Chemistry 1 Chapter 6 Modern Periodic Table Last Updated November 24, 2018

Antoine Lavoisier Late 1790s French Scientists Compiled a list of elements Only 23 elements known at the time

John Newlands 1864 English Chemist Proposed an organization scheme for the elements based on increasing atomic mass noting that properties repeated every eighth element. Idea did not work for all elements

Meyer and Mendeleev Meyer-German Chemist Mendeleev-Russian Chemist Mendeleev published his organization scheme first and is therefore given more credit.

Mendeleev Continued Mendeleev arranged elements according to increasing atomic masses but into columns with similar properties Was able to predict the properties of yet undiscovered elements

Not entirely accurate as new elements were discovered and atomic masses of known elements were more accurately determined.

Henry Mosley 1913 English Chemist Arranged elements according to increasing atomic number Resulted in clear Periodic Patterns

Periodic Law The periodic repetition of chemical and physical properties of the elements when they are arranged by increasing atomic number

Review/Discuss Groups – Columns Periods – Rows Main Block Elements (Groups 1A-8A or 1-2,13-18) Transition Elements (Groups 1B-8B or 3-12) 1-18 Newer numbering system for groups

Review/Discuss Continued Metals Non-metals Metalloids Transition Inner Transition Alkali-metals Alkaline Earth Metals Halogens Noble Gases

Classification of the elements Valence e- and the Periodic Table See Figure 6-9 page 160

Blocks s p d f Know the location of each block

Periodic Trends Atomic Radius  in picometers (1 x 10-12 meters) Generally Decreases from left to right and increases as you move down the periodic table

Ion Charged Particle due to loss gain or sharing of electrons Loss of electrons = smaller radius Gain of electrons = larger radius Compare Trends from Fig 6-11 pg 163 to Fig 6-14 pg. 166 Lost e- are generally valence e-

Ions Continued Across Periods moving left to right + ions decrease in size Ions decrease in size Down Groups Both + and – ions increase radii

Ionization Energy- Energy required to remove an e- from a gaseous atom First ionization energy = 1 e- to remove Ionization Energy can be thought of as how strongly an atom’s nucleus holds on to its valence e-

Atoms with large ionization energy are less likely to form + ions Low ionization energy indicates an atom loses e- easily likely to form + ions

Octet Rule- atoms tend to lose, gain or share e- in order to acquire a full set of eight valence e- Electronegativity- ability of an atom to attract e- to itself in a chemical bond Units are arbitrary and are called Paulings, for Linus Pauling

Electronegativity decrease as you move down a group and increases as you move left to right Lowest electronegative = lower left Highest electronegative = upper right