Why is the periodic table of the elements shaped the way it is?

Question

Look at it, it's not in any sensible shape. I asked one of my friends this question, and they said it is because there are spaces reserved for undiscovered elements. At this, I asked him how they know about these elements if they are undiscovered.

He didn't have an answer to this, maybe you do?

Answer 1

The periodic table is laid out as a maxtix with groups running across from left to right and periods running down from top to bottom. Read this excerpt from Wikipedia for an explanation. Also see the link to the Wikipedia article.

The layout of the periodic table demonstrates recurring ("periodic") chemical properties. Elements are listed in order of increasing atomic number (i.e. the number of protons in the atomic nucleus). Rows are arranged so that elements with similar properties fall into the same vertical columns ("groups"). According to quantum mechanical theories of electron configuration within atoms, each horizontal row ("period") in the table corresponded to the filling of a quantum shell of electrons. There are progressively longer periods further down the table, grouping the elements into s-, p-, d- and f-blocks to reflect their electron configuration.

In printed tables, each element is usually listed with its element symbol and atomic number; many versions of the table also list the element's atomic mass and other information, such as its abbreviated electron configuration, electronegativity and most common valence numbers.

As of 2006, the table contains 117 chemical elements whose discoveries have been confirmed. Ninety-two are found naturally on Earth, and the rest are synthetic elements that have been produced artificially in particle accelerators. Elements 43 (technetium) and 61 (promethium), although of lower atomic number than the naturally occurring element 92, uranium, are synthetic; elements 93 (neptunium) and 94 (plutonium) are listed with the synthetic elements, but have been found in trace amounts on earth.


[edit] Periodicity of chemical

Answer 2

It is in a very sensible shape. It's shaped that way because of the numbers of electrons required to fill various shells in atoms. It happens that 2 electrons fill the first shell, 8 fill the second, and so on.

The lanthanides and actinides are removed from the middle to save space. If you stuck them in their correct spot, the table would be about twice as wide and wouldn't fit conveniently on a piece of paper.

Answer 3

Even though the elements are undiscovered the elements still follow a perdictable path that allows us to know where elements belong even if we did not find them yet.