Chemistry
Periodic Classification and Elements
1,176 Questions
Periodic classification organizes chemical elements based on atomic structure, periodic laws, and elemental properties. It covers historical classification systems, electron configurations, and periodic trends. Test takers preparing for chemistry sections will find these questions crucial for mastering fundamental element properties and atomic interactions.
Periodic table structureAtomic orbitalsElement identificationPeriodic laws
Periodic Classification and Elements Questions
A
Correct answer
Explanation
The 1st period of the periodic table contains only two elements, hydrogen and helium, making it the shortest period. Subsequent periods contain more elements.
B
Correct answer
Explanation
Dobereiner's law of triads grouped elements into sets of three based on their chemical properties and atomic masses. Each group is known as a triad.
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Left
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Centre and right
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Left and centre
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Right
C
Correct answer
Explanation
In the modern periodic table, metals occupy the left and central parts of the table, while non-metals are generally found on the right side.
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S-block
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P-block
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D-block
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F-block
D
Correct answer
Explanation
Lanthanides and actinides are known as inner transition elements and are placed in the f-block at the bottom of the periodic table.
C
Correct answer
Explanation
The 6th and 7th periods are considered incomplete because they contain elements that were discovered later or are synthetic, and the 7th period is still being filled.
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Atomic number
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Atomic mass
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Density
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None of these
D
Correct answer
Explanation
Atomic mass of an element can vary.
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Left
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Right
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Adjacent to noble gases
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Between metals and non - metals
D
Correct answer
Explanation
Metalloids are found along the diagonal line separating metals on the left and non-metals on the right in the p-block of the periodic table.
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mass number
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atomic number
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atomic mass
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physical properties
C
Correct answer
Explanation
Dobereiner classified elements into triads based on their atomic masses, where the middle element had an atomic mass approximately equal to the average of the other two.
B
Correct answer
Explanation
Group 1 contains the alkali metals (Lithium, Sodium, Potassium, Rubidium, Cesium, Francium) and Hydrogen, which is a non-metal.
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Period 6
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Group 8
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Period 7
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Group 18
D
Correct answer
Explanation
Noble gases are located in Group 18 of the modern periodic table, characterized by having a full valence shell.
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Dobereiher's
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Newlands Law of Octaves
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Mendelleev's Periodic table
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Modern periodic table
C
Correct answer
Explanation
Mendeleev's periodic table could not explain the position of isotopes because it was based on atomic masses. Isotopes have different atomic masses but the same atomic number, so they would occupy different positions in Mendeleev's table but should occupy the same position.
D
Correct answer
Explanation
In the 5th period, there are a total of 32 elements.
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periods, groups
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groups, periods
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lanthanides, actinides
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actinides, lanthanides
A
Correct answer
Explanation
The horizontal rows of elements in a modern periodic table are called periods and the vertical rows of elements in a periodic table are called groups. There are total 7 periods and 18 groups in modern periodic table.
B
Correct answer
Explanation
For 4s orbital, n = 4, l = 0, m = 0
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main energy level
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spin angular momentum
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orbital angular momentum
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orientation of the orbital in space
A
Correct answer
Explanation
The principal quantum number of an atom is related to the main energy level.