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Periodic Table. Patterns in Element Properties. Some elements exhibit similar chemical and physical properties. For example, lithium (Li), sodium (Na), and Potassium (K) can all combine in a 1:1 ratio easily with Chlorine. Elements With Similar Properties.

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Periodic Table

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Periodic Table


Patterns in Element Properties

  • Some elements exhibit similar chemical and physical properties. For example, lithium (Li), sodium (Na), and Potassium (K) can all combine in a 1:1 ratio easily with Chlorine.


Elements With Similar Properties

  • The elements chlorine, bromine, and iodine look very different from each other. But each forms a similar-looking while solid when it reacts with sodium.


John Newlands Noticed a Periodic Pattern

  • In 1865, an English chemist, John Newlands, arranged the known elements according to their properties and in order of increasing atomic mass.

  • He noticed that all of the elements in a given row had similar properties, and they repeated every 8 elements (he called this the law of octaves).


Newlands’ Table

  • In Newland’s time, determining atomic

    weights was based on comparing other elements to the lightest element

    (hydrogen). Some of the elements were

    given inaccurate values. .

  • Newland was ridiculed by other chemists who felt the table he created was not reliable. He could not get his papers published and returned as chief chemist in a sugar factory and later opened a chemical business with his brother.


Dmitri Mendeleev Invented the First Periodic Table

  • In 1869, a Russian chemist, Dmitri Mendeleev produced the first orderly arrangement (periodic table) of all 63 elements known at the time.


Mendeleev—the Father ofthe Periodic Table

  • Mendeleev (1834-1907) rose from very poor beginnings to a position of a renowned Russian chemist in the 19th century. He wrote down information on each element on cards. He ranked the elements from lightest to heaviest.

  • Mendeleev also put the elements into a table according to their properties. He started a new row each time he noticed that the chemical properties of the elements repeated.


Mendeleev Correctly Predicted the Gaps

  • Mendeleev’s Table contains gaps that elements with particular properties should fill.

  • He correctly predicted the

    properties of the missing

    elements. He even gave them

    provisional names. These

    elements were eventually

    discovered.


Henry Moseley

  • A young English chemist, Henry Moseley, discovered that the elements should be organized according to their atomic numbers, not their atomic weights as was done before.

  • When Moseley studied the lines in

    the X-ray spectra of 38 different

    elements, he found that the

    wavelength of the lines decreased

    in a regular manner as atomic

    number increased.


Henry Moseley

  • Henry Moseley lost his life in 1915

    during World War I at the Gallipoli

    battle in Turkey at the age of 27 and

    is buried there. His death has been called

    one of the greatest

    tragedies of WWI

    because he was such

    a brilliant chemist.


The Periodic Law

  • The Periodic Law states that when the elements are arranged according to their atomic numbers, elements

    with similar properties

    appear at regular intervals.


Organization of the Periodic Table

  • Elements in each column of the table have the same number of electrons in their outer energy level.

  • These electrons are called valence electrons.


Valence Electrons

  • The outer energy level electrons in an atom are the ones that participate in chemical reactions with other atoms.

  • Elements with the same number of valence electrons react in similar ways.


Groups

  • A vertical column on the periodic table is called a group. (These are also called families.) These exhibit similar properties.


Relationship between Groups and Electron Configuration:

  • The group an element belongs to is determined by the last notation in its’ electron configuration.

  • For example, all elements that end in s1 have the same properties and are in the same group.


Periods

  • A horizontal row on the periodic table is called a period. Elements in the same period have the same number of occupied energy levels.


Blocks of Elements

  • The Periodic Table is organized into blocks—each corresponding to the sublevels. (S, P, D, and F)


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