The Periodic Table Part One

The Basics What does periodic mean? Having or marked by repeated cycles What things in our everyday life do we notice as cyclic or periodic? What are some of the patterns you notice on the periodic table? There are many important people who played a key role in organizing the elements in such an intricate fashion…

What does periodic mean?

Having or marked by repeated cycles

What things in our everyday life do we notice as cyclic or periodic?

What are some of the patterns you notice on the periodic table?

There are many important people who played a key role in organizing the elements in such an intricate fashion…

Antoine Lavoisier (1790’s) Compiled a list of known elements at the time (23) What elements do you think were included here? Gold, silver, oxygen, carbon The 1800’s brought about big changes…

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

What elements do you think were included here?

Gold, silver, oxygen, carbon

The 1800’s brought about big changes…

What are some big things that may have affected the knowledge of chemistry? Electricity Development of the spectrometer Industrial revolution (mid-1800’s) Lead to many chemical industries…soaps, dyes, fertilizers But not all good things came from the revolution Chemical pollution now an issue 70 known elements by the 1870

What are some big things that may have affected the knowledge of chemistry?

Electricity

Development of the spectrometer

Industrial revolution (mid-1800’s)

Lead to many chemical industries…soaps, dyes, fertilizers

But not all good things came from the revolution

Chemical pollution now an issue

70 known elements by the 1870

In addition to new elements… New scientific data that provided insight into the properties of compounds and elements A tool for organization became necessary Big step: 1860 Scientists agreed on a method for accurately determining the atomic masses of the elements (finally!) What would be the problem with not having a universal way to measure the mass of elements? Now the search for relationships between mass and elements was on…

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

A tool for organization became necessary

Big step: 1860

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

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

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

John Newlands (1864) English chemist Proposed organization scheme Noticed elements were arranged by increasing atomic mass Also, their properties repeated every eigth element 1 st and 8 th 2 nd and 9 th What do were call this repeating pattern? Newlands called it: The Law of Octaves Octave is a group of musical notes that repeats every eighth tone

English chemist

Proposed organization scheme

Noticed elements were arranged by increasing atomic mass

Also, their properties repeated every eigth element

1 st and 8 th

2 nd and 9 th

What do were call this repeating pattern?

Newlands called it: The Law of Octaves

Octave is a group of musical notes that repeats every eighth tone

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

Newlands organized the first 14 known elements

Elements with similar properties were in the same row

How does this compare with our current periodic table

The Law of octaves was not readily accepted b/c it did not work with all elements Newlands law was also criticized b/c the use of the word octave was considered very “unscientific” The important thing was that Newland recognized that properties of elements were repeated

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

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

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

Lothar Meyer (1869) German chemist Demonstrated connection between atomic mass and elemental properties Did not receive as much credit as Dmitri Mendeleev because he did not publish his organization scheme first

German chemist

Demonstrated connection between atomic mass and elemental properties

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

Dmitri Mendeleev (1869) Russian chemist demonstrated connection between atomic mass and elemental properties Noticed (like Newlands) that when elements were put in order of atomic mass there was a periodic repetition of their elemental properties Arranged elements in order of increasing atomic mass into columns with similar properties This was the first periodic table

Russian chemist demonstrated connection between atomic mass and elemental properties

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

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

This was the first periodic table

Mendeleev’s table was widely accepted because it predicted the existence and properties of undiscovered elements Blank spaces on the table Predicted properties of yet to be discovered elements such as scandium, gallium, and germanium

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

Blank spaces on the table

Predicted properties of yet to be discovered elements such as scandium, gallium, and germanium

But there were problems… New elements discovered and atomic masses were more accurately determined Elements in Mendeleev’s table not in correct order Arranging elements by mass now put groups of elements together with different properties

New elements discovered and atomic masses were more accurately determined

Elements in Mendeleev’s table not in correct order

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

Henry Moseley (1913) English Chemist Figured out the problem with Medeleev’s Table What did Moseley Discover before? Atoms of each element contain unique number of protons in their nuclei He arranged elements in order of increasing atomic number and not increasing atomic mass

English Chemist

Figured out the problem with Medeleev’s Table

What did Moseley Discover before?

Atoms of each element contain unique number of protons in their nuclei

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

Problem Solved! Moseley’s arrangement solved the problems with Mendeleev’s table His arrangement resulted in clear periodic patterns of properties Lead to Periodic Law: Statement that there is a periodic repetition of chemical and physical properties of the elements when they are arranged in increasing atomic number

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

His arrangement resulted in clear periodic patterns of properties

Lead to Periodic Law:

Statement that there is a periodic repetition of chemical and physical properties of the elements when they are arranged in increasing atomic number

Problem-solving lab p 155

Modern Periodic Table