Answer Unlocked: Express the Group Number as an Integer.


This element has 5 electrons in its valence shell. It means it must be having outermost configuration as ns2 np3 which makes a total of 5 valence electrons. This element belongs to nitrogen family. Therefore the group number of this element is 15.

Group is vertical column while period is horizontal column. 

Answer Unlocked: Express The Group Number As An Integer.Answer Unlocked:

The valence shell refers to the outermost electron shell of an atom. It is the highest energy level in an atom and contains the electrons involved in chemical bonding and interactions with other atoms.

The number of electrons in the valence shell determines the chemical properties of an atom and how it interacts with other atoms to form chemical bonds. The valence electrons are responsible for the formation of chemical bonds, including covalent bonds (sharing of electrons) or ionic bonds (transfer of electrons).

The valence shell is significant because it determines the atom’s ability to gain, lose, or share electrons in order to achieve a stable electron configuration, typically by filling or emptying the valence shell. Atoms tend to be more stable and chemically inert when their valence shell is full, following the octet rule for many elements.

Group Number

The group number refers to the position of an element in the periodic table. It is also known as the “family” or “group” of elements. The group number indicates the number of valence electrons an element has in its outermost shell or energy level.

The modern periodic table is organized into numbered groups or columns. There are 18 groups in total, labeled from 1 to 18. Each group contains elements with similar chemical properties because they have the same number of valence electrons.

  • Group 1 (Alkali Metals): Elements in this group have one valence electron and are highly reactive. They are soft metals and are known for their ability to form strong ionic bonds.
  • Group 2 (Alkaline Earth Metals): Elements in this group have two valence electrons and are also quite reactive, but less so than alkali metals. They are also metals and have higher melting and boiling points than alkali metals.
  • Group 17 (Halogens): Elements in this group have seven valence electrons and are highly reactive nonmetals. They easily form compounds with elements from other groups, especially alkali metals.
  • Group 18 (Noble Gases): Elements in this group have a full valence shell of electrons (usually eight), making them chemically stable and nonreactive. They are called noble gases and are known for their low reactivity.

How to Calculate Group Number?

The group number of an element can be determined based on its electron configuration. To calculate the group number, you need to identify the number of valence electrons, which are the electrons in the outermost energy level (valence shell) of the atom.

  • Identify the element you want to determine the group number for.
  • Find the electron configuration of the element. The electron configuration describes how the electrons are distributed in different energy levels or shells around the nucleus of the atom. For example, the electron configuration of oxygen (O) is 1s^2 2s^2 2p^4.
  • Determine the highest principal quantum number (n) in the electron configuration. The principal quantum number indicates the energy level or shell of the outermost electrons. In the case of oxygen, the highest n value is 2, indicating that the valence electrons are in the second energy level.
  • Identify the number of valence electrons. The valence electrons are the electrons in the outermost energy level (valence shell). For elements in the s- and p-blocks of the periodic table (groups 1-2 and 13-18), the number of valence electrons corresponds to the group number. For example, oxygen has six valence electrons (2s^2 2p^4 configuration), so its group number is 6.

It’s important to note that for transition metals (groups 3-12), the determination of the group number is more complex due to the involvement of inner electron shells in bonding. In such cases, the group number may not directly correspond to the number of valence electrons.

By considering the electron configuration and identifying the valence electrons, you can calculate the group number of an element in most cases.

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