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Questions and Answers
Which element is considered similar to lithium (Li) according to Newlands' Law of Octaves?
Which element is considered similar to lithium (Li) according to Newlands' Law of Octaves?
- Calcium (Ca)
- Potassium (K)
- Beryllium (Be)
- Sodium (Na) (correct)
Newlands' Law of Octaves is applicable to all known elements at that time.
Newlands' Law of Octaves is applicable to all known elements at that time.
False (B)
What is the significance of atomic mass in Newlands' classification method?
What is the significance of atomic mass in Newlands' classification method?
Atomic mass was made the basis of classification.
According to Newlands' Law of Octaves, every ______ element exhibits properties similar to the first one.
According to Newlands' Law of Octaves, every ______ element exhibits properties similar to the first one.
Match the following elements with their corresponding atomic masses according to Newlands’ Law of Octaves:
Match the following elements with their corresponding atomic masses according to Newlands’ Law of Octaves:
What did Mendeleev emphasize when classifying elements?
What did Mendeleev emphasize when classifying elements?
Mendeleev arranged the elements based on their atomic numbers.
Mendeleev arranged the elements based on their atomic numbers.
What is the statement known as Mendeleev's Periodic Law?
What is the statement known as Mendeleev's Periodic Law?
Mendeleev left vacant positions in his periodic table for elements that were yet to be __________.
Mendeleev left vacant positions in his periodic table for elements that were yet to be __________.
Match the following terms with their descriptions:
Match the following terms with their descriptions:
Flashcards
Mendeleev's Periodic Law
Mendeleev's Periodic Law
Mendeleev's Periodic Law states that the chemical and physical properties of elements repeat in a regular pattern when arranged in increasing order of their atomic masses.
Mendeleev's Periodic Table
Mendeleev's Periodic Table
Mendeleev's Periodic Table is a tabular arrangement of elements based on their atomic masses and properties, with elements having similar properties placed in the same column.
Why Mendeleev's classification was successful
Why Mendeleev's classification was successful
Mendeleev's success was due to his focus on the properties of elements over the atomic masses, allowing him to leave gaps for undiscovered elements and predict their properties.
Predictive power of Mendeleev's Periodic Table
Predictive power of Mendeleev's Periodic Table
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Mendeleev's contribution to chemistry
Mendeleev's contribution to chemistry
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What is the Law of Octaves?
What is the Law of Octaves?
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What were the shortcomings of the Law of Octaves?
What were the shortcomings of the Law of Octaves?
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What are the merits of Newlands' Law?
What are the merits of Newlands' Law?
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How did Newlands arrange elements in his Law of Octaves?
How did Newlands arrange elements in his Law of Octaves?
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What was the main goal of Newlands' Law of Octaves?
What was the main goal of Newlands' Law of Octaves?
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Study Notes
Periodic Classification of Elements
- Elements with similar electronic configurations share similar chemical properties
- By the mid-1800s, nearly 60 elements were known. A need for systematic classification arose
- Early classifications included grouping elements as metals and non-metals, but this was limited.
- Dobereiner's triads: Grouping elements with similar properties into sets of three (e.g., lithium, sodium, potassium). Atomic mass of the middle element was roughly the average of the other two.
- Newlands' law of octaves: Arranging elements in increasing order of atomic mass, observing similar properties repeating every eighth element. Limited to elements with low atomic numbers.
- Mendeleev's periodic table: Arranging elements in order of increasing atomic mass; elements with similar properties are placed in columns (groups).Left blank spaces to predict new elements.
- Based on atomic weight, but some anomalies remained.
- Modern periodic table: Arranging elements in order of increasing atomic number.
- Basis now atomic number rather than atomic mass
- Elements are arranged by similar properties with gaps showing undiscovered elements. Predicting their properties.
Modern Periodic Law
- Chemical and physical properties of elements are a periodic function of their atomic numbers.
- Atomic number is the number of protons in the nucleus of an atom.
- Modern periodic table reflects the periodicity of properties based on atomic numbers.
- Main features include: periods and groups.
Periodic Properties
- Atomic size: The distance from the nucleus to the outermost electron shell.
- Decreases across a period (left to right) due to increasing nuclear charge.
- Increases down a group due to increasing number of electron shells.
- Metallic character: The tendency to lose electrons and form positive ions (cations).
- Decreases across a period (left to right) due to increasing nuclear charge.
- Increases down a group due to increasing atomic size and decreased effective nuclear charge.
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