"The periodic table, also known as the periodic table of the elements, arranges the chemical elements into rows ("periods") and columns ("groups")."
Presents the periodic table as a systematic arrangement of elements according to their atomic number and electron configuration, and highlights its main features (e.g. periods, groups, blocks).
Atoms: The basic unit of matter that makes up all elements in the periodic table.
Protons: The positively charged particles found in the nucleus of an atom.
Neutrons: The particles found in the nucleus of an atom that have no charge.
Electrons: The negatively charged particles found outside the nucleus of an atom, orbiting around the nucleus in energy levels.
Isotopes: Atoms of the same element with different numbers of neutrons.
Atomic Number: The number of protons in the nucleus of an atom, which determines the element.
Mass Number: The sum of the number of protons and neutrons in an atom.
Valence Electrons: The electrons found in the outermost energy level of an atom which are involved in chemical bonding.
Periodic Table: A chart of the elements arranged in order of their atomic number into rows and columns based on similarities in chemical behavior.
Groups/Families: Vertical columns in the periodic table that share similar chemical properties.
Periods: Horizontal rows of the periodic table that indicate the number of energy levels an atom has.
Metals: Elements that are good conductors of heat and electricity, shiny, and malleable.
Nonmetals: Elements that are poor conductors of heat and electricity, dull, and brittle.
Metalloids: Elements that have properties of both metals and nonmetals.
Alkali Metals: The elements in Group 1 of the periodic table that are highly reactive and easily lose one electron to form a +1 ion.
Alkaline Earth Metals: The elements in Group 2 of the periodic table that are less reactive than the alkali metals but still have a strong tendency to lose two electrons to form a +2 ion.
Transition Metals: The elements in Groups 3-12 of the periodic table that have variable oxidation states and strong metallic properties.
Halogens: The elements in Group 17 of the periodic table that are highly reactive nonmetals and readily gain one electron to form a -1 ion.
Noble Gases: The elements in Group 18 of the periodic table that are chemically inert and do not readily form compounds due to their stable electronic configuration.
Mendeleev's Periodic Table: Developed by Dmitri Mendeleev in 1869, this was the first periodic table designed to show the relationships between elements based on their chemical and physical properties.
Modern Periodic Table: Based on the electronic configuration of elements, the modern periodic table arranges the elements in order of increasing atomic number.
Long Form Periodic Table: An extension of the modern periodic table, this table includes all 118 known elements.
Circular Periodic Table: In this table, the elements are arranged in a circular pattern, with the elements in the center being the most metallic and the elements on the outside being the most non-metallic.
Spiral Periodic Table: This table arranges elements in a spiral shape, with the innermost elements being the most metallic and the outermost elements being the most non-metallic.
3D Periodic Table: This table shows the elements in a three-dimensional model, with the elements arranged based on their electron shell configuration.
Mendeleev's Predictive Periodic Table: This version of Mendeleev's periodic table includes gaps or "missing elements" to predict the discovery of new elements.
Janet's Periodic Table: Based on quantum mechanics, this table arranges elements in a left-to-right and top-to-bottom manner, with the elements in the diagonal being the most metallic.
Zigzag or "Step" Periodic Table: In this table, the elements are arranged in a zigzag pattern, with the metalloids forming a step between metals and non-metals.
Left Step or "Madelung" Periodic Table: This table arranges elements based on the Madelung rule, which dictates the order in which subshells are filled with electrons.
Flatland Periodic Table: Designed by Jerome Lettvin, this table arranges the elements in a two-dimensional layout based on the concept of geometric symmetry.
Chemical Abstracts Service (CAS) Systematic Table: Arranges elements in order of their atomic number, and uses a unique identifier for each element based on its electronic configuration.
Janet's Left Step Periodic Table: A modification of Janet's periodic table, this version includes a left step to separate metals and non-metals.
Electrical Periodic Table: Based on the conductivity of each element, with metals on the left side and non-metals on the right.
Primo Levi's "Carbon-12" Table: Designed to illustrate the fundamental importance of carbon in the biological world, this table arranges elements according to their ability to bond with carbon.
Rayner-Canham Periodic Table: Arranges elements in four blocks based on their electron configuration, and distinguishes between "large" and "small" elements.
Rare Earth Periodic Table: Separates the rare earth elements from the rest of the periodic table, which can be useful for studying their unique chemical and physical properties.
Scerri's Periodic Table: Designed to emphasize the importance of valence electrons in determining an element's chemical properties, this table arranges elements in four groupings based on their electron configuration.
"It is a depiction of the periodic law, which says that when the elements are arranged in order of their atomic numbers an approximate recurrence of their properties is evident."
"The table is divided into four roughly rectangular areas called blocks."
"Elements in the same group tend to show similar chemical characteristics."
"Metallic character increases going down a group and decreases from left to right across a period."
"Nonmetallic character increases going from the bottom left of the periodic table to the top right."
"The first periodic table to become generally accepted was that of the Russian chemist Dmitri Mendeleev in 1869."
"He formulated the periodic law as a dependence of chemical properties on atomic mass."
"Mendeleev successfully used the periodic law to predict some properties of some of the missing elements."
"The periodic law was recognized as a fundamental discovery in the late 19th century."
"It was explained early in the 20th century, with the discovery of atomic numbers and associated pioneering work in quantum mechanics both ideas serving to illuminate the internal structure of the atom."
"A recognisably modern form of the table was reached in 1945 with Glenn T. Seaborg's discovery that the actinides were in fact f-block rather than d-block elements."
"The periodic table and law are now a central and indispensable part of modern chemistry."
"The periodic table continues to evolve with the progress of science."
"Today, while all the first 118 elements are known, thereby completing the first seven rows of the table..."
"...chemical characterisation is still needed for the heaviest elements to confirm that their properties match their positions."
"It is not yet known how far the table will go beyond these seven rows..."
"Some scientific discussion also continues regarding whether some elements are correctly positioned in today's table."
"Many alternative representations of the periodic law exist..."
"...and there is some discussion as to whether there is an optimal form of the periodic table."