Section 4.4—The Periodic Table

History of the Periodic Table Different scientists organized the elements differently—this lead to confusion In 1869, Dimitri Mendeleev designed a periodic table based on atomic mass.  This way showed patterns in properties that repeated across rows and similarities down columns He couldn’t find elements to fit all the property trends, so he left holes

History of the Periodic Table The holes he left were later filled in as more elements were discovered The modern periodic table is arranged by atomic number rather than atomic mass  This caused a few “switches” in placement, but overall is very similar to Mendeleev’s

Organization of the Periodic Table

Groups and Periods Groups Columns are called “groups” or “families” Periods Rows are called “periods”

6 C Carbon Information for Each Element Atomic Number Whole number— elements are ordered by this on the periodic table. Element Symbol If there’s a second letter, it’s lower-case Element Name Atomic Mass Number with decimals Gives the mass for 1 mole of atoms, in grams Most periodic tables give the following information, but it can be in a different location

Parts of the Periodic Table

The rows at the bottom Most periodic tables are written with 2 rows at the bottom. This is done to allow the font to be bigger on a piece of paper.

The rows at the bottom Most periodic tables are written with 2 rows at the bottom. This is done to allow the font to be bigger on a piece of paper. But they really belong here! Follow the atomic numbers on your periodic table to see it!

Electron Configurations and the Periodic Table.

1s 2 2s 2 2p 5 Configurations Within a Group Look at the electron configurations for the Halogens F Cl Br I 1s 2 2s 2 2p 6 3s 2 3p 5 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 5 All of the elements in Group 7 end with 5 electrons in a p subshell. In fact, every Group ends with the same number of electrons in the highest energy subshell

Configurations and the Periodic Table s1s1 s2s2 d1d1 d2d2 d3d3 d4d4 d5d5 d6d6 d7d7 d8d8 d9d9 d 10 p1p1 p2p2 p3p3 p4p4 p5p5 p6p6 f1f1 f2f2 f3f3 f4f4 f5f5 f6f6 f7f7 f8f8 f9f9 f 10 f 11 f 12 f 13 f 14 d-block f-block p-block s-block

p subshells begin in level 2, so begin the p-block with “2p” s subshells begin in level 1, so begin the s-block with “1s” How to remember the filling order? 2p 3p 4p 5p 6p 3d 4d 5d 6d 4f 5f d subshells begin in level 3, so begin the d-block with “3d” f subshells begin in level 4, so begin the f-block with “4f” 1s 2s 3s 4s 5s 6s 7s 1s

To see the filling order of subshells, read from left to right, top to bottom! How to remember the filling order? 2p 3p 4p 5p 6p 3d 4d 5d 6d 4f 5f 1s 2s 3s 4s 5s 6s 7s 1s Note that this tool shows that the 3d energy level is filled after the 4s energy level!

How do you know where to start off after using a noble gas? Use the periodic table! Where Does the Noble Gas Leave Off? 2p 3p 4p 5p 6p 3d 4d 5d 6d 4f 5f 1s 2s 3s 4s 5s 6s 7s He Ne Ar Kr Xe Rn The noble gas fills the subshell that it’s at the end of. Begin filling with the “s” subshell in the next row to show valence electrons.