Since all of the electrons shown above are paired, this structure represents the most stable bonding arrangement that can be achieved by combining hydrogen and iodine. Note that by correctly executing the pairing process, iodine is surrounded by a total of eight, fully-paired dots.
However, as explained in Section 3. Instead, hydrogen is associated with two total electrons in the structure shown above and achieves a duet configuration, as expected.
This information is visually-highlighted in the structure shown below using a blue circle around hydrogen and a green box around iodine.
Finally, in order to generate a structure that is more visually-appealing, the shared pair of electrons is replaced with a line that connects the adjacent elemental symbols. The remaining electrons are redrawn as dots on the resultant structure, as shown below. In the structure that is generated upon the completion of this final step, the line represents a covalent bond, or a shared pair of electrons, and the remaining pairs of dots are called lone pairs.
The structure shown above, which is a chemically-correct representation of a covalent compound, is the Lewis structure that represents the molecule that is formed when hydrogen and iodine bond with one another. Because this molecule only contains one atom of two different elements, it is classified as a heteronuclear diatomic molecule.
Draw the Lewis structure that represents the compound that is formed when two chlorine atoms bond with one another. Two chemically-correct electron dot structures for this element are shown below. However, in the current example, each c h l o r i n e atom has the same number of unpaired electrons. Therefore, in order to satisfy the valences of each of these atoms, the unpaired electrons on each c h l o r i n e atom must be paired, in order to create a shared pair of electrons.
This structure contains one shared pair of electrons, which was created by pairing the unpaired electrons on each c h l o r i n e atom. As this electron pair is located in between both c h l o r i n e electron dot structures, these electrons contribute to the overall electron configuration of both atoms. By correctly executing the pairing process, each c h l o r i n e atom is surrounded by a total of eight, fully-paired dots. This information is visually-highlighted in the structure shown below using a blue circle around one chlorine atom and a green box around the other chlorine atom.
As an octet configuration is the most stable electron arrangement that can be achieved by an atom, this structure represents the most stable bonding arrangement that can be achieved by combining two chlorine atoms.
The structure shown above, which is a chemically-correct representation of a covalent compound, is the Lewis structure that represents the molecule that is formed when two chlorine atoms bond with one another.
Because this molecule only contains two atoms of the same element, it is classified as a homonuclear diatomic molecule. For a covalent molecule, the information represented in its chemical formula must be a direct reflection of its Lewis structure.
Elemental symbols are incorporated into a chemical formula by counting the number of times that each symbol appears in the corresponding Lewis structure. In order to ensure consistent formatting, the elemental symbol that appears fewer times is written first in a covalent chemical formula, and subscripts are used to indicate how many times each elemental symbol appears in the Lewis structure. As indicated previously, values of "1" are usually implicitly-understood in chemistry and, therefore, should not be written in a chemical formula.
The subscripts must not be reduced to the lowest-common ratio of whole numbers, even if it is mathematically-possible to do so , as dividing the subscripts would cause their values to be inconsistent with the number of times that each elemental symbol appears in the Lewis structure.
The chemical formula of a heteronuclear diatomic molecule can be determined using a modified version of the rules presented above. For example, consider the Lewis structure shown below, which represents the covalent molecule that is formed when hydrogen and iodine bond with one another. This Lewis structure contains one hydrogen atom and one iodine atom. As stated above, the elemental symbol that appears fewer times is typically written first in a covalent chemical formula.
However, in the current example, the elements are present in equal quantities. As a result, the order in which the elemental symbols are written in the corresponding chemical formula must be determined using a secondary rule: The elemental symbol for the element that is farther away from fluorine on the periodic table is written first. Therefore, the elemental symbol for hydrogen , " H ," is written before iodine's elemental symbol, " I.
The resultant chemical formula, H I , accurately summarizes the information in the Lewis structure shown above and, therefore, is the chemically-correct formula for this covalent molecule.
The chemical formula of a homonuclear diatomic molecule can be determined using a modified version of the rules presented above. For example, consider the Lewis structure shown below, which represents the covalent molecule that is formed when two chlorine atoms bond with one another. As only one type of element is present in this Lewis structure, only one elemental symbol, " Cl ," is written in the corresponding chemical formula.
Furthermore, because this Lewis structure contains two chlorine atoms, a subscript of " 2 " should be written on c h l o r i n e ' s elemental symbol. The resultant chemical formula, Cl 2 , accurately summarizes the information in the Lewis structure shown above and, therefore, is the chemically-correct formula for this covalent molecule.
For a covalent molecule, the information represented in its chemical name must also be a direct reflection of its Lewis structure. Therefore, the chemical name of a covalent molecule must contain information that indicates the identities of its constituent elements and usually reflects how many of each of those elements are present within the molecule.
Note that, if written properly, the chemical formula for a covalent molecule also contains this information and, therefore, can be used as the basis for developing a chemical name.
Elemental names are incorporated into a covalent molecule's chemical name in the order in which their corresponding elemental symbols appear in the chemical formula. The suffix on the second elemental term is replaced with "-ide," in order to indicate its secondary placement within the chemical formula. Finally, since the subscripts in a covalent chemical formula are used to indicate how many times each elemental symbol appears in the molecule's Lewis structure, corresponding numerical prefixes are usually incorporated into the molecule's chemical name.
Remember that the prefix " mono- " is never used to change the first elemental term in a covalent chemical name and should only be used as a modifier on the remaining term if the secondary element is oxygen. Finally, an "a" or "o" at the end of a prefix is usually dropped if the name of the element that is being altered begins with a vowel. The chemical name of a heteronuclear diatomic molecule can be determined using the rules presented above.
For example, consider HI, the molecule that is formed when hydrogen and iodine bond with one another. Since the elemental symbol " H " appears first in the given chemical formula, " hydrogen " is the basis of the first word in the molecule's chemical name.
The subscript on this elemental symbol, an unwritten " 1 ," corresponds to prefix of " mono-. Therefore, the first word in the chemical name of this molecule is " hydrogen.
Because the elemental symbol " I " is written second in the given chemical formula, " iodide " becomes the basis of the second word in the molecule's chemical name. The suffix on this elemental term is "-ide," as an indicator of its secondary placement within the chemical formula.
Because the secondary element is iodine , the " mono- " prefix is not applied. Therefore, the second word in the chemical name of this molecule is " iodide. The result of combining these words, " hydrogen iodide ," is the chemically-correct name for H I. Because a homonuclear diatomic molecule contains only a single element, the rules that are typically used for naming covalent molecules are not applicable.
Instead, the term "molecular" is written as the first word in the chemical name of a homonuclear diatomic molecule, as an indicator that only a single element is present. Like the diatomic elements, these compounds are gases at room temperature. At room temperature, the element lithium is a solid and does not form diatomic molecules.
However, if you heat it up enough such that it becomes a gas, the gas phase is a diatomic molecule. Other elements that also form diatomic molecular gases include sulfur as disulfur, tungsten as ditungsten, and carbon as dicarbon. Oxygen, nitrogen and the other diatomic molecules that are gases at room temperature remain diatomic at temperatures low enough to turn them to liquids.
Forces weaker than atomic bonds that attract neighboring molecules allow them to enter the liquid state when low temperatures slow the molecules down sufficiently. Chicago native John Papiewski has a physics degree and has been writing since He has contributed to "Foresight Update," a nanotechnology newsletter from the Foresight Institute.
Special Properties of Hydrogen. What Is a Noble Gas Configuration? What Are the Properties of Ionic Crystals? Characteristics of Ionic and Covalent Compounds. What Type of Bonding Occurs in Tungsten? Number of Protons in an Uncharged Atom. Covalent Vs.
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