Moseley and Mendeleev's Atomic Theory

Questions and Answers

Moseley's work confirmed Mendeleev's belief that atomic weights were the primary factor determining an element's properties.

False

Mendeleev's periodic table was completely replaced by Moseley's.

False

X-rays played a crucial role in Moseley's discovery

True

What was the primary basis for arranging elements in Mendeleev's periodic table?

atomic mass Signup and view all the answers

Who discovered that the properties of elements are more closely related to their atomic number than their atomic mass?

Moseley Signup and view all the answers

The modern periodic table is primarily arranged based on

atomic number Signup and view all the answers

What is the significance of energy sub-levels in the modern periodic table?

They influence the element's chemical properties. Signup and view all the answers

Which scientist first proposed leaving gaps in the periodic table for undiscovered elements?

Mendeleev Signup and view all the answers

How do the elements in the modern periodic table differ from those in Mendeleev's table?

All of the above. Signup and view all the answers

Which of the following is NOT true about the modern periodic table?

It is arranged in order of increasing atomic mass Signup and view all the answers

Study Notes

Mendeleev's Periodic Table

Arranged elements primarily based on atomic weights.
Mendeleev believed atomic weight was the key factor influencing an element's properties.
The table included gaps for undiscovered elements, anticipating their existence and properties.

Moseley's Contributions

Demonstrated that properties of elements relate more closely to atomic number than atomic mass.
Replaced Mendeleev's periodic table with a more accurate arrangement based on atomic number.
Utilized X-rays to discover atomic numbers, leading to a redefinition of the periodic law.

Modern Periodic Table

Organized primarily by atomic number, a shift from the earlier emphasis on atomic mass.
Displays elements in order of increasing atomic number, improving the relationship between elemental properties.
Introduces energy sub-levels, which categorize elements within blocks (s, p, d, f) based on electron configurations, explaining the periodic trends.

Significant Scientists

Mendeleev first proposed the concept of gaps for undiscovered elements in the periodic table.
Moseley is credited with solidifying the concept of atomic number as a fundamental property for periodic classification.

Differences Between Tables

Modern periodic table provides a more systematic and accurate representation of elemental relationships compared to Mendeleev’s earlier version.
Elements are grouped in a way that reflects consistent patterns in the properties and behaviors of grouped elements.

Misconceptions about the Modern Table

Any assertion claiming the modern periodic table is arranged solely by atomic mass is incorrect; it is fundamentally based on atomic number.

Description

This quiz explores the contributions of Moseley and Mendeleev to atomic theory. Focus is given to how Moseley confirmed Mendeleev's belief regarding atomic weights as a determining factor for the properties of elements. Test your knowledge of their groundbreaking work in chemistry.