CHAPTER 5 PERIODIC TABLE Periodic Law and Electron Configurations The “first” Periodic Table of the Elements most credit given to ______________________ when? ________ (about ________ elements known) he arranged the elements by __________________________ and grouped them according to ________________________ he gets the most credit because he dealt with two important issues… to group the elements with respect to their similar properties, 1. he had to ____________________________________ predicted (correctly) ___________________________ 2. and he had to ___________________________________ _________________________________________ predicted (incorrectly) _______________________ Dmitri Mendeleev 1860’s 60 increasing atomic mass similar properties leave blanks in his periodic table blanks corresponded to elements yet to be discovered place some elements out of order with respect to mass the masses were incorrect

Periodic Table “from the 19th century” – pg 161 in text ???????? atomic number established in 1913 (Moseley) atomic mass ????? just an ordering number…. “out of order” Mendeleev

without any understanding of atomic structure Mendeleev was “so close” to right…

an integer number of positively charged particles (protons) not until 1913 (some 55+ years later!) was the mass issue resolved… Moseley (working in ___________________ lab) determined the nucleus contained ______________________________ his work established the ___________________ _______________________________________ symbol ________ called ___________________ Rutherford’s an integer number of positively charged particles (protons) number of protons in the nuclei of atoms Z atomic number so, again, some 55 years after Mendeleev’s work, the Periodic Law of the Elements was established… what was important was not ordering the elements with respect to mass BUT with respect to _____________________ atomic number

The Periodic Law of the Elements When the elements are ordered with respect to increasing atomic number, their physical and chemical properties show a periodic pattern periodic – repeating at certain (predictable) intervals - after every so many (8, 8, 18, 18, 32, 32 …) elements, there is another element with similar properties the elements with similar properties are grouped into columns

noble gases alkali metals halogens alkaline earth metals coinage metals

The Periodic Law of the Elements When the elements are ordered with respect to increasing atomic number, their physical and chemical properties show a periodic pattern periodic – repeating at certain (predictable) intervals 1913 - after every so many (8, 18, 32…) elements, there is another element with similar properties - the elements with similar properties are grouped into columns (reminder… a (Scientific) Law lacks an ____________________) explanation the explanation for the Periodic Law of the Elements lies in Atomic Theory (the structure of the atom) the explanation for the groupings of the elements is that elements in a group have similar properties BECAUSE they have similar outer shell electron configurations 1927 Schrodinger model so… if we know the electron configurations we can predict and explain the properties of the elements

some patterns noted so far… the outer shell corresponds to the row in the Periodic Table the outer shell starts to be filled with the element in the 1st column and the outer shell is full with the element in the last column so, determine the ground state electron configuration patterns for each group (column) of elements focus on outer shell because it is those electrons that have the greatest influence on properties