Developments of Periodic Table Design

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Questions and Answers

What was Henry Moseley's contribution to the periodic table?

He arranged the elements in order of their atomic masses.

He developed the periodic law.

He derived the atomic number from spectroscopic measurements. (correct)

He predicted the properties of undiscovered elements.

What was Mendeleev's periodic law based on?

Atomic numbers

Chemical properties

Atomic masses (correct)

Physical properties

What was the arrangement of elements in Mendeleev's periodic table?

In vertical columns called periods and horizontal rows called groups

In alphabetical order

In order of their atomic numbers

In horizontal rows called periods and vertical columns called groups (correct)

Why did Mendeleev leave vacant spaces in his periodic table?

Because he predicted the existence of undiscovered elements Signup and view all the answers

What was the significance of Mendeleev's correction of atomic masses?

It helped him arrange elements in the correct order Signup and view all the answers

What was the purpose of Newland's and Mendeleev's tables?

To organize elements based on their properties Signup and view all the answers

What was the format of Mendeleev's periodic table?

Eight-column format in order of increasing atomic mass Signup and view all the answers

What did Mendeleev assume about the spaces in his periodic table?

They corresponded to unknown elements Signup and view all the answers

What was the name given by Mendeleev to the element between silicon and tin?

Eka-silicon Signup and view all the answers

What was one of the major problems with Mendeleev's periodic table?

All of the above Signup and view all the answers

What were some of the issues with the elements in the same group in Mendeleev's table?

They had different chemical reactivity Signup and view all the answers

What did Lothar Meyer publish four months after Mendeleev?

A report on the periodic relationship Signup and view all the answers

What did Mendeleev predict about the properties of germanium?

It would have properties similar to silicon and tin Signup and view all the answers

What was the main goal of scientists around 200 years ago?

To predict the properties of elements during chemical reactions Signup and view all the answers

What did Johann Döbereiner notice among various groups of three elements?

Similarities in their properties Signup and view all the answers

What did Dobereiner discover about the atomic mass of the middle element in each triad?

It was close to the average of atomic masses of the other two elements Signup and view all the answers

What did John Newlands realize in 1865?

That a cycle of properties repeated with every eight elements Signup and view all the answers

What was the law of octaves?

A cycle of properties that repeated with every eight elements Signup and view all the answers

Who published a periodic table that made the crucial advance of using the law of octaves as a predictive tool?

Dmitri Mendeleev Signup and view all the answers

What was the main contribution of Dmitri Mendeleev to the development of the periodic table?

The use of the law of octaves as a predictive tool Signup and view all the answers

What was the significance of the work of Dmitri Mendeleev?

It helped to develop a tool for predicting the properties of elements during chemical reactions Signup and view all the answers

Study Notes

Developments of Periodic Table Design

In 1829, Johann Döbereiner discovered similarities in properties among groups of three elements, which he called "triads".
Döbereiner found that the atomic mass of the middle element in each triad was close to the average of atomic masses of the other two elements.

John Newlands and the Law of Octaves

In 1865, John Newlands realized that the elements, when placed in order of increasing atomic weights, showed a cycle of properties repeating every eight elements, which he called the "law of octaves".

Dmitri Mendeleev and the Periodic Table

In 1869, Dmitri Mendeleev published a periodic table that used the law of octaves as a predictive tool.
Mendeleev's table organized elements in an eight-column format in order of increasing atomic mass, with each eighth element having similar properties.
He left spaces for unknown elements and predicted their properties based on the chemistry of neighboring elements.

Predicting Unknown Elements

Mendeleev's predictions included the properties of the missing element between silicon and tin, called eka-silicon (Es), which were later found to match the properties of germanium.

Limitations of Mendeleev's Table

The table had three major problems: elements did not always fit in the group with matching properties, new elements were being discovered with no space in the table, and elements in the same group had different chemical reactivity.

Henry Moseley and the Modern Periodic Table

Henry Moseley's work provided the crucial transition to the modern periodic table by placing elements in order of atomic number, removing irregularities, and defining exactly the spaces where elements still needed to be found.

Mendeleev's Periodic Law

Mendeleev's periodic law states that the physical and chemical properties of elements are a periodic function of their atomic masses.
He arranged elements in increasing order of atomic masses in horizontal rows (periods) and vertical columns (groups).

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Description

Learn about the history and developments of the periodic table, a crucial tool in chemistry. From its origins to modern designs, understand how scientists categorized elements and their properties.