Periodic table | Definition, Elements, Groups, Charges, Trends, & Facts (2024)

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Also known as: periodic table of the elements

Written by

Linus C. Pauling Research Professor, Linus Pauling Institute of Science and Medicine, Palo Alto, California, 1973–94. Professor of Chemistry, Stanford University, California, 1969–74. Nobel Prize for Chemistry, 1954; Nobel...

Linus C. Pauling,

J.J. Lagowski Professor of Chemistry, University of Texas at Austin. Author of The Chemical Bond.

J.J. LagowskiAll

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periodic table

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In full:
periodic table of the elements
Key People:
Dmitri Mendeleev
Lothar Meyer
Paul-Émile Lecoq de Boisbaudran
Related Topics:
chemical element
atom
group
period
periodic law

See all related content →

Top Questions

What is the periodic table?

The periodic table is a tabular array of the chemical elements organized by atomic number, from the element with the lowest atomic number, hydrogen, to the element with the highest atomic number, oganesson. The atomic number of an element is the number of protons in the nucleus of an atom of that element. Hydrogen has 1 proton, and oganesson has 118.

What do periodic table groups have in common?

The groups of the periodic table are displayed as vertical columns numbered from 1 to 18. The elements in a group have very similar chemical properties, which arise from the number of valence electrons present—that is, the number of electrons in the outermost shell of an atom.

Where does the periodic table come from?

The arrangement of the elements in the periodic table comes from the electronic configuration of the elements.Because of the Pauli exclusion principle, no more than two electrons can fill the same orbital.The first row of the periodic table consists of just two elements, hydrogen and helium. As atoms have more electrons, they have more orbits available to fill, and thus the rows contain more elements farther down in the table.

Why does the periodic table split?

The periodic table has two rows at the bottom that are usually split out from the main body of the table. These rows contain elements in the lanthanoid and actinoid series, usually from 57 to 71 (lanthanum to lutetium) and 89 to 103 (actinium to lawrencium), respectively. There is no scientific reason for this. It is merely done to make the table more compact.

periodic table, in chemistry, the organized array of all the chemical elements in order of increasing atomic number—i.e., the total number of protons in the atomic nucleus. When the chemical elements are thus arranged, there is a recurring pattern called the “periodic law” in their properties, in which elements in the same column (group) have similar properties. The initial discovery, which was made by Dmitry I. Mendeleev in the mid-19th century, has been of inestimable value in the development of chemistry.

It was not actually recognized until the second decade of the 20th century that the order of elements in the periodic system is that of their atomic numbers, the integers of which are equal to the positive electrical charges of the atomic nuclei expressed in electronic units. In subsequent years great progress was made in explaining the periodic law in terms of the electronic structure of atoms and molecules. This clarification has increased the value of the law, which is used as much today as it was at the beginning of the 20th century, when it expressed the only known relationship among the elements.

History of the periodic law

The early years of the 19th century witnessed a rapid development in analytical chemistry—the art of distinguishing different chemical substances—and the consequent building up of a vast body of knowledge of the chemical and physical properties of both elements and compounds. This rapid expansion of chemical knowledge soon necessitated classification, for on the classification of chemical knowledge are based not only the systematized literature of chemistry but also the laboratory arts by which chemistry is passed on as a living science from one generation of chemists to another. Relationships were discerned more readily among the compounds than among the elements; it thus occurred that the classification of elements lagged many years behind that of compounds. In fact, no general agreement had been reached among chemists as to the classification of elements for nearly half a century after the systems of classification of compounds had become established in general use.

Britannica Quiz118 Names and Symbols of the Periodic Table Quiz

J.W. Döbereiner in 1817 showed that the combining weight, meaning atomic weight, of strontium lies midway between those of calcium and barium, and some years later he showed that other such “triads” exist (chlorine, bromine, and iodine [halogens] and lithium, sodium, and potassium [alkali metals]). J.-B.-A. Dumas, L. Gmelin, E. Lenssen, Max von Pettenkofer, and J.P. Cooke expanded Döbereiner’s suggestions between 1827 and 1858 by showing that similar relationships extended further than the triads of elements, fluorine being added to the halogens and magnesium to the alkaline-earth metals, while oxygen, sulfur, selenium, and tellurium were classed as one family and nitrogen, phosphorus, arsenic, antimony, and bismuth as another family of elements.

Attempts were later made to show that the atomic weights of the elements could be expressed by an arithmetic function, and in 1862 A.-E.-B. de Chancourtois proposed a classification of the elements based on the new values of atomic weights given by Stanislao Cannizzaro’s system of 1858. De Chancourtois plotted the atomic weights on the surface of a cylinder with a circumference of 16 units, corresponding to the approximate atomic weight of oxygen. The resulting helical curve brought closely related elements onto corresponding points above or below one another on the cylinder, and he suggested in consequence that “the properties of the elements are the properties of numbers,” a remarkable prediction in the light of modern knowledge.

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Classification of the elements

In 1864, J.A.R. Newlands proposed classifying the elements in the order of increasing atomic weights, the elements being assigned ordinal numbers from unity upward and divided into seven groups having properties closely related to the first seven of the elements then known: hydrogen, lithium, beryllium, boron, carbon, nitrogen, and oxygen. This relationship was termed the law of octaves, by analogy with the seven intervals of the musical scale.

Then in 1869, as a result of an extensive correlation of the properties and the atomic weights of the elements, with special attention to valency (that is, the number of single bonds the element can form), Mendeleev proposed the periodic law, by which “the elements arranged according to the magnitude of atomic weights show a periodic change of properties.” Lothar Meyer had independently reached a similar conclusion, published after the appearance of Mendeleev’s paper.

Periodic table | Definition, Elements, Groups, Charges, Trends, & Facts (2024)

FAQs

What are the groups and their charges on the periodic table? ›

You can use periodic table trends to predict the most common element charges. Group I (alkali metals) carry a +1 charge, Group II (alkaline earth metals) carry a +2, Group VII (halogens) carry -1, and Group VIII (noble gases) carry a 0 charge. Metal ions may have other charges or oxidation states.

What is a good definition for the periodic table? ›

periodic table. noun. : an arrangement of chemical elements in order of atomic number that groups elements with common characteristics in the same area of the table.

What are the 7 periodic properties? ›

Periodic Properties of the Elements
  • Atomic Radius.
  • Ionization Energy (ionization potential)
  • Electron Affinity.
  • Electronegativity.
  • Metallic Character.
  • Other Trends.
  • Redox Potentials. Oxidation Potential. Reduction Potential.
  • Uses in knowing the Periodic Properties of Elements.
Jun 30, 2023

What is the periodic table for 5th grade? ›

The periodic table of the elements is a visual way that chemists have developed to organize the elements of the universe. With this method elements are grouped next to other elements that are similar.

What is the charge of the elements? ›

The charge of an element is the # of protons - # of electrons. For example, a chlorine atom that gains an electron will have a charge of -1 because 17 - 18 = -1 (17 protons, 18 electrons). You can calculate the charge of any element using this formula.

What are the 8 main groups of the periodic table? ›

Name of the eight groups in the periodic table:
  • Alkali metals.
  • Alkaline earth metals.
  • Rare earth metals.
  • Crystallogens.
  • Pnictogens.
  • Chalcogens.
  • Halogens.
  • Noble gases.

What are the main five elements? ›

Feedback? According to the five elements theory, everything in nature is made up of five elements: Earth, Water, Fire, Air, and Space.

What is the most important thing on the periodic table? ›

Hydrogen is the most abundant element in the universe, and as its atomic number suggests, it's pretty important. There's hydrogen in the air you breathe, the water you drink, and the tech on your desk. Gaseous hydrogen is used to manufacture all kinds of electronics (like silicon computer chips).

How to understand periodic table easily? ›

The elements are arranged in order of increasing atomic number across a period from left to right, so each element has one more proton in its nucleus compared to the preceding one. The properties also change across a period – that's why metals are on the left, and non-metals on the right.

What is the purpose of the zigzag line on the periodic table? ›

In the Modern Periodic Table, a zig-zag line separates metals from non-metals. Metals are founded on the left side of the staircase whereas non-metals are founded on the right side of the staircase. Metalloids are directly touching the staircase and can be also called Semimetals.

How do periodic trends work? ›

Trend-wise, as one moves from left to right across a period in the modern periodic table, the ionization energy increases as the nuclear charge increases and the atomic size decreases. The decrease in the atomic size results in a more potent force of attraction between the electrons and the nucleus.

What are the elements of trends? ›

The three fundamental elements – basic needs, external change and innovations – will help you understand consumer trends. But sensing where and how these come together to form new levels of customer expectation will help you act on trends.

Which element is the rarest on Earth? ›

Astatine is a chemical element; it has symbol At and atomic number 85. It is the rarest naturally occurring element in the Earth's crust, occurring only as the decay product of various heavier elements. All of astatine's isotopes are short-lived; the most stable is astatine-210, with a half-life of 8.1 hours.

What is the lightest element? ›

Hydrogen is the lightest element and exhibits the simplest atomic structure. In addition, it is the most abundant element in the universe and can form bonds to nearly every element, such as s- and p-block elements.

What charge does group 4 have? ›

If an element in 4A loses all four valence electrons it gets a +4 charge, also known as a +4 oxidation state. Generally, the elements at the top of this group have the +4 oxidation state while the elements at the bottom have the +2 state, but we'll take a closer look at this when we examine each element.

What charge does group 2 have? ›

Thus, the group 2 metals tend to have a +2 charge.

What charge is group 3? ›

The chemistry of the group 3 elements is typical for early transition metals: they all essentially have only the group oxidation state of +3 as a major one, and like the preceding main-group metals are quite electropositive and have a less rich coordination chemistry.

What are groups of atoms with a charge? ›

A group of atoms carrying a charge is known as a polyatomic ion. These are also known as molecular ions. Polyatomic ions are covalently bonded groups of atoms. Have a positive or negative charge caused by the formation of an ionic bond with another ion.

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