AP Chemistry : History of the Periodic Table

Study concepts, example questions & explanations for AP Chemistry

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Example Questions

Example Question #1 : History Of The Periodic Table

Dmitri Mendeleev is credited as publisher of the first version of the periodic table similar to the one presently used. He found patterns in the behavior of some elements and grouped them together as such. While there were many benefits of Mendeleev's table that helped to advance our knowledge of chemistry, there are several shortcomings that it still cannot address.

The placement of hydrogen on the periodic table is somewhat misleading. Which of the following statements about hydrogen is false?

Possible Answers:

Hydrogen is an alkali metal.

The predominant isotope of hydrogen has 1 proton and no neutrons.

Hydrogen can behave as both an alkali metal and as a halogen.

Hydrogen has one valence electron.

Correct answer:

Hydrogen is an alkali metal.


Hydrogen has an atomic mass of 1.009 amu, which implies that  is the predominant isotope. Neutral hydrogen has an equal number of protons as electrons, which is 1 each. While hydrogen can behave as an alkali metal or as a halogen by losing or gaining an electron to attain a full valence shell, it does not exhibit properties of metals, which are electrically and thermally conductive. Thus the location of hydrogen on the periodic table may be misleading, since it is a nonmetal.

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