Duet rules

When atoms combine to produce molecules, they often do so in accord with the octet rule. Your text undoubtedly contains a fairly detailed discussion of the octet rule. In essence, it may be described as the tendency for an atom to lose, gain, or share electrons in order to achieve an s2p6 configurationin 1 e 0uter most shell. The simplest atoms (H, Li, Be, and so on) tend to achieve a Is2 configuration, according to what might be called the duet rule. 

Arrange the remaining electrons around the atoms to satisfy the duet rule for hydrogen and the octet rule for other atoms. 

Because the maximum number of electrons in the first shell of an atom is 2, helium is stable with 2 electrons in its only occupied shell. The other very light elements—hydrogen, lithium, and beryllium—tend to form stable states by achieving the 2-electron configuration of helium. Having 2 electrons in the first shell, when that is the only shell and therefore the outermost shell, is a stable state, and the 2 electrons are sometimes called a duet. When there is only one shell, 2 electrons in that shell act like 8 electrons in any other outermost shell. Therefore, an atom with 2 electrons in its outermost first shell is often said to obey the octet rule, although duet rule would be more precise. 

Hydrogen forms stable molecules where it shares two electrons. That is, it follows a duet rule. For example, when two hydrogen atoms, each with one electron, combine to form fhe H2 molecule, we have... 

Lewis structure Duet rule Octet rule Bonding pair... 

When atoms form covalent bonds, they try to attain a valence-electron configuration similar to that of the nearest noble gas element. Thus hydrogen in a bond would have two electrons (like helium, the duet rule) and others would have eight electrons (like neon and argon, the octet rule). 

Write Lewis structures that obey the octet rule (duet rule for H) for each of the following molecules. Carbon Is the central atom In CH4, nitrogen Is the central atom In NH3, and oxygen Is the... 

Write Lewis structures that obey the octet rule (duet rule for H) for each of the following molecules. 

Give a rationale for the octet rule and the duet rule for H in terms of orbitals. 

Lewis structures are drawn to represent the arrangement of the valence electrons in a molecule. The rules for drawing Lewis structures are based on the observation that nonmetal atoms tend to achieve noble gas electron configurations by sharing electrons. This leads to a duet rule for hydrogen and to an octet rule for many other atoms. 

In writing Lewis structures for molecules, what is meant by the duet rule To which element does the duet rule apply What do we mean by the octet rule Why is attaining an octet of electrons important for an atom when it forms bonds to other atoms What is a bonding pair of electrons What is a nonbonding (or lone) pair of electrons ... 

Duet rule With only a Is orbital capable of holding two electrons (Is, helium is simply too small to hold eight electrons like the rest of the noble gases. Likewise, hydrogen (Is ) wants just one electron to achieve Is, just as lithium (Is 2s ) wants to rid itself of the 2s electron to become Is. ... 

The octet and duet rules that were introduced in Lecture 2 are very powerful. It turns out, however, that some specific atoms may occasionally exceed the octet and establish electron-rich molecules. Chemists still argue with passion whether this is the case or that octet and duet are forever (see Retouches section 6.R.1). Nevertheless, as electron richness is a very didactic concept for constructing some important molecules, one of which is phosphoric acid, which is a constituent of DNA and RNA, we shall not worry about the hot debate of the chemists, but instead use electron richness as an element in our molecular construction. 

However, this is not the only way to pair up the electrons in the molecule. If you were a stavmch adherent of the octet rule, you could have shifted one of the electron pairs of the F O bond in the electron-rich formulation and placed these two electrons on oxygen. Since oxygen gained now an electron, and phosphorus lost one, the FMD bond will become a single bond, but its atoms will be charged, which we can represent as 0 . Now, all the atoms obey the octet rule (and H obeys the duet rule), and we all have peace... 

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