Tag: classification of elements- the periodic table

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Questions Related to classification of elements- the periodic table

Multiple choice chemistry classification of elements- the periodic table introduction to periodic table necessity of classification need for classification

Classification of periodic table based on atomic number is given by:

  1. Mendeleev's

  2. Mosley

  3. Both A and B

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Henry Moseley found a relationship between the X-ray wavelength of an element and its atomic number. Moseley's discovery showed that atomic numbers were in fact based upon experimental measurements.

Multiple choice chemistry classification of elements- the periodic table development of the modern periodic table into the history mendeleef's periodic table

The first attempt to classify elements systemically was made by :

  1. Mendeleev

  2. Newland

  3. Lother Meyer

  4. Dobereiner
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The first attempt to classify elements systemically was made by Dobereiner.
The triads of elements that showed similar chemical properties.
Other properties of the elements followed trends in which the value of the middle element of the triad was in between those of the end members.

Multiple choice chemistry classification of elements- the periodic table development of the modern periodic table into the history mendeleef's periodic table

The arrangement of elements in a group of three is known as Law of Triads.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Johann Wolfgang Dobereiner proposed the Law of Triads, which grouped elements with similar properties into sets of three where the atomic mass of the middle element was approximately the average of the other two.

Multiple choice chemistry classification of elements- the periodic table development of the modern periodic table into the history mendeleef's periodic table

The atomic masses of Li and K are 7 and 39, respectively. According to law of triads the atomic mass of Na will be:

  1. 23

  2. 32

  3. 46

  4. 64
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Dobereiner arranged the elements in increasing order of atomic masses. He found that the atomic mass of the middle element was approximately equal to the arithmetic mean (average) of the atomic masses of the other two elements of that triad when they are arranged in their increasing order of atomic mass.

So Li=7,K=39

Atomic mass of Na = $\dfrac{7+39}{2}=\dfrac{46}{2}=23$