Periodic Table Groups and Periods (2024)

This entry was posted on June 23, 2021 by Anne Helmenstine (updated on February 1, 2023)

Groups and periods organize elements on the periodic table of the elements. A group is a vertical column down the periodic table, while a period is a horizontal row across the table. Both groups and periods reflect the organization of electrons in atoms. Element atomic number increases as you move down a group from top to bottom or across a period from left to right.

  • An element group is a vertical column on the periodic table. Atoms in a group share the same number of valence electrons. There are 18 element groups.
  • An element period is a horizontal row on the periodic table. Atoms in a period have the same number of electron shells. There are 7 element periods.

Element Groups

Elements within the same group share the same number of valence electrons. The number of valence electrons depends on the octet rule. For example, elements in group 1 have 1 valence electron, elements in groups 3-12 have a variable number of valence electrons, and elements in group 17 have 7 valence electrons. The lanthanides and actinides, located below the main table, all fit within group 3.

There are 18 element groups. Elements in the same group share common chemical and physical properties. For example, the group 1 elements are all soft, reactive metals. The group 17 elements are highly reactive, colorful nonmetals.

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IUPAC NameCommon NameFamilyOld IUPACCASnotes
Group 1alkali metalslithium familyIAIAsometimes excludes hydrogen
Group 2alkaline earth metalsberyllium familyIIAIIA
Group 3transition metalsscandium familyIIIAIIIB
Group 4transition metalstitanium familyIVAIVB
Group 5transition metalsvanadium familyVAVB
Group 6transition metalschromium familyVIAVIB
Group 7transition metalsmanganese familyVIIAVIIB
Group 8transition metalsiron familyVIIIVIIIB
Group 9transition metalscobalt familyVIIIVIIIB
Group 10transition metalsnickel familyVIIIVIIIB
Group 11coinage metalscopper familyIBIB
Group 12volatile metalszinc familyIIBIIB
Group 13icoasagensboron familyIIIBIIIA
Group 14tetrels, crystallogenscarbon familyIVBIVAtetrels from the Greektetrafor four
Group 15pentels, pnictogensnitrogen familyVBVApentels from the Greekpentafor five
Group 16chalcogensoxygen familyVIBVIA
Group 17halogensfluorine familyVIIBVIIA
Group 18noble gases, aerogenshelium family or neon familyGroup 0VIIIA

Alternate Group Classification System

Sometimes chemists classify element groups according to shared properties, which do not strictly adhere to individual columns. These groups go by the names alkali metals, alkaline earth metals, transition metals, basic metals, nonmetals, halogens, noble gases, lanthanides, and actinides. Under this system, hydrogen is a nonmetal. The nonmetals, halogens, and noble gases are all types of nonmetals. The metalloids have properties intermediate between metals and nonmetals. The alkali metals, alkaline earths, lanthanides, actinides, transition metals, and basic metals are all groups of metals.

Element Periods

Elements within a period share the same number of electron shells and the same highest unexcited electron energy level. Elements within a period display periodic table trends, moving from left to right, involving atomic and ionic radius, electronegativity, There are seven element periods. Some periods contain more elements than others because the number of included elements depends on the number of electrons allowed in an energy sublevel. Note that the lanthanides are within period 6 and the actinides are in period 7.

  • Period 1: H, He (does not follow the octet rule)
  • Period 2: Li, Be, B, C, N, O, F, Ne (involves s and p orbitals)
  • Period 3: Na, Mg, Al, Si, P, S, Cl, Ar (all have at least 1 stable isotope)
  • Period 4: K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Br, Kr (first period with d-block elements)
  • Period 5: Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sn, Te, I, Xe (same number of elements as period 4, same general structure, and includes the first exclusively radioactive element, Tc)
  • Period 6: Cs, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pb, Bi, Po, At, Rn (first period with f-block elements)
  • Period 7: Fr, Ra, Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No, Lr, Rd, Db, Sg, Bh, Hs, Mt, Ds, Rg, Cn, Nh, Fl, Mc, Lv, Ts, Og (all elements are radioactive; contains heaviest natural elements and many synthesized elements)


  • Fluck, E. (1988).New Notations in the Periodic Table”.Pure Appl. Chem.IUPAC.60(3): 431–436.doi:10.1351/pac198860030431
  • Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
  • Scerri, E. R. (2007). The periodic table, its story and its significance. Oxford University Press. ISBN 978-0-19-530573-9.

Related Posts

Periodic Table Groups and Periods (2024)


Periodic Table Groups and Periods? ›

Groups and periods are two ways of categorizing elements in the periodic table. Periods are horizontal rows (across) the periodic table, while groups are vertical columns (down) the table. Atomic number increases as you move down a group or across a period.

What are the 7 periods in periodic table? ›

There are 7 periods in the periodic table. These are numbered as 1, 2, 3, 4, 5, 6 and 7 from top to bottom. The 1st period consists of only two elements – Hydrogen and Helium.

What are the 7 groups of the periodic table? ›

Different groups are present in the periodic table:
  • The Alkali Metals.
  • The Alkaline Earth Metals.
  • The Transition Metals.
  • The Non-metals.
  • The Halogens.
  • The Noble Gases.
  • The Rare Earth Elements.

What are the 18 groups in the periodic table? ›

Groups are numbered 1–18 from left to right. The elements in group 1 are known as the alkali metals; those in group 2 are the alkaline earth metals; those in 15 are the pnictogens; those in 16 are the chalcogens; those in 17 are the halogens; and those in 18 are the noble gases.

How do you know the group and period of an element? ›

The number of shells is equal to its period number and the number of valence electrons tells us about its group. Let us take Oxygen for example. Its electronic configuration is 2, 6. It has two shells and 6 valence electrons.

Are there 18 groups and 7 periods in the periodic table? ›

The given statement is absolutely correct. there are 7 periods and 18 groups in the modern periodic table.

What are 7 periods and 18 groups? ›

The modern periodic table is the present form of the periodic table in which the arrangement of elements is in the increasing order of their atomic numbers. There are 18 vertical columns or groups and 7 horizontal rows or periods in the modern periodic table.

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 9 main groups on the periodic table? ›

  • Group 1: alkali metals, or lithium family.
  • Group 2: alkaline earth metals, or beryllium family.
  • Group 3: the scandium family.
  • Group 4: the titanium family.
  • Group 5: the vanadium family.
  • Group 6: the chromium family.
  • Group 7: the manganese family.
  • Group 8: the iron family.

What is group 7 called? ›

The Group 7 elements are also known as the halogens. The three common Group 7 elements are chlorine, bromine and iodine. The word 'halogen' means 'salt former'.

What is group 13 called? ›

Group 13 is known as the Boron family.

What is group 4 called? ›

Group 4 is the second group of transition metals in the periodic table. It contains the four elements titanium (Ti), zirconium (Zr), hafnium (Hf), and rutherfordium (Rf). The group is also called the titanium group or titanium family after its lightest member.

What is group 6 called? ›

They have six elements which are Oxygen , Sulfur , Selenium , Tellurium , Polonium , and Livermorium . These elements are known as Chalcogens and are also known as the Oxygen family. Chalcogen is derived from the Greek word Chalco, which means"ore" and gen means “formation”.

How do you distinguish between a group and a period on the periodic table? ›

What is the difference between a group and a period in the periodic table? A group is a vertical column on the periodic table and a period is a horizontal row on the periodic table.

How do you read groups and periods on the periodic table? ›

Groups: The vertical column of the periodic table that signifies the number of valence electrons in an element. Periods: The horizontal rows in the periodic table that signify the number of electron shells in an element. Families: Elements that have the same number of valence electrons and therefore similar properties.

What group is oxygen in? ›

The oxygen family, also called the chalcogens, consists of the elements found in Group 16 of the periodic table and is considered among the main group elements. It consists of the elements oxygen, sulfur, selenium, tellurium and polonium.

What are the period 7 elements often called? ›

Period 7 Elements: The Actinides.

What is 7 of the periodic table? ›

Nitrogen - Element information, properties and uses | Periodic Table.

How do you remember the 7th period of the periodic table? ›

It includes Actinium (Ac), Rutherfordium (Rf), Dubnium (Db), Seaborgium (Sg), Bohrium (Bh), Hassium (Hs), Meitnerium (Mt), and Darmstadtium (Ds). Mnemonic for Period 7: Ak(c)ele R(f) D(b) S(g)harma ki B(h)ook mein H(s)ain Maths ke Difficult sawaal. Read as: Akele R D Sharma ki Book mein Hain Maths ke Difficult sawaal.

Why is the 7th period incomplete? ›

7th period is considered as an incomplete period even though it has 32 elements. Because it consists of elements whose properties have not been studied properly yet.

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