Notes on the Periodic Table

Antoine Lavoisier  1790’s made a list of all the known elements; there were 23  By the 1870’s, there were 70 known elements  A system of organization was needed

Dimitri Medeleev tbn1.gstatic.com/images?q=t bn:ANd9GcTzeKUuTTXAuY9m tgzBOeJXppe- olCc5lOuLAVqtgZBIZOuNKQA Was given credit for the first periodic table even though John Newland also developed an organizational system. Based on increasing atomic mass and similar chemical properties

Dimitri Medeleev tbn0.gstatic.com/images?q=tbn:ANd9GcTdPYDxtXWpDpW W-T2xbDAILg8GYvV0SdyF3CIM3n7UMAT5370t9g Predicted the existence of unknown elements Some elements were out of order

Henry Mosely Measured the frequency of the X-rays given off by different elements. Each element gave a different frequency Frequency was mathematically related to the position of the element in the Periodic Table He could actually measure atomic number

Re- designed the periodic table to show an increase in atomic number. Periodic Table now follows the periodic law. Henry Mosely qdefault.jpg

Parts of the Periodic Table Metals Non-Metals tbn2.gstatic.com/images?q=tbn:ANd9GcQQYeaG_K1m_iAi94IxSj_3tKHiOyhvEw5hDquCJ6ui0tu1DWMsfA

Metals content/uploads/2012/08/malleable.pn g tbn3.gstatic.com/images?q=tbn:ANd9Gc RCdH6G0hOn5k4q1Tq3XWuJ_SMrhX9w MIk_4jm7j7LzMaM1NW_T_CJ9iq_O s/Good%20conductor.gif Ductile Good conductors of heat and electricity

Metals Are likely to lose electrons, forming positive ions called cations. c07a3adadcf27.jpg

Alkali Metals Most reactive group of metal elements All contain 1 valence electron Lithium Metal Click on metal to watch a cool you tube video!

Alkaline Earth Metals Also a very reactive metal group. Not as reactive as Alkali metals.

Metalloids Separate the metals from the non-metals Found along the staircase Have properties of both metals and non-metals Are 7 of them mage/3-period-table-metals.gif Used in computer chips Used in solar cells

Non- Metals Are brittle, poor conductors of heat and electricity and many are gases at room temperature. Are likely to gain electrons to form negatively charged ions or anions large.jpg S 2-

Halogens Most reactive group of non-metals Found in Group 17 or VII A Fluorine is the queen. Chlorine, Bromine and Iodine at room temperature. Fluorine could not be included due to its high reactivity.

Noble or Inert Gases Least reactive/ most stable group on the periodic table Each element has 8 valence electrons with the exception of He, which only has 2 Click on picture to watch a cool video!

Transition and Inner Transition Metals d sublevels f sublevels

Period vs. Group Period Horizontal rows on table Have principal quantum numbers of 1-7 Elements in a period have different properties because they all have different numbers of valence electrons. All valence electrons occupy the same principal energy level. Group Also known as a family Have similar chemical properties because they all have the same number of valence electrons. Valence electrons occupy different principal energy levels.

Numbering the Periodic Table Old Way A groups and B groups – B groups were the transition elements – A groups were the rest Used Roman Numerals to indicate the number of valence electrons for the A groups Valence electrons are important for bonding /chemical properties All elements want 8 valence electrons New Way Numbering the periodic table groups from 1-18 Makes all periodic tables uniform Slightly more difficult to determine valence electrons. (must subtract 10 from groups 13-18)