A HISTÓRIA DA TABELA PERIÓDICA | FALA CIENTISTA

Summary

This video delves into the evolution of the periodic table, from its early models to the modern version we use today. It explores the contributions of scientists like Dobereiner, who proposed the Law of Triads, and Mendeleev, who arranged elements by atomic mass, predicting undiscovered elements. Moseley later refined the table by organizing elements by atomic number. The video also explains the periodic properties of elements and the structure of the modern periodic table, highlighting its organization into periods and families, and how these properties vary systematically. It’s an insightful look into how scientific discoveries shaped our understanding of chemistry.

Takeaways

• 😀 The periodic table is a crucial tool for understanding the properties and characteristics of chemical elements.
• 😀 The modern periodic table contains 118 elements, and its organization helps scientists study the elements more efficiently.
• 😀 The periodic table is organized in periods (horizontal rows) and families (vertical columns) based on the similarities in the elements' properties.
• 😀 The first significant model of the periodic table was proposed by Johann Wolfgang Döbereiner in 1829, organizing elements into groups of three based on atomic mass.
• 😀 In 1862, Alexandre-Emile Béguyer de Chancourtois introduced a spiral arrangement of elements, which helped identify periodic properties.
• 😀 John Newlands proposed the 'Law of Octaves' in 1864, where elements were arranged in rows of eight, with properties repeating every eighth element.
• 😀 Dmitri Mendeleev is credited with developing the first widely accepted periodic table in 1868, organizing elements by atomic mass and leaving gaps for undiscovered elements.
• 😀 Mendeleev predicted the properties of elements that would fill the gaps in his table, and many of these predictions were later confirmed.
• 😀 In 1903, Henry Moseley demonstrated that elements should be arranged by atomic number (number of protons) instead of atomic mass, refining the periodic table.
• 😀 The modern periodic table continues to evolve, with the most recent updates in 2016, when elements 113, 115, 117, and 118 were added.
• 😀 The properties of elements, such as atomic radius, ionization energy, and electronegativity, exhibit periodic trends, which repeat at regular intervals in the table.

Q & A

What is the periodic table of elements?

The periodic table of elements is a model that organizes all known chemical elements, displaying their properties and characteristics that repeat periodically. It is a crucial source of information for understanding the behavior and traits of elements.

How many elements are currently in the periodic table?

The current periodic table contains 118 chemical elements, reflecting the elements discovered over time.

Why did scientists begin organizing elements into groups?

Scientists started organizing elements into groups to make the study of chemistry easier and more systematic. They noticed that certain elements shared similar properties, which repeated periodically.

What is the analogy used to explain the periodic nature of the periodic table?

The periodic nature of the periodic table is compared to the Christian calendar, which has 365 days organized into weeks of seven days. Just as activities repeat every week, elements with similar properties repeat in columns of the periodic table.

What was Dobereiner's contribution to the periodic table?

In 1829, German chemist Johann Wolfgang Döbereiner proposed the first periodic table, grouping elements into triads based on similar properties and atomic masses. His model showed that the atomic mass of the central element in each triad was the average of the other two.

What was the Teluric Spiral proposed by Alexandre-Évariste Frédéric d'Osmond?

In 1862, French geologist Alexandre-Évariste Frédéric d'Osmond introduced the Teluric Spiral, organizing elements in increasing atomic mass along a spiral. This arrangement also showed that elements in the same vertical line shared similar chemical properties.

What was the 'Law of Octaves' proposed by John Newlands?

In 1864, English chemist John Newlands developed the 'Law of Octaves', where he arranged elements in rows of eight based on increasing atomic mass. He observed that every eighth element shared similar chemical properties, drawing an analogy to musical notes.

How did Dmitri Mendeleev improve the periodic table?

In 1868, Dmitri Mendeleev organized elements based on increasing atomic mass and placed them in rows and columns according to their chemical properties. He left gaps for undiscovered elements, predicting their properties, which later proved to be accurate.

What significant discovery did Henry Moseley make about the periodic table?

In 1913, English physicist Henry Moseley proved that elements should be arranged by atomic number, not atomic mass. This discovery corrected inconsistencies in Mendeleev’s table and led to the modern arrangement of the periodic table.

How has the periodic table evolved in modern times?

The periodic table has undergone updates over time, with new elements being added as they were discovered. The last major update was in 2016, when elements with atomic numbers 113, 115, 117, and 118 were officially recognized.