A covalent bond is a chemical bond where electron pairs are shared between two atoms. For the octet rule to be satisfied the compound can be formed by the sharing of the electrons or the transfer of the electrons. Jan 20, 2017 the octet rule in chemistry is a chemical rule that explains the rules of atoms, electrons and their forms. The octet rule is followed in so many compounds it is a useful guide. Nov 26, 2017 the octet rule is a general rule that is used to describe chemical bonding and draw lewis structures. Octet, in chemistry, the eightelectron arrangement in the outer electron shell of the noblegas atoms. Valence bond theory lewis dot structures, the octet. The octet rule is a general rule that is used to describe chemical bonding and draw lewis structures. A variablelength sequence of octets, as in abstract syntax notation one asn. Dec 27, 20 the octet rule states that atoms can combine either by transferring or by sharing their valence electrons to attain an octet of electrons in their valence shell. When atoms have fewer than eight electrons, they tend to react and form more stable compounds. Atoms will lose, gain or share electrons to achieve the electron configuration of. Thus it loses the two electrons in its valence shell third energy level and attains an octet in its second energy level by forming magnesium ion.
It governs the way atoms are formed, and how they interact with other atoms to form molecules. Many elements are not chemically stable by themselves. According to this useful rule of thumb, many, if not most, atoms will try to lose or gain electrons to have a total of eight in the external shell. The octet rule refers to the tendency of atoms to prefer to have eight electrons in the valence shell outer orbital. An atom will bond with another in order to satisfy the octet rule. According to the bohr model, an atom consists of a nucleus of protons and neutrons orbited by. Only the s and p electrons are involved in the octet rule, making it useful for. The rule is especially applicable to carbon, nitrogen, oxygen, and the halogens, but also to metals such as sodium or magnesium. In a chemical formula, the octet rule strongly governs the number of atoms. Basically, it states that every atom wants to have eight valence electrons in its outermost electron shell. Hydrogen is excluded because it can hold a maximum of 2 electrons in its valence shell.
As the octet rule requires eight electrons around each atom, a molecule with an odd number of electrons must disobey the octet rule. Electrons are shared between the atoms in such a way that they each attain the octet or duplet state. The octet rule dictates particular electron placement on the orbitals of the atoms nucleus. One limitation of the octet rule is that it cannot be applied to the nonmetals after silicon in the periodic table. The octet rule dictates that an atom is most stable when its valence shell is filled with eight electrons. However, it applies to carbon, nitrogen, oxygen, the halogens, and most metals, especially the alkali metals and alkaline earths. The octet rule also applies when covalent bonds are formed. In general, the elements that obey this rule include the sblock elements and the pblock elements with the exception of hydrogen, helium, and lithium. Feb 11, 2020 this reminds us that the octet rule is not a law of nature, but rather an empirical rule that is useful within certain limits. Search inside this book for more research materials.
The octet rule states that elements gain or lose electrons to attain an electron configuration of the nearest noble gas. A group of eight singers or eight instrumentalists. Lewis structure, also called electrondot structure, is a structural formula in which electrons are represented by dots. According to octet rule, atoms gain, lose or share valence electrons to attain eight valence electrons or complete their octet. The octet rule is a general rule of thumb that applies to most atoms. Often the atoms comprising a complex molecule can be arranged in several ways and still satisfy the octet rule for each atom. The octet rule also fails in many situations involving covalent bonding. How does the octet rule explain the formation of a. With an odd number of electrons, at least one atom in the molecule will have to violate the octet rule. Learning the octet rule is an important part of understanding basic chemistry. Exceptions to the octet rule boundless chemistry lumen learning. Learn vocabulary, terms, and more with flashcards, games, and other study tools. While typically highly unstable, and therefore highly reactive, some free.
These elements can expand their octet and have more than eight valence electrons around the central atom. The molecules of the halogens, oxygen, nitrogen, and carbon are known to obey the octet rule. This gives the atom a valence shell resembling that of a noble gas. When discussing the octet rule, we do not consider d or f electrons. The rule states that main group elements form bonds in a manner that results in each atom. The basic formula of the octet rule is straight forward. In this model, the structure obeys the octet rule and the charge distribution is in agreement with the electronegativity of the atoms. The octet rule is so simple and useful in introducing the basic concepts of bonding that you might assume that it is always obeyed. The octet rule says that many elements share an octet 8 of electrons in their valence outermost electron shell when they form compounds. The octet rule is a simple chemical theory that states that atoms tend to combine in such a way that they each have eight electrons in their valence shells, similar to the electronic configuration of a noble gas. A formal definition of the octet rule, from northwestern university, states that atoms will lose, gain or share electrons to achieve the electron configuration of the nearest noble gas 8 valence electrons except for he with 2. The element attaining octet configuration has completely filled outermost s and p orbitals. Octet rule detailed explanation with examples, exceptions.
A train of heavy wagons rumbled north on the winnipeg trail, drawn by octets of oxen garrison keillor. And so nitrogen is also going to follow the octet rule when youre drawing your dot structures. Exceptions to the octet rule h 3po 4 phosphoric acid under no circumstances can the second row elements be surrounded by more than eight electrons. According to the bohr model, an atom consists of a nucleus of protons and neutrons orbited by a number of electrons. A rule in electron configuration that focuses on the tendency of atoms to. All other elements attempt to gain, lose, or share electrons to achieve a noble gas configuration. Oct 23, 2015 an easy way to understand the octet rule. Octetrule dictionary definition octetrule defined yourdictionary. Examples of stable oddelectron molecules are no, no 2. Octet rule article about octet rule by the free dictionary. The octet rule is only applicable to the main group elements.
Octet rule detailed explanation with examples, exceptions byjus. The octet rule states that atoms gain or lose electrons to attain an outer shell electron configuration nearest that of a noble gas. The attractive force between atoms is informally measured with this rule. Give a rationale for the octet rule and the duet rule for h. It defines the propensity of elements belonging to the main groups in the periodic table, to react with each other to form compounds and become stable. H, where the electrons represented by the two dots come from the 2s orbital of lithium and the 1s orbital of hydrogen. For example, bf3 will readily bind a fluoride anion to form the bf4 anion, in which boron follows the octet rule. Molecules with unpaired electrons are termed free radicals. Apr, 2020 the octet rule is a basic chemistry rule that allows easy memorization of certain atomic properties. In chemistry, the octet rule explains how atoms of different elements combine to form molecules. Basically, it may state that every atom might want to have eight valence electrons in its outermost electron shell background. The octet rule is a chemical rule of thumb that reflects the observation that elements tend to bond in such a way that each atom has eight electrons in its valence. Octet rule simple english wikipedia, the free encyclopedia.
A set of eight valence electrons in an atom or ion, forming a. The octet rule might be a general rule of thumb that may apply to most atoms. It was named from gilbert newton lewis, who introduced it in 1916. Biology glossary search by atoms will lose, gain or share electrons to achieve the electron configuration of the nearest noble gas 8 valence electrons except for he with 2. The octet rule states that a compound is only stable if its electronic configuration is such that there is a presence of 8 e. The octet rule is a chemical rule of thumb that reflects the observation that elements tend to bond in such a way that each atom has eight electrons in its valence shell, giving it the same electronic configuration as a noble gas. While typically highly unstable, and therefore highly reactive, some free radicals exhibit stability of days, months, or even years.
Information and translations of octet rule in the most comprehensive dictionary definitions resource on the web. Everything within our planet is made up of atoms, and it is interesting to understand how they work. The octet rule refers to the tendency of atoms to prefer to have eight electrons in the valence shell. A composition for eight voices or eight instruments. The octet rule in chemistry is the principle that bonded atoms share their eight outer electrons. Nov 02, 2018 the octet rule states that atoms gain or lose electrons to attain an outer shell electron configuration nearest that of a noble gas.
Basically, it may state that every atom might want to have eight valence electrons in its outermost electron shell. Exceptions to the octet rule fall into one of three categories. Scope of the octet rule for the lightest atoms the octet rule must be modified, since the noblegas configuration will be that of helium, which is simply s2 rather than s2p6. In simple terms, molecules are more stable when the outer shells of their constituent atoms are empty, full, or have a multiple of 8. Here is an explanation of how this works and why elements follow the octet rule. As the saying goes, all rules are made to be broken. General chemistryoctet rule and exceptions wikibooks, open. So theres two electrons here, four, six, and eight. The rule is especially applicable to carbon, nitrogen, oxygen, and the halogens, but also to metals such as sodium. This structure is held responsible for the relative inertness of the noble gases and the chemical behaviour of certain other elements. The isoelectronic principle in calculating the octet structures of molecules using the nv method, we needed to know only the number of atoms and the number of electrons, not the identities of the atoms themselves. In these simple cases where the octet rule is obeyed, the exceptions, and for which the valence is less clearly defined.
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