How can atoms exceed the octet rule

Valence electrons can be counted using a Lewis electron dot diagram. In carbon dioxide, for example, each oxygen shares four electrons with the central carbon. These four electrons are counted in both the carbon octet and the oxygen octet because they are shared. However, many atoms below atomic number 20 often form compounds that do not follow the octet rule. For example, with the duet rule of the first principal energy level, the noble gas helium, He, has two electrons in its outer level.

Since there is no 1p subshell, 1s is followed immediately by 2s, and thus level 1 can only have at most two valence electrons. Hydrogen only needs one additional electron to attain this stable configuration, through either covalent sharing of electrons or by becoming the hydride ion :H — , while lithium needs to lose one by combining ionically with other elements.

This leads to hydrogen and lithium both having two electrons in their valence shell—the same electronic configuration as helium—when they form molecules by bonding to other elements.

There are also a variety of molecules in which there are too few electrons to provide an octet for every atom. Boron and aluminum, from Group III or 13 , display different bonding behavior than previously discussed. These atoms each have three valence electrons, so we would predict that these atoms want to bond covalently in order to gain 5 electrons through sharing to fulfill the octet rule. However, compounds in which boron or aluminum atoms form five bonds are never observed, so we must conclude that simple predictions based on the octet rule are not reliable for Group III.

Consider boron trifluoride BF 3. The bonding is relatively simple to model with a Lewis structure if we allow each valence level electron in the boron atom to be shared in a covalent bond with each fluorine atom. In this compound, the boron atom only has six valence shell electrons, but the octet rule is satisfied by the fluorine atoms.

Lewis structure of boron trifluoride : Each pair of dots represents a pair of electrons. When placed between two atoms, the electrons are in a bond. A bond can be drawn as a line between two atoms, which also indicates two electrons. We might conclude from this one example that boron atoms obey a sextet rule. However, boron will form a stable ion with hydrogen, BH 4 — , in which the boron atom does have a complete octet. In addition, BF 3 will react with ammonia NH 3 , to form a stable compound, NH 3 BF 3 , for which a Lewis structure can be drawn that shows boron with a complete octet.

Boron trifluoride-ammonia complex : This covalent compound NH 3 BF 3 shows that boron can have an octet of electrons in its valence level. If you look up general trends in the periodic table ionic size is showen to increase too. The ionic size is directly related to these larger orbital shells that hold more electrons.

Yes sulfur and phosphorus can expand the octet. They can have 12 or 10 valence electrons, respectively, when combined with small halogens. In PCl, phosphorus has 10 valence electrons. The bolded statements are true The octet rule can be violated. Atoms are most stable when their atomic number is divisible by 8.

All free atoms contribute eight valence electrons to form molecules. Only the oxygen atom can have an expandable octet. In order to obey the octet rule, some atoms have to share more than one pair of electrons. No but apples do! The tendency of some atoms to have 8 electrons in their outermost shell two e- in the S orbital and six e- in the P orbital is called the "octet rule. Octet rule and electron rule.

Atoms of metals tend to lose their valence electrons,leaving a complete octect in the next-lowest energy level. Atoms of some non-metals tend to gain electrons or to share electrons with another nonmetal to achieve a complete octet. It does for most monatomic ions, but some polyatomic ions are octet violators. They don't have enough electrons. You're going to need to give some answer choices here. There is quite an array of elements that do not necessarily have to follow the octet rule, Xenon being just one example.

An octet electron arrangement is where an atom has 8 valence electrons. It's very stable and unreactive. Some metal atoms tend to donate its electrons and the electrons accepted by non-metal atom. This is called ionic bonding. Some non-metal electron share electron among themselves to achieve octet electron arrangement. This is called covalent bonding.

Conclusion is, all elements achieve octet electron arrangement. Beryllium is in the 2d period of the modern periodic table. Its electron config. There are just enough seats on the stage for the graduates. How do you avoid getting too many people in a row and not enough in the next row? Someone is stationed at the end of the row to count the students as they enter.

Only so many are allowed to go into a row, and then you begin to fill the next row. Electrons in atoms behave the same way.

There are rules that determine where electrons go in compounds. The noble gases are unreactive because of their electron configurations. The noble gas neon has the electron configuration of 1 s 2 2 s 2 2 p 6. Related questions What is the duet rule? Does PC5 obey the octet rule? Why does B CH3 3 violate the octet rule? What element never obeys the ''octet rule'' when covalently bonding? Why is the octet rule important in covalent bonding?