Dobereiner’s Triads

Q.

Which of the following triads do not follow Dobereiner’s law of triads ?

1. Li, Na, K

2. Ca, Sr, Ba

3. Be, Mg, Ca

4. Cu, Ag, Au

Q.

Lithium(Li), sodium(Na), and potassium(K) were put in the same group on the basis of similar properties.

(a) What are the similarities in their properties.

(b) If the atomic weight of lithium and potassium are 7 and 39 respectively, what is the atomic weight of sodium?

Q.

What was the basis of Dobereiners classification of the elements ?

Q. If elements A, B and C form Dobereiner’s triad and atomic masses of A and middle element B is 40 u and 88 u respectively, then the atomic mass of element C will be

1. 136 u
2. 48 u
3. 128 u
4. 8 u

Q.

Law of Triads is applicable to which set of elements?

Q.

P, Q, and R are the three elements in a Dobereiners triad. If the atomic weight of P is 35.5 and R is 127 then calculate the atomic weight of Q.

Q.

What are the characteristics of Dobereiners triads?

Q.

State Dobereiners Law of Triads for the classification of elements. Support your answer by two examples.

Q.

A group of three elements with similar physical and chemical properties is called ------------

Q.

Dobereiner classified elements into sets of three chemically similar elements called triads.

1. True
2. False

Q.

Write a typical Dobereiner’s triad?

Q.

From the list of elements given below make three triads and name the family of each triad.

Cl, Li, Ca, Sr, I, K, Na, Br, and Ba

Q.

Chlorine, Y, and iodine form a Dobereiners triad. Identify the atomic weight of Y?

Q.

Let’s consider elements X, Y, and Z form a Döbereiner’s triad. If the atomic masses of X and Y are 40 u and 87 u respectively. Find the approximate atomic mass of Z.

1. 140 u
2. 130 u
3. 125 u
4. 134 u

Q. Why was Dobereiner's triad discarded?

Q.

Triads of elements arranged in increasing order of their atomic masses were proposed by-

1. Lothar Meyer

2. Dobereiner

3. Dmitri Mendeleev

4. Ernest Rutherford

Q.

Which of the following triads do not follow Dobereiners law of triads?

1. Li, Na, K

2. Ca, Sr, Ba

3. Be, Mg, Ca

4. Cu, Ag, Au

Q.

What is Debereiner’s law of triads? Explain with the help of one example of a Dobereiner’s triad.

Q. Which of the following statements are true regarding Döbereiner's classification of elements?

(More than one option is correct)

1. Döbereiner classified all the elements known at that time into triads.
2. Every eighth element had properties similar to that of the first element in Döbereiner's classification.
3. The mass of middle element was roughly the average of atomic masses of other two elements in the triad.
4. Elements in a triad show similar properties.

Q. Three elements A, B and C form a Döbereiner’s triad. Atomic weights of first element A and middle element C are 35 u and 79 u respectively. If the atomic number of element B is 61, then the total number of neutrons in its nucleus is (Assume atomic weight = Mass number)

1. 61
2. 63
3. 60
4. 62

Q.

If chlorine, bromine and iodine form a Dobereiner's triad and the atomic masses of chlorine and iodine are 35.5 u and 127.0 u respectively, then the atomic mass of bromine is _____.

1. 162 u

2. 91 u

3. 81 u

4. 45 u

Q. If elements A, B and C form a Dobereiner's triad, then, atomic mass of element B is the arithmetic mean of atomic masses of A and C.

1. False
2. True

Q. If Li, Na, and an unknown element X, form a Döbereiner's triad, then the atomic mass of X is ______ amu.

1. 39

Q.

(a) A, B and C are the elements of a Dobereiner's triad. If the atomic mass of A is 7 and that of C is 39, what should be the atomic mass of B?

(b) Why was Dobereiner's triad discarded?

Q. The set of do not form a Döbereiner’s triad.

1. $N\left(14\right),P\left(31\right),\mathrm{As}\left(75\right)$
2. $\mathrm{Ca}\left(40\right),\mathrm{Sr}\left(88\right),\mathrm{Ba}\left(137\right)$
3. $\mathrm{Cl}(35.5),\mathrm{Br}\left(80\right),I\left(127\right)$

Q. Which of the following belongs to the group of Doberiener's triad?

1. Calcium, strontium, and barium
2. Chlorine, bromine, and iodine
3. Hydrogen, lithium, and sodium
4. Phosphorus, vanadium and niobium

Q.

Which of the following is a Döbereiner's triad?

1. Ne, Ca, Na

2. $H_2,N_2,O_2$

3. Li, Na, K

4. Cl, Na, Ca

Q.

Explain Dobereiner’s triads.

Q. Which of the following statements are true regarding Döbereiner's classification of elements?

(More than one option is correct)

1. Döbereiner classified all the elements known at that time into triads.
2. Every eighth element had properties similar to that of the first element in Döbereiner's classification.
3. The mass of middle element was roughly the average of atomic masses of other two elements in the triad.
4. Elements in a triad show similar properties.

Q.

The three elements A, B, and C with similar properties have atomic masses X, Y, and Z respectively. The mass of Y is approximately equal to the average mass of X and Z. What is such an arrangement of elements called? Give one example of such a set of elements.