The Periodic TableThe Periodic Table

Part OnePart One

The BasicsThe Basics

What does periodic mean?What does periodic mean? Having or marked by repeated cyclesHaving or marked by repeated cycles What things in our everyday life do we notice What things in our everyday life do we notice

as cyclic or periodic?as cyclic or periodic? What are some of the patterns you notice What are some of the patterns you notice

on the periodic table?on the periodic table? There are many important people who There are many important people who

played a key role in organizing the played a key role in organizing the elements in such an intricate fashion… elements in such an intricate fashion…

Antoine Lavoisier (1790’s)Antoine Lavoisier (1790’s)

Compiled a list of Compiled a list of known elements at known elements at the time (23)the time (23) What elements do you What elements do you

think were included think were included here?here? Gold, silver, oxygen, Gold, silver, oxygen,

carboncarbon

The 1800’s brought The 1800’s brought about big changes…about big changes…

What are some big things that may have What are some big things that may have affected the knowledge of chemistry?affected the knowledge of chemistry? ElectricityElectricity Development of the spectrometerDevelopment of the spectrometer Industrial revolution (mid-1800’s)Industrial revolution (mid-1800’s)

Lead to many chemical industries…soaps, dyes, Lead to many chemical industries…soaps, dyes, fertilizersfertilizers

But not all good things came from the revolutionBut not all good things came from the revolution Chemical pollution now an issueChemical pollution now an issue

70 known elements by the 187070 known elements by the 1870

In addition to new elements…In addition to new elements…

New scientific data that provided insight into the New scientific data that provided insight into the properties of compounds and elementsproperties of compounds and elements

A tool for organization became necessaryA tool for organization became necessary Big step: 1860Big step: 1860

Scientists agreed on a method for accurately Scientists agreed on a method for accurately determining the atomic masses of the elements determining the atomic masses of the elements (finally!)(finally!)

What would be the problem with not having a What would be the problem with not having a universal way to measure the mass of elements? universal way to measure the mass of elements?

Now the search for relationships between mass Now the search for relationships between mass and elements was on…and elements was on…

John Newlands (1864)John Newlands (1864) English chemistEnglish chemist Proposed organization scheme Proposed organization scheme Noticed elements were arranged by Noticed elements were arranged by

increasing atomic massincreasing atomic mass Also, their properties repeated every Also, their properties repeated every

eigth elementeigth element 11stst and 8 and 8thth

22ndnd and 9 and 9thth

What do were call this repeating What do were call this repeating pattern?pattern?

Newlands called it: The Law of Newlands called it: The Law of OctavesOctaves Octave is a group of musical notes Octave is a group of musical notes

that repeats every eighth tonethat repeats every eighth tone

Newlands organized the first 14 known elements Newlands organized the first 14 known elements Elements with similar properties were in the same rowElements with similar properties were in the same row How does this compare with our current periodic tableHow does this compare with our current periodic table

The Law of octaves was not readily The Law of octaves was not readily accepted b/c it did not work with all accepted b/c it did not work with all elementselements

Newlands law was also criticized b/c the Newlands law was also criticized b/c the use of the word octave was considered use of the word octave was considered very “unscientific”very “unscientific”

The important thing was that Newland The important thing was that Newland recognized that properties of elements recognized that properties of elements were repeatedwere repeated

Lothar Meyer (1869)Lothar Meyer (1869)

German chemistGerman chemist Demonstrated Demonstrated

connection between connection between atomic mass and atomic mass and elemental propertieselemental properties

Did not receive as Did not receive as much credit as Dmitri much credit as Dmitri Mendeleev because Mendeleev because he did not publish his he did not publish his organization scheme organization scheme firstfirst

Dmitri Mendeleev (1869)Dmitri Mendeleev (1869) Russian chemist Russian chemist

demonstrated connection demonstrated connection between atomic mass and between atomic mass and elemental propertieselemental properties

Noticed (like Newlands) that Noticed (like Newlands) that when elements were put in when elements were put in order of atomic mass there order of atomic mass there was a periodic repetition of was a periodic repetition of their elemental propertiestheir elemental properties

Arranged elements in order of Arranged elements in order of increasing atomic mass into increasing atomic mass into columns with similar columns with similar propertiesproperties

This was the first periodic This was the first periodic tabletable

Mendeleev’s table was widely accepted Mendeleev’s table was widely accepted because it predicted the existence and because it predicted the existence and properties of undiscovered elementsproperties of undiscovered elements

Blank spaces on the tableBlank spaces on the table Predicted properties of yet to be Predicted properties of yet to be

discovered elements such as scandium, discovered elements such as scandium, gallium, and germaniumgallium, and germanium

But there were problems…But there were problems…

New elements discovered and atomic New elements discovered and atomic masses were more accurately determinedmasses were more accurately determined

Elements in Mendeleev’s table not in Elements in Mendeleev’s table not in correct ordercorrect order

Arranging elements by mass now put Arranging elements by mass now put groups of elements together with different groups of elements together with different propertiesproperties

Henry Moseley (1913)Henry Moseley (1913)

English ChemistEnglish Chemist Figured out the problem Figured out the problem

with Medeleev’s Tablewith Medeleev’s Table What did Moseley What did Moseley

Discover before?Discover before? Atoms of each element Atoms of each element

contain unique number of contain unique number of protons in their nucleiprotons in their nuclei

He arranged elements in He arranged elements in order of increasing order of increasing atomic atomic number number and not and not increasing atomic massincreasing atomic mass

Problem Solved!Problem Solved!

Moseley’s arrangement solved the Moseley’s arrangement solved the problems with Mendeleev’s tableproblems with Mendeleev’s table

His arrangement resulted in clear periodic His arrangement resulted in clear periodic patterns of propertiespatterns of properties

Lead to Lead to Periodic Law:Periodic Law: Statement that there is a periodic repetition of Statement that there is a periodic repetition of

chemical and physical properties of the chemical and physical properties of the elements when they are arranged in elements when they are arranged in increasing atomic numberincreasing atomic number

Problem-solving lab p 155Problem-solving lab p 155

Modern Periodic TableModern Periodic Table