How does a deck of cards and world map relate to the periodic table?

How does a deck of cards and world map relate to the periodic table?

THE PERIODIC TABLECh 5.1 – Finding Order

Until 1750 - Only 17 elements had been

identified Mainly metals - such as copper and

iron. Alchemists Natural abundance

As the number of known elements grew, so did the need to organize and present them in a universal manner.

The Search for Order

The Search for Order In 1789 - Antoine Lavoisier

Grouped the known elements into 4 categories Metals Nonmetals Gases Earths

For the next 80 years, scientists looked for different ways to classify the elements. But no system worked for all the known elements.

Mendeleev’s Proposal1869 - Dmitri Mendeleev developed an approach for organizing the elements while playing a game solitaire.

Making observations about how the cards were sorted (by suit and value) provided Mendeleev with an idea

Mendeleev’s Periodic Table

Mendeleev’s Periodic Table

Mendeleev made a “deck of cards” of the elements ~60 known elements Listed on each card - an element’s

Name Mass Properties

Mendeleev lined up the cards in order of increasing mass A new pattern emerged

New Pattern The key was to break the elements

into rows. Continued creating a row based on

increasing mass until he came across an element with properties similar to those of one already in the row

Started a new row Elements with similar properties

were organized in columns

Mendeleev’s Periodic Table

Mendeleev’s Periodic Table

How did Mendeleev organize the elements in his periodic table? He arranged the elements into rows

in order of increasing mass so that elements with similar properties were in the same column.

Mendeleev’s Periodic Table

The final arrangement was similar to a winning arrangement in solitaire: Columns were organized by properties (suits) Within a column, the masses increased from top

to bottom (value). Trend – Mass Increases from left to right & top to bottom

Mendeleev’s chart became the 1st universal periodic table. A periodic table is an arrangement of elements

in columns, based on a set of properties that repeat from row to row.

Mendeleev’s Periodic Table

Mendeleev’s PredictionAt the time Mendeleev made his table, many elements had not yet been discovered. When he placed the elements where their properties fit, there were several gaps in the table.

Confident that gaps would be filled by NEW elements

Mendeleev’s Periodic Table

Mendeleev’s PredictionHe used the properties of elements located near the gaps in his table to predict properties for undiscovered elements.

Able to offer the best explanation for how the properties of an element were related to its location in his table.

Some scientists didn’t accept those predictions.Others used the predictions to help in their search for undiscovered elements.

Mendeleev’s Periodic Table

Evidence Supporting Mendeleev’s Table The close match between Mendeleev’s

predictions and the actual properties of new elements showed how useful his periodic table could be.

Mendeleev named missing elements after elements in the same group. He gave the name eka-aluminum to the missing

element one space below aluminum in the table. Mendeleev predicted that eka-aluminum would

be a soft metal have a low melting point have a density of 5.9 g/cm3

In 1875, a French chemist discovered a new element.

He named the element gallium (Ga) in honor of France. (The Latin name for France is Gallia.)

Gallium is a soft metal has a melting point of 29.7°C

So low a persons body heat will melt it has a density of 5.91 g/cm3

Evidence Supporting Mendeleev’s Table

The discovery of other elements and their properties provided even further evidence to support Mendeleev’s design. Scandium (Sc) in 1879 Germanium (Ge) in 1886

Today scientists use the periodic table to explain the chemical behavior of different groups of elements

Evidence Supporting Mendeleev’s Table

Assessment Questions

1. How many elements were discovered between1750 and the 1869?

a. ~20b. ~40c. ~30d. ~60

Assessment Questions

2. Following his observations, Mendeleev began organizing the elements by lining them up in order of

a. Decreasing massb. Increasing atomic numberc. Increasing massd. Increasing melting point

Assessment Questions

3. 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.

Assessment Questions

4. Mendeleev made predictions regarding the gaps in his table by

a. Using only the masses of the surrounding known elements

b. Using the known elements subatomic particles

c. Using only the known elements melting points

d. Using all the various properties of the known elements surrounding the gaps

Assessment Questions

5. For which element did Mendeleev correctly predict the properties even before it had been discovered?

a. galliumb. hydrogenc. bromined. aluminum