5.1 Organizing the Elements
5-1
• The Search for order
– Why did they begin to organize the elements?
– How did they start the organization?
• Mendeleev's Periodic Table.
– Mendeleev’s Proposal
• How did he arrange it?
• What made him come up with the arrangement?
• Mendeleev’s Prediction
• Evidence Supporting Mendeleev’s table
5.1 Organizing the Elements
5-1
• The Search for order
– Why did they begin to organize the elements?
– How did they start the organization?
• Mendeleev's Periodic Table.
– Mendeleev’s Proposal
• How did he arrange it?
• What made him come up with the arrangement?
• Mendeleev’s Prediction
• Evidence Supporting Mendeleev’s table
5.1 Organizing the Elements
5-1
• The Search for order
– Why did they begin to organize the elements?
– How did they start the organization?
• Mendeleev's Periodic Table.
– Mendeleev’s Proposal
• How did he arrange it?
• What made him come up with the arrangement?
• Mendeleev’s Prediction
• Evidence Supporting Mendeleev’s table
5.1 Organizing the Elements
5-1
• The Search for order
– Why did they begin to organize the elements?
– How did they start the organization?
• Mendeleev's Periodic Table.
– Mendeleev’s Proposal
• How did he arrange it?
• What made him come up with the arrangement?
• Mendeleev’s Prediction
• Evidence Supporting Mendeleev’s table
5.1 Organizing the Elements
5-1
• The Search for order
– Why did they begin to organize the elements?
– How did they start the organization?
• Mendeleev's Periodic Table.
– Mendeleev’s Proposal
• How did he arrange it?
• What made him come up with the arrangement?
• Mendeleev’s Prediction
• Evidence Supporting Mendeleev’s table
5.1 Organizing the Elements
5-1
• The Search for order
– Why did they begin to organize the elements?
– How did they start the organization?
• Mendeleev's Periodic Table.
– Mendeleev’s Proposal
• How did he arrange it?
• What made him come up with the arrangement?
• Mendeleev’s Prediction
• Evidence Supporting Mendeleev’s table
5.1 Organizing the Elements
Periodic songs and videos
• Tom LehrerLobachevshy
• They Might Be
Giants
• Harry Potter
5.1 Organizing the Elements
In a video store, movies
are in categories such as
Action or Comedy. When
scientists organized the
elements, they had to
decide what categories to
use and where to place
each element. An
organized table of the
elements is one of the
most useful tools in
chemistry.
5.1 Organizing the Elements
I.
Organizing the Elements
A. The Search for Order
1. Until 1750, scientists had identified only 17
elements, mainly metals, such as copper and iron.
2. In 1789, Antoine Lavoisier grouped the known
elements into categories he called metals,
nonmetals, gases, and earths.
3. For the next 80 years, scientists looked for
different ways to classify the elements. But no
system worked for all the known elements.
5.1 Organizing the Elements
Mendeleev’s Periodic Table
Mendeleev’s Proposal
In the 1860s, Dmitri
Mendeleev developed an
approach for organizing
the elements while playing
the card game solitaire. In
this game, the player sorts
a deck of cards
by suit and value.
5.1 Organizing the Elements
Mendeleev’s Periodic Table
Mendeleev made a “deck of cards” of the elements, listing an element’s
name, mass, and properties on each card. When Mendeleev lined up the
cards in order of increasing mass, a pattern emerged. The key was to break
the elements into rows.
5.1 Organizing the Elements
4. Mendeleev’s Proposal
a. Elements in columns were organized by properties
b. Within a column, the elements masses increased from
top to bottom
c. His chart was a periodic table- an arrangement of
elements in columns, based on a set of properties that
repeat from row to row.
1) A calendar is another example of a periodic table
5.1 Organizing the Elements
5. Mendeleev’s Prediction
a. Mendeleev was able to offer the best explanation
for how the properties of an element were related
to its location in his table.
b. When he placed the elements where their properties
fit, there were several gaps in the table.
c. He used the properties of elements located near the
blank spaces in his table to predict properties for
undiscovered elements.
5.1 Organizing the Elements
Mendeleev’s Periodic Table
Mendeleev was confident that the gaps in his
table would be filled by new elements.
Some scientists didn’t accept those
predictions. Others used the predictions to
help in their search for undiscovered elements.
5.1 Organizing the Elements
6. Evidence Supporting Mendeleev’s Table
a. The close match between Mendeleev’s predictions and
the actual properties of new elements showed how useful
his periodic table could be.
b. Mendeleev named missing elements after elements in the
same group.
1) He named a missing element one space below
aluminum eka-aluminum
2) He predicted the properties to be
a) A soft metal
b) Low melting point
c) Density about 5.9 g/cm3
5.1 Organizing the Elements
c. In 1875, a French chemist discovered a new element and
named it gallium (Ga) in honor of France.
1) The properties were:
a) is a soft metal,
b) has a melting point of 29.7°C, and
c) has a density of 5.91 g/cm3.
5.1 Organizing the Elements
Mendeleev’s Periodic Table
Heat from a person's hand can melt gallium.
In some traffic signals, there are tiny light
emitting diodes (LEDs) that contain a
compound of gallium.
5.1 Organizing the Elements
d. Scientists use the periodic table to explain the chemical
behavior of different groups of elements.
1) The discovery of scandium (Sc) in 1879 and the
discovery of germanium (Ge) in 1886 provided more
evidence.
5.1 Organizing the Elements
Assessment Questions
1. In Mendeleev’s periodic table, elements with
similar properties were grouped
a. in the same row.
b. in the same column.
c. in diagonal lines that run from top left to the bottom
right.
d. in pairs of two.
5.1 Organizing the Elements
Assessment Questions
1. In Mendeleev’s periodic table, elements with
similar properties were grouped
a. in the same row.
b. in the same column.
c. in diagonal lines that run from top left to the bottom
right.
d. in pairs of two.
ANS: B
5.1 Organizing the Elements
Assessment Questions
2. For which element did Mendeleev correctly predict
the properties even before it had been
discovered?
a.
b.
c.
d.
gallium
hydrogen
bromine
aluminum
5.1 Organizing the Elements
Assessment Questions
2. For which element did Mendeleev correctly predict
the properties even before it had been
discovered?
a.
b.
c.
d.
gallium
hydrogen
bromine
aluminum
ANS:
A