chemical elements periodic table

Periodic Table of Elements

Periodic Table of Chemical Elements + Free Printable Periodic Table

The periodic table of 118 chemical elements was first conceived in 1869 by Russian chemist Dmitri Mendeleev who used the periodic table to predict the properties of elements, including some before they were discovered. 2019 is the 150th anniversary of the periodic table of chemical elements and has been proclaimed by the UN and UNESCO as the “International Year of the Periodic Table of Chemical Elements”.

Periodic Table FAQs

Frequently Asked Questions About the Periodic Table

What does “Periodic” mean in the periodic table?
Elements in a period have the same number of atomic orbitals. For example, every element in the top row (the first period) has one orbital for its electrons. All of the elements in the second row (the second period) have two orbitals for their electrons.

Chemical elements are grouped into periods (rows), ordered by their atomic number, which have the same number of atomic orbitals. For example all the elements in the top row (period) has one orbital of its electrons. All the elements in the second row (second period) have two orbitals for their electrons, as so on for the other periods. The first element in each row has just one electron in its outer shell which means it is unstable and the most reactive. The last element in each row has a full shell of electrons so these elements are the least reactive and most stable. Elements which share similar properties are called congeners and (by skipping columns) are grouped together as follows:

  • 7 rows: Each row represents a period and includes chemical elements ordered by the number of protons in their nucleus.
  • 18 columns: Columns are used to group together chemical elements which share similar properties.

Why do some elements have names which do not match its symbol?
Most of the abbreviations for elements are derived from Latin. Here’s a list of chemical elements with symbols which do NOT match their names with explanations:

  • Antimony (Sb)
    The symbol Sb for Antimony is taken from Latin “stibium“, Greek “stíbi” which means “eye paint” because antimony was used in eye cosmetics.
  • Copper (Cu)
    The symbol Cu for Copper is taken from Latin “Cuprum” a contraction of “Cyprian metal” from Cyprus which was famous for copper.
  • Gold (Au)
    The symbol Au for Gold is taken from Latin “aurum” (yellow) and from “aurora” (dawn).
  • Iron (Fe)
    The symbol Fe for Iron is taken from Latin “errum” which means iron or sword.
  • Lead (Pb)
    The symbol Pb for Lead is taken from Latin “plumbum” probably derived from an earlier language than Greek.
  • Mercury (Hg)
    The symbol Hg for Mercury is taken from Greek “hydrargyros” (liquid silver or quicksilver in English) resulting in “hydrargyrum“. Alchemists believed hydrargyrum was close to gold so named it after the planet closest to the Sun, which is Mercury.
  • Potassium (K)
    The symbol K for Potassium is taken from Latin “Kalium“.
  • Silver (Ag)
    The symbol Ag for Silver is taken from Latin “argentum” probably derived from an Indo-European word for shiny metal. Argentina is the only country named after a chemical element.
  • Sodium (Na)
    The symbol Na for Sodium is taken from Latin “natrium“, Greek “nítron” and earlier Arabic “natrun“.
  • Tin (Sn)
    The symbol Sn for Silver is taken from latin “stannum” probably derived from the Indo-European word “stag” (dripping) because tin is easily melted.
  • Tungsten (W)
    The symbol W for Tungsten refers to “Wolfram” the mineral found in wolframite, from the German “wolf rahm/wolf’s foam” – the amount of tin consumed to extract Tungsten.
Chemical Element Groups & Classifications Explained

You will find chemical elements grouped, spelt and colored differently in various versions of the periodic table but the underlying principle remains the same i.e. chemical elements that share similar properties are organized in columns. The ADDucation Period Table Groups (aka Classifications) are:

  • Alkali Metals: These metals do not occur freely in nature because they react violently with water. Their usual oxidation state is +1. The 6 akali metals are Lithium, Sodium, Potassium, Rubidium, Cesium and Francium.
  • Alkaline Earth Metals: These reactive metals do not occur freely in nature and their usual oxidation state is +2. The 6 alkaline earth metals are Beryllium, Magnesium, Calcium, Strontium, Barium and Radium.
  • Transition Metals: There are 38 elements in total including Iron, Cobalt and Nickel which are the only known elements which produce magnetic fields. The valence electrons (or the electrons they use to combine with other elements) in transition metals are present in more than one shell and for this reason they often exhibit several common oxidation states.
  • Other Metals (aka basic metals, poor metals): These elements are all solid and opaque. All their valence electrons in their outer shell so, unlike transition elements, they don’t exhibit variable oxidation states. The 7 basic metals are: Aluminum, Gallium, Indium, Tin, Thallium, Lead and Bismuth.
  • Rare Earth Elements (aka inner transition metals): 30 rare earth elements divided into the Lanthanide and Actinide series, each containing 15 elements. They are all highly reactive with Halogens.
    • Lanthanides are silvery white metals which all have similar properties to Lanthanum, the first element in the series.
    • Actinides are named after Actinium, the first element in the series. Apart from Uranium and Thorium they are trans-uranium, which means synthetic or man-made, and they are created in nuclear reactors, including Plutonium, which is used in nuclear weapons.
  • Metalloids (aka semi-metals): This group of 7 elements makes up the diagonal border between metals and non-metals and they each have properties from both groups. Metals are generally ductile, malleable and conduct heat and electricity. Under certain conditions Germanium and Silicon can be conductive or non-conductive and it’s this property which makes them so useful in electronic circuitry. The other 5 metalloids are Boron, Arsenic, Antimony, Tellurium and Polonium.
  • Non-Metals: Generally poor conductors, brittle and non-reflective and, at room temperature, can exist as gases (e.g Oxygen) and solids. The 7 non-metals are Hydrogen, Carbon, Nitrogen, Oxygen, Phosphorus, Sulfur and Selenium.
  • Halogens (means “salt-former”): There are 5 Halogens which, at room temperature, exist in all three states of matter. Iodine and Astatine as solids, Bromine as a liquid and Fluorine and Chlorine as gases. All Halogens have an oxidation number of -1.
  • Noble Gases: All noble gases have an oxidation number of 0 which makes them stable and generally inert. The noble gases are Helium, Neon, Argon, Krypton, Xenon, Radon and possibly Oganesson.

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