With a non-metal, the atom tends to gain additional electrons until the current valence shell reaches eight. For example, sulfur has six valence electrons. Once it gains two more - which it will acquire through reaction with a metal for instance - it has eight outer electrons, and a charge of Care must be taken with the metalloids the semi-metals such as carbon and silicon, as these can be difficult to classify as electron-gainer or electron-loser.
Here, you likely need to consider each case separately, looking at the reaction it is involved in. How can we use the valence electrons and the octet rule to predict the charge an element will obtain?
When discussing the octet rule, we do not consider d or f electrons. In , Richard Abegg formulated what is now known as Abegg's rule , which states that the difference between the maximum positive and negative valences of an element is frequently eight. This rule was used later in when Gilbert N. Lewis formulated the "octet rule" in his cubical atom theory. Atoms will react to get in the most stable state possible. A complete octet is very stable because all orbitals will be full.
Atoms with greater stability have less energy, so a reaction that increases the stability of the atoms will release energy in the form of heat or light.
A stable arrangement is attended when the atom is surrounded by eight electrons. This octet can be made up by own electrons and some electrons which are shared.
The next dots, for elements with more than four valence electrons, are again distributed one at a time, each paired with one of the first four. For example, the electron configuration for atomic sulfur is [Ne]3s 2 3p 4 , thus there are six valence electrons.
Its Lewis symbol would therefore be:. Fluorine, for example, with the electron configuration [He]2 s 2 2 p 5 , has seven valence electrons, so its Lewis dot symbol is constructed as follows:. Lewis dot symbols for the elements in period 2 are given in Figure 8.
Lewis used the unpaired dots to predict the number of bonds that an element will form in a compound. Consider the symbol for nitrogen in Figure 8. The Lewis dot symbol explains why nitrogen, with three unpaired valence electrons, tends to form compounds in which it shares the unpaired electrons to form three bonds. Boron, which also has three unpaired valence electrons in its Lewis dot symbol, also tends to form compounds with three bonds, whereas carbon, with four unpaired valence electrons in its Lewis dot symbol, tends to share all of its unpaired valence electrons by forming compounds in which it has four bonds.
In , Richard Abegg formulated what is now known as Abegg's rule , which states that the difference between the maximum positive and negative valences of an element is frequently eight. This rule was used later in when Gilbert N.
Lewis formulated the "octet rule" in his cubical atom theory. The octet rule refers to the tendency of atoms to prefer to have eight electrons in the valence shell.
When atoms have fewer than eight electrons, they tend to react and form more stable compounds. Atoms will react to get in the most stable state possible. A complete octet is very stable because all orbitals will be full. Atoms with greater stability have less energy, so a reaction that increases the stability of the atoms will release energy in the form of heat or light ;reactions that decrease stability must absorb energy, getting colder.
When discussing the octet rule, we do not consider d or f electrons. Only the s and p electrons are involved in the octet rule, making it a useful rule for the main group elements elements not in the transition metal or inner-transition metal blocks ; an octet in these atoms corresponds to an electron configurations ending with s 2 p 6.
Chlorine dioxide is a bit special in not following the octet rule. The odd electron count means that there must be an unpaired electron. This unpaired electron accounts for the rather high reactivity of ClO 2. As such, chlorine dioxide uses include industrial oxidants and disinfects for drinking water and food.
The U. Food and Drug Administration describes generation and application of this fairly common chemical in 21CFR It has sulfur S bonded to six fluorine atoms F. With two electrons per bond, that makes 12 electrons for sulfur. So, as a rule, sometimes sulfur can form 6 bonds instead of the normal 2. Sulfur hexafluoride, or SF 6 , is a real chemical.
Although non-toxic to breathe, SF 6 can react to form harmful substances when exposed to certain types of electric discharges. It also acts as a greenhouse gas when it eventually leaks from electrical equipment into the atmosphere.
Although it lacks an octet, which usually makes molecules stable, SF 6 is extremely stable. Sulfur hexafluoride is estimated to float around the atmosphere for centuries. The above describes how the octet rule applies to covalent bonds, as found in molecules. There is a whole second case for how the octet rule apples for ionic bonds. Click here to learn about ionic compounds and the other case for using the octet rule.
Skip to content. Octet Rule. What is the Octet Rule? How Many Valence Electrons for Carbon? The same idea would apply to silicon Si , another element in column 4.
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