Question

1. choose the best answer.

what law revealed that the math did not work for all groups of elements, like the halogens?
law of triads
periodic law
mendeleevs law
law of octaves

1. choose the best answer.

which of these element groups includes many metals like copper, silver, and gold?
transition
alkali
noble gases
alkaline earth

Explanation:

• For question 15: The law of triads was proposed by Johann Wolfgang Döbereiner. It stated that when elements are arranged in groups of three (triads) in order of increasing atomic mass, the atomic mass of the middle element is approximately the average of the atomic masses of the other two elements. However, this law did not work well for all groups of elements like the halogens. The periodic law (Mendeleev's law is also a form of periodic law) and the law of octaves (which had its own limitations but not in the same way as the law of triads for this specific context) are different.
• For question 16: Transition metals are a group of elements in the d - block of the periodic table. They have properties such as variable oxidation states, the ability to form colored compounds, and many of them are good conductors of heat and electricity. Copper (Cu), silver (Ag), and gold (Au) are all transition metals. Alkali metals (e.g., Li, Na, K) are in group 1, noble gases (e.g., He, Ne, Ar) are in group 18, and alkaline earth metals (e.g., Be, Mg, Ca) are in group 2, and none of these groups include copper, silver, and gold.

Answer:

1. law of triads
2. transition