Atomic Mass and Atomic Number Simulation
Each square on the periodic table represents an element. Within each square, there is information about that element.
Between 1829 and 1869, there were several versions of the periodic table that were proposed, but it was not until 1869 until a model of the periodic table was widely accepted. In 1869, Dmitri Mendeleev arranged his periodic table in order of increasing atomic mass. In Mendeleev's original periodic table, he left spaces because he predicted that there would be additional elements that would be discovered later on. Later on, Mendeleev found problems with his periodic table. He thought the atomic masses were wrong for some of the elements, but they were not wrong. There was something else wrong with this arrangement. As new information was discovered, such as atoms contain a unique number of protons, a new periodic table arrangement was proposed. We call this arrangement the "modern periodic table" which is arranged in order of increasing atomic number (number of protons). Due to elements being arranged by the atomic number, we now have the Periodic Law which states that if elements are arranged by increasing atomic number, there will be repeating patterns of physical and chemical properties of the elements. For example, elements have similar properties as you move down a group (column) from one period (row) to the next. Also, you can predict properties of elements based on their location on the periodic table.
- The modern periodic table now is filled in and does not have any spaces through out it, but the periodic table does have places for possible future elements. In fact, four new elements were discovered in 2016.
- When looking at the periodic table below, we see that it is very spread out, and we more commonly see the periodic table below which is more compact. The "inner transition" metals are moved to the bottom which makes this periodic table easier to work with.