the ________________ elements.
•The inner transition elements.
–These are the metallic elements in which the outermost s
sublevel and nearby f sublevel generally contain electrons.
•Similarities within groups of elements.
–Alkali metals:
–Alkaline earth metals:
–Halogens:
–Noble gases:
• Summary statement:
Periodic Trends
•Trends in Atomic Size.
–The atomic radius is:
–The atomic
radius of an element indicates its relative size.
•Group Trends:
•Periodic Trends:
•Trends in Ionization Energy.
–Ionization energy is:
•Group Trends:
•Periodic Trends:
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Modern Atomic Theory
•Trend in Ionic Size.
•Group Trends:
–Positive ions (cations) are always
_____________________________________________________.
–Negative ions (anions) are always
_____________________________________________________.
–Within a group:
•Period Trends:
•Trend in Electronegativity.
•Electronegativity is
•Group Trend:
•Periodic Trends:
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Modern Atomic Theory
•Range: 0.7 for Cesium to 4.0 for Fluorine.
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