The primary difference between the modern periodic table and Mendeleev's periodic table is:a)The two tables are the same except we know about more elements now.b)Mendeleev's table did not arrange the elements according to recurring trends in their properties.c)The elements in the modern table are arranged in order of increasing atomic weight.d)The elements in the modern table are arranged in order of increasing atomic number.Correct answer is option 'D'. Can you explain this answer?

Question

Answer

The primary difference between the modern periodic table and Mendeleev's periodic table is that the elements in the modern table are arranged in order of increasing atomic number. This answer is correct because it accurately reflects the key distinction between the two tables. Let's explore this difference in more detail:

Mendeleev's Periodic Table:
- Dmitri Mendeleev, a Russian chemist, is credited with creating the first periodic table in the late 19th century.
- Mendeleev arranged the elements based on their atomic weights, placing elements with similar properties in the same vertical columns, known as groups or families.
- He left gaps in the table for undiscovered elements and predicted their properties based on the known elements in the same group.
- Although Mendeleev's table was a significant breakthrough, it did not fully account for the observed patterns in the properties of elements.

The Modern Periodic Table:
- The modern periodic table, developed primarily by Henry Moseley in the early 20th century, arranges the elements based on their atomic numbers.
- Atomic number represents the number of protons in an atom's nucleus, which is a fundamental property of elements.
- The elements are organized into horizontal rows, known as periods, and vertical columns, known as groups or families, based on their atomic numbers and recurring patterns in their properties.
- The modern periodic table provides a more accurate representation of the relationships between elements and their properties.
- It also highlights the periodicity of various properties such as atomic radius, ionization energy, electronegativity, and chemical reactivity.

Importance of Atomic Number:
- Atomic number is a more fundamental property of elements than atomic weight.
- Elements can have different isotopes with varying atomic weights but the same number of protons, thus the same atomic number.
- For example, carbon-12 and carbon-14 have different atomic weights but the same atomic number (6).
- By arranging elements based on their atomic numbers, the modern periodic table allows for a more precise understanding of the relationships between elements and their properties.
- It also helps in predicting the properties of newly discovered elements.

In conclusion, the primary difference between the modern periodic table and Mendeleev's periodic table is that the modern table arranges elements in order of increasing atomic number, while Mendeleev's table was based on atomic weights. The modern periodic table provides a more accurate representation of the relationships between elements and their properties, allowing for a deeper understanding of the periodicity of various properties.

Answer

The element cannot be arranged in increasing atomic weight as there are isotopes so mandaleev used atomic number to arrange the elements

Answer

According to lother mayer mandaleef concluded that physical and chemical properties of elements are periodic functions of their atomic weights but later mosleys experiment concluded that frequency directly proportional to atomic no so from that modern periodically table based on atomic no. this is primary difference

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