1 / 13

THE PERIODIC TABLE

THE PERIODIC TABLE. Classification of Elements. Early Attempts at Classification. Johann Dobereiner- A German chemist, in 1817 found several groups of three elements with similar properties that he called Triads. Early Attempts at Classification.

kjulie
Download Presentation

THE PERIODIC TABLE

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. THE PERIODIC TABLE Classification of Elements

  2. Early Attempts at Classification • Johann Dobereiner-A German chemist, in 1817 found several groups of three elements with similar properties that he called Triads.

  3. Early Attempts at Classification • John Newlands- An English chemist in 1863, suggested another classification. • He arranged the elements in order of their increasing atomic masses. • He proposed the Law of Octaves to explain the repetition of similar properties that occurred with every eighth element when elements were arranged in order of increasing atomic mass.

  4. Early Attempts at Classification • Dmitri Mendeleev- A Russian chemist, just six years after Newland’s proposal, suggested that the properties of the elements were a function of their atomic masses. This was the First Periodic Law. • Mendeleev developed the first periodic table arranged so that elements with similar properties were in the same vertical column. He correctly predicted properties and masses of unknown elements.

  5. Early Attempts at Classification • Henry Moseley- His x-ray experiments showed that the nucleus of each element has an integral positive charge, the Atomic Number. • As a result of Moseley’s work the periodic law was revised.

  6. THE PERIODIC LAW • The modern statement of the periodic law is the properties of the elements are a periodic function of their atomic numbers.

  7. The Modern Periodic Table • Elements with similar configurations are listed in the same column or group. • Elements are listed in the column in order of their increasing principal quantum number. • The numbers on the left side of the table are the values for n, and correspond to the main energy level.

  8. The Modern Periodic Table • The first 2 columns (1-2) consist of elements that have electrons filling the s-sublevel. • The elements in the last six columns on the right (13-18) are elements that have electrons filling the P sublevel.

  9. The Modern Periodic Table • The 10 columns in the center of the chart (3-12) contain the transition elements whose electrons are filling an inner d sublevel having a quantum number of (n-1). • The two horizontal rows at the bottom of the table represent the elements with a quantum number of (n-2) whose electrons are filling the inner f sublevel.

  10. The Modern Periodic Table • A Group or Family is a vertical column on the periodic table. • A Period or series is a horizontal row on the periodic table. • The table is broken down into metals, nonmetals, and metalloids. • The metals and nonmetals are separated by a heavy black stair- step line.

  11. Metals • have luster, they are shiny • conduct heat and electricity. • usually bend without breaking, they are malleable, ductile and tenacious. • reflect light

  12. Nonmetals • brittle as solids • dull • poor conductors • good insulators • usually gases at room temperature.

  13. Metalloids • Elements with some physical and chemical properties of metals and other properties of nonmetals.

More Related