What is the octet rule and which elements obey the octet rule?
What is the octet rule and which elements obey the octet rule?
The octet rule states that atoms tend to form compounds in ways that give them eight valence electrons and thus the electron configuration of a noble gas. An exception to an octet of electrons is in the case of the first noble gas, helium, which only has two valence electrons.
Does Li follow the octet rule?
Lithium, an alkali metal with three electrons, is also an exception to the octet rule. Lithium tends to lose one electron to take on the electron configuration of the nearest noble gas, helium, leaving it with two valence electrons. There are two ways in which atoms can satisfy the octet rule.
Why do Li be and H do not follow the octet rule?
H and He are exceptions to the Octet Rule because for them, a full shell is only 2 electrons (the 1s shell). Li and Be are metals, and so they are likely to lose electrons and become cations (Li+, Be2+). When that happens, they also revert to the “noble gas” configuration of He, which is 2 electrons.
What does the octet rule state?
…are expressed by his celebrated octet rule, which states that electron transfer or electron sharing proceeds until an atom has acquired an octet of electrons (i.e., the eight electrons characteristic of the valence shell of a noble gas atom). When complete transfer occurs, the bonding is ionic.
What is octet rule write its limitation?
Limitations of the octet theory: 1) The main limitation to the rule is hydrogen, which is at its lowest energy when it has two electrons in its valence shell. Helium (He) is similar in that it, too, only has room for two electrons in its only valence shell. Hydrogen and helium have only one electron shell.
What are the two limitations of octet rule?
Octet rule fails to explain the following: (1) The stability of incomplete octet molecules, i.e., the molecules with the central atom containing less than eight electrons. (2) The stability of expanded octet molecules, i.e., the molecules with the central atom containing more than eight electrons.
Why is octet rule important?
The octet rule is important because it predicts how atoms will bond based on their outer shell of valance electrons.
What are limitations of VBT?
Limitations of Valence Bond Theory No insight offered on the energies of the electrons. The theory assumes that electrons are localized in specific areas. It does not give a quantitative interpretation of the thermodynamic or kinetic stabilities of coordination compounds. No distinction between weak and strong ligands.
Why is the octet rule not universal?
The octet rule mainly applies to the second and third period elements of the modern periodic table. Any bond is not completely ionic or completely covalent, when the octet rule is applied to some molecules which have almost equal ionic and covalent characteristics, this rule fails.
What was the octet rule Why did it fail?
Failure of octet rule : There are number of stable molecules known in which the octet rule is violated that is atoms in these molecules have number of electrons in the valency shell either short of octet or more than octet. BeF2, BF3, AlH3 are electron- deficients (Octet incomplete) hence are Lewis acid.
What is Duplet rule?
There is another rule, called the duplet rule, that states that some elements can be stable with two electrons in their shell. Hydrogen and helium are special cases that do not follow the octet rule but the duplet rule. They contain an s s s orbital but no p p p orbitals.
Which is more stable Duplet or octet?
Summary – Octet vs Duplet All elements tend to become stable. The atoms or molecules which obey the octet or duplet rule are stable. The key difference between octet and duplet is that octet has eight electrons in its outermost orbital whereas duplet has two electrons in its orbital.
Why Duplet is applied in K shell?
Answer: Only Hydrogen and Helium have just a K-shell so, they are the only elements that follow duplet rule. Hydrogen atoms have 1 electron in their K-shell naturally, if they gain one more electron, they will have 2 electrons.
What is the difference between Duplet and octet rule?
Octet means presence of a total of 8 electrons in its valence shell while in case of duplet only 2 electrons are present in valence shell.
What is Duplet and octet?
The tendency of an atom to acquire 2 electrons in outermost shell . Atoms with low atomic number such as hydrogen and helium followed the duplet rule. What is Octet? Atom with 8 electrons in its outermost shell is called octet .
Does Li follow Duplet rule?
The only elements known to follow the this rule are Hydrogen, Helium and Lithium. Where hydrogen gains and shares electrons as it has only one electron less than the duplet, and lithium loses an electron to attain a duplet.
Does beryllium follow Duplet rule?
Re: Beryllium exception Beryllium and lithium both form a duplet instead of forming an octet. This is mainly related to the fact that the energy required to give Li and Be a full octet is much higher than the energy required to give up one or two electrons and form a duplet (the same way as helium does).