The Periodic Table Ms. Pollock Physical Science

Organizing the Elements Dmitri Mendeleev’s periodic table published in 1869 in RussiaDmitri Mendeleev’s periodic table published in 1869 in Russia Born in Siberia in 1834Born in Siberia in 1834 Chemistry professor at University of St. PetersburgChemistry professor at University of St. Petersburg Wrote textbook for students; led to development of periodic tableWrote textbook for students; led to development of periodic table Extremely accurate periodic table for timeExtremely accurate periodic table for time

Dmitri Ivanovich Mendeleev ory/curie/periodic.htm

Mendeleev’s Table Just over 60 elements identified at the timeJust over 60 elements identified at the time Organized by atomic weights (masses) and found that the properties of elements repeated periodicallyOrganized by atomic weights (masses) and found that the properties of elements repeated periodically Not all elements known, so some spaces left blankNot all elements known, so some spaces left blank Accurately predicted properties of elements not yet discoveredAccurately predicted properties of elements not yet discovered

Mendeleev’s Table

Improving the Periodic Table Henry Moseley, 1913Henry Moseley, 1913 Found that some elements did not line up perfectly in Mendeleev’s tableFound that some elements did not line up perfectly in Mendeleev’s table Re-ordered elements by atomic number, rather than atomic massRe-ordered elements by atomic number, rather than atomic mass British; studied with Ernest RutherfordBritish; studied with Ernest Rutherford Killed in World War IKilled in World War I

Henry Moseley o.nz/henry_moseley.htm

The Atom and the Periodic Table Elements sorted according to propertiesElements sorted according to properties Groups – vertical columns; similar propertiesGroups – vertical columns; similar properties –Same group = electrons in same energy level –Electrons in same energy level = similar chemical properties and behavior Periods – horizontal rowsPeriods – horizontal rows –Each row a new energy level –Row 1 = 1 energy level –Row 7 = 7 energy levels

The Atom and the Periodic Table

Electron Dot Diagrams Elements in same group have the same number of electrons in their outer energy levels.Elements in same group have the same number of electrons in their outer energy levels. The outer energy level can be drawn using an electron dot diagram.The outer energy level can be drawn using an electron dot diagram. The symbol of the element and a series of dots are used to represent electrons in the outer energy levels.The symbol of the element and a series of dots are used to represent electrons in the outer energy levels. Developed by American chemist G. N. LewisDeveloped by American chemist G. N. Lewis

Electron Dot Diagrams Write the symbol first.Write the symbol first. Then, place one electron at each side of the symbol.Then, place one electron at each side of the symbol. Finally, pair electrons until all valence (outer shell) electrons are accounted for.Finally, pair electrons until all valence (outer shell) electrons are accounted for.

Electron Dot Diagrams Cl Group 17: Valence electrons cannot exceed 8 (octet rule), so take the group number (17) and subtract – 10 = 7 valence electrons

Electron Dot Diagrams Cl

Electron Dot Diagrams Cl

Electron Dot Diagrams Cl

Electron Dot Diagrams Cl

Electron Dot Diagrams Cl

Electron Dot Diagrams Cl

Electron Dot Diagrams Cl

Regions on the Periodic Table Several areas on periodic table with specific namesSeveral areas on periodic table with specific names Left = metals (mostly solids)Left = metals (mostly solids) Right = nonmetals (mostly gases)Right = nonmetals (mostly gases) Zig-zag line = metalloidsZig-zag line = metalloids Extra rows = Lanthanides and ActinidesExtra rows = Lanthanides and Actinides

Periodic Table Regions (Metals)

Periodic Table Regions (Nonmetals)

Periodic Table Regions (Metalloids) katie-maggie-mettaloids-g.wikispaces.com

Elements in the Universe Modern technology making elements in other parts of universe easy to identifyModern technology making elements in other parts of universe easy to identify Hydrogen and helium thought building blocks of other elementsHydrogen and helium thought building blocks of other elements Many elements found only in stars or as a result of the decay of other elementsMany elements found only in stars or as a result of the decay of other elements