# Development of the modern Periodic table

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Development of the modern Periodic table
Chapter 6.1

Periodic  Periodic Law  Periodic Table
Something periodic occurs at regular or at least generally predictable intervals Periodic law - physical and chemical properties of the elements are periodic functions of their atomic numbers Periodic Table of Elements – a table of the elements, arranged by atomic number, that shows the patterns in their properties; based on the periodic law

Element A pure substance made up of one kind of atom that cannot be broken down into simpler substances by physical or chemical means 90 occur naturally on earth 25 were synthesized (made) by scientists

Dmitri Mendeleev In the 1860’s he devised a periodic table where the elements were ordered by their atomic masses He did this by grouping elements together according to their similarities Image taken from:

Mendeleev’s Predictions
Although Mendeleev’s Periodic Table of Elements had missing elements or “gaps”, he was able to predict the characteristics of these missing elements because of Periodic Law.

Henry Moseley In 1914, his work led to a revision of the periodic table by rearranging the elements by their atomic numbers He concluded that the number of protons in an atom is its atomic number Image taken from:

Classes of Elements This zig-zag staircase line separates the metals from the nonmetals. The elements along this line are sometimes called metalloids

What metal is not a solid
Metals Location Found on the left of the zigzag line/staircase on the periodic table (exception  Hydrogen) Chemical Properties Have few electrons in their outer energy level, thus lose electrons easily Physical Properties ductile, good conductors, malleable, shiny, most are room temp. 79 Au 11 Na 22.990 Image taken from: What metal is not a solid @ room temperature?

Atoms with Few Electrons in their Outer Energy Level
Notice: only 1 electron in outer level 11 Na 22.990 Sodium 4 Be 9.012 Beryllium Notice: only 2 electrons in outer level

Non-Metals Location Most found to the right of the zigzag line/staircase on the periodic table Chemical Properties Most have almost full outer energy levels, thus they tend to gain electrons; some have completely full outer level Physical Properties not ductile or malleable, not shiny, poor conductors, most are solid, but some are gas at room temperature 17 Cl 35.453 Image taken from: 16 S 32.066 Image taken from: https://www.dmr.nd.gov/ndgs/rockandmineral/sulfur.asp

Atoms with Full or Almost Full Outer Energy Level
8 O 15.999     Oxygen Notice: 2 electrons in outer level – FULL 2 He 4.003 Helium Notice: 6 electrons in outer level – almost full Notice: 7 electrons in outer level – almost full 9 F 18.998 Fluorine

Metalloids Location Border the zigzag line/staircase on the periodic table Chemical Properties Most atoms have ½ (≈) complete set of electrons in outer level Physical Properties have properties of both metals and non-metals 14 Si 28.086 Image taken from: 5 B 10.811 Image taken from:

Atoms with ½ (≈) Complete Outer Energy Level
Notice: only 4 electrons in outer level                     5 B 10.811 Boron Notice: only 3 electrons in outer level 14 Si 28.086 Silicon

Using the Periodic Table
Atomic Number (Number of protons) Electron Configuration (Written in order of orbitals from top to bottom: top is innermost and bottom is outermost [valence]) Element Symbol (Written with a capital letter or a capital followed by a lower case if two letters ) Element Name Atomic Mass (Rounded to a whole number, equals the number of protons and neutrons)

Using the Periodic Table
Letters are color coded based on the natural physical state of the element The boxes of each element are color coded based on the group (or subgroup) to which the element belongs

Today – 11/10/14 Complete Ch. 6 Vocabulary Page 197 (20 words)
Due by end of class – NO EXCUSES Begin color-coding Periodic Table 1 side: metals, nonmetals & metalloids Names of groups 2nd side: periodic trends Atomic radius Ionic radius Ionization energy Electronegativity