Science, Tech, Math › Science Why Is the Periodic Table Important? Share Flipboard Email Print Insomnela / Getty Images Science Chemistry Periodic Table Basics Chemical Laws Molecules Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated February 03, 2020 The periodic table has gone through many changes since Dmitri Mendeleev drew up its original design in 1869, yet both the first table and the modern periodic table are important for the same reason: The periodic table organizes elements according to similar properties so you can tell the characteristics of an element just by looking at its location on the table. Before all naturally occurring elements were discovered, the periodic table was used to predict the chemical and physical properties of elements in the gaps on the table. Today, the table can be used to predict properties of elements yet to be discovered, although these new elements are all highly radioactive and break down into more familiar elements almost instantly. Now, the table is useful for modern students and scientists because it helps predict the types of chemical reactions that a particular element is likely to participate in. Rather than memorizing facts and figures for each element, students and scientists need only glance at the table to learn much about the reactivity of an element, whether it is likely to conduct electricity, whether it is hard or soft, and many other characteristics. Elements in the same column as one other are known as groups and they share similar properties. For example, the elements in the first column (the alkali metals) are all metals that usually carry a 1+ charge in reactions, react vigorously with water, and combine readily with nonmetals. Elements in the same row as one other are known as periods and they share the same highest unexcited electron energy level. Another useful feature of the periodic table is that most tables provide all the information you need to balance chemical reactions at a glance. The table tells each element's atomic number and usually its atomic weight. The typical charge of an element is indicated by its group. Trends or Periodicity The periodic table is organized according to trends in element properties. As you move from left to right across a row of elements, the atomic radius (the size of an element's atoms) decreases, ionization energy (the energy required to remove an electron from an atom) increases, electron affinity (the amount of energy released when an atom forms a negative ion) generally increases, and electronegativity (an atom's tendency to attract a pair of electrons) increases. As you move from top to bottom down a column of elements, the atomic radius increases, ionization energy decreases, electron affinity usually decreases, and electronegativity decreases. Summary To summarize, the periodic table is important because it is organized to provide a great deal of information about elements and how they relate to one another in one easy-to-use reference. The table can be used to predict the properties of elements, even those that have not yet been discovered.Columns (groups) and rows (periods) indicate elements that share similar characteristics.The table makes trends in element properties apparent and easy to understand.The table provides important information used to balance chemical equations.