Problem 40 What is the basic difference bet... [FREE SOLUTION]

Chapter 4: Problem 40

What is the basic difference between Mendeleeff's periodic table and modern periodic table?

Short Answer

Expert verified

Short Answer: The primary difference between Mendeleev's periodic table and the modern periodic table is their organizing principle. Mendeleev's table arranged elements based on atomic masses, while the modern periodic table arranges them based on atomic numbers. The modern periodic table is considered more accurate because it reflects the elements' electronic configurations, leading to a better understanding of their periodic properties, reactivity, and trends within groups and periods. Additionally, it is more effective at predicting properties of newly discovered elements.

Step by step solution

Understand Mendeleev's Periodic Table

Mendeleev's periodic table was developed by Dmitri Mendeleev in 1869. In this table, elements were arranged in increasing order of their atomic masses. Mendeleev organized the elements in a way that elements with similar properties were placed in the same group (column), thereby highlighting the periodicity of the elements' properties.

Understand the Modern Periodic Table

The modern periodic table is based on the work of many scientists, but it is primarily attributed to Henry Moseley's work in 1913. In the modern periodic table, elements are arranged in increasing order of their atomic numbers (number of protons in the nucleus). The atomic number provides a clearer and more reliable method of organizing elements, as it results in the arrangement of elements based on their electronic configurations.

Identifying the Basic Difference

The primary difference between Mendeleev's and the modern periodic table is the organizing principle. In Mendeleev's table, elements were arranged based on their atomic masses, while in the modern periodic table, elements are organized by their atomic numbers. This difference means that each element's position in the modern periodic table reflects its electronic configuration, leading to a more accurate representation of the periodic properties of elements.

Importance of the Modern Periodic Table

The modern periodic table is more accurate than Mendeleev's periodic table because it is based on atomic numbers. This organization results in a better understanding of the chemical properties of elements, their reactivity, and trends within groups and periods. The modern periodic table is also better at predicting the properties of newly discovered elements or elements not yet discovered during Mendeleev's time.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Mendeleev's Periodic Table

Dmitri Mendeleev developed his version of the periodic table in 1869. He arranged the elements by increasing atomic mass. This was innovative because it showcased the periodic nature of chemical properties. Mendeleev's table organized elements into groups (vertical columns) where elements with similar properties lined up together. One of Mendeleev's major accomplishments was leaving gaps for undiscovered elements. He predicted their properties based on trends he observed. This ability to predict uncharted elements showcased the usefulness of his table in advancing chemistry.

Modern Periodic Table

The modern periodic table advanced the work started by Mendeleev. Henry Moseley, in 1913, reorganized the elements according to their atomic numbers. The atomic number is defined as the number of protons in an atom's nucleus. This shifted the organization principle from atomic mass to atomic number. This change resulted in a more precise arrangement since atomic number correlates directly with an element鈥檚 electronic configuration. The modern table reflects a clearer understanding of chemical behavior and periodic trends. It successfully explains natural periodicity of elements without the exceptions encountered using atomic mass.

Atomic Mass

Atomic mass is the mass of an atom, typically expressed in atomic mass units (amu). It roughly represents the sum of protons and neutrons in the atom's nucleus. In Mendeleev's periodic table, it was the factor used to order elements. Using atomic mass had limitations, since isotopes and exceptions could disrupt order. For example, iodine and tellurium, where tellurium is heavier but precedes iodine in the table. Mendeleev had to make adjustments to preserve periodicity which highlighted the need for a more reliable organizing principle.

Atomic Number

Atomic number is the count of protons found in the nucleus of an atom. This value uniquely identifies an element. The adoption of atomic number in the modern periodic table addressed shortcomings of organizing by atomic mass. Elements arranged by atomic number avoid the discrepancies caused by isotopic variations. It also places elements in order where trends in properties such as reactivity, electronegativity, and ionization energy more accurately reflect observed chemical behaviors. This organization allows for more precise scientific predictions and understanding.

Chemical Properties

Chemical properties refer to the reactivity and behavior of an element with other substances. Elements with similar chemical properties often fall into the same groups in the periodic table. For example, noble gases are known for their lack of reactivity due to their full valence shell of electrons. Both Mendeleev's and the modern periodic table use these properties to group elements. This grouping provides insights into reactivity and potential chemical reactions. Understanding chemical properties is crucial for predicting how elements interact and is essential for the study of chemistry as a whole.

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What is the basic difference between Mendeleeff's periodic table and modern periodic table?

Short Answer

Step by step solution

Understand Mendeleev's Periodic Table

Understand the Modern Periodic Table

Identifying the Basic Difference

Importance of the Modern Periodic Table

Key Concepts

Mendeleev's Periodic Table

Modern Periodic Table

Atomic Mass

Atomic Number

Chemical Properties

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