Electron dot structures or Lewis dot formula can be drawn if the molecular formula of the compound is known. It defines the nature of bond and position of atoms of the molecule which are connected in the molecule. The Na + cation and the Cl-anion are held together by electrostatic or ionic bonds.There is no sharing in ionic bonding. The anion takes the electron for itself and the cation is happy to get rid of its electron. The ions in ionic compounds are arranged in three-dimensional structures.
Every chemistry student has to learn how to draw Lewis Dot Structures. The key is to understand the steps and practice. Lewis Structures are important to learn because they help us predict:
- the shape of a molecule.
- how the molecule might react with other molecules.
- the physical properties of the molecule (like boiling point, surface tension, etc.).
That helps us understand and predict interactions with things like medicine and our body, materials used to make buildings and airplanes, and all sorts of other substances. Lewis structures don't tell us everything, but along with molecule geometry and polarity they are hugely informative.
Search 100+ Lewis Structures on our site.
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Click the Chemical Formula to see the Lewis Structure | Acetone | (C3H6O) | | AsCl3 | (Arsenic Trichloride) | | AsF3 | (Arsenic Trifluoride) | | AsF5 | (Arsenic Pentafluoride) | | AsF6- | (AsF6-) | | AsH3 | (Arsenic Trihydride) | | AsO33- | (Arsenite Ion) | | BBr3 | (Boron Tribromide) | | BCl3 | (Boron Trichloride) | | BF3 | (Boron Trichloride) | | BF4- | (Tetrafluoroborate Ion) | | BH3 | (Boron Hydride) | | BH4- | (BH4-) | | B(OH)3 | (B(OH)3) | | BeCl2 | (Beryllium Chloride) | | BeF2 | (Beryllium Fluoride) | | BeH2 | (Beryllium Hydride) | | Br2 | (Bromine Gas or Elemental Bromine) | | Br3- | (Tribromide Ion) | | BrF | (Bromine Monofluoride) | | BrF2 | (Bromine Difluoride) | | BrCl3 | (Bromine Trichloride) | | BrF3 | (Bromine Trifluoride) | | BrF5 | (Bromine Pentafluoride) | | BrO- | (Hypobromite Ion) | | BrO2- | (Bromite Ion) | | BrO3- | (Bromate Ion) | | C22- | (Dicarbide Ion) | | CBr4 | (Carbon Tetabromide) | | CCl4 | (Carbon Tetachloride) | | ClF | (Chlorine Monofluoride) | | CF2Cl2 | (Dichlorodifluoromethane) | | CH2Cl2 | (CH2Cl2) | | CH3- | (CH3-) | | CH3Br | (CH3Br) | | CH3Cl | (Chloromethane or Methyl Chloride) | | CH3CN | (Acetonitril or Methyl Cyanide) | | CH3COO- | CH3COO- | | CH3COOH | (Acetic Acid) | | CH3F | (CH3F) | | CH3NH2 | (Methylamine) | | CH3NO2 | (CH3NO2) | | CH3OCH3 | (Dimethyl Ether or Methoxymethane) | | CH3OH | (Methanol or Methyl Alcohol) | | CH4 | (Methane) | | C2F4 | (C2F4) | | C2H2 | (Ethyne or Acetylene) | | C2H2Br2 | (C2H2Br2) | | C2H2Cl2 | (C2H2Cl2) | | C2H4 | (Ethene) | | C2H6 | (Ethane) | | C2H6O | C2H6O | | C3H6 | (C3H6) | | C3H8 | (Propane) | | C4H10 | (Butane) | | C6H6 | (Isomers - including Benzene) | | C6H12 | (C6H12) | | CHCl3 | (Chloromethane) | | CH2F2 | (Difluoromethane) | | CH2O | (Methanal or Formaldehyde) | | CH4O | (CH4O) | | Cl2 | (Chlorine Gas or Elemental Chlorine) | | Cl2CO | (Cl2CO) | | Cl2O | (Dichlorine Monoxide) | | Cl3PO | (Phosphoryl Trichloride) | | ClF3 | (Chlorine Trifluoride) | | ClF5 | (Chlorine Tetrafluoride) | | ClO- | (Hypochlorite Ion) | | ClO2 | (Chlorine Dioxide) | | ClO2- | (Chlorite Ion) | | ClO3- | (Chlorate Ion) | | ClO4- | (Perchlorate Ion) | | CO | (Carbon monoxide) | | CO2 | (Carbon Dioxide) | | CO32- | (Carbonate Ion) | | COCl2 | (COCl2) | | COF2 | (COF2) | | COH2 | (COH2) | | CN- | (Cyanide Anion) | | CS2 | (Carbon Disulfide) | | F2 | (Fluorine Gas, Difluorine) | | H2 | (Hydrogen Gas or Elemental Hydrogen) | | H2CO | (Formaldehyde or Methanal) | | H2CO3 | (Carbonic Acid) | | H2O | (Water or Dihydrogen monoxide) | | H3O+ | (Hydronium Ion) | | H2O2 | (Hydrogen Peroxide or Dihydrogen Dioxide) | | HBr | (Hydrogen Bromide or Hydrobromic Acid) | | HF | (Hydrogen Fluoride or Hydrofluoric Acid) | | HCCH | (Ethyne) | | HCl | (Hydrogen Chloride or Hydrochloric Acid) | | HCO2- | (Formate Ion) | | HCO3- | (Hydrogen Carbonate Ion or Bicarbonate Ion) | | HCOOH | (Methanoic Acid or Formic Acid) | | HI | (Hydrogen Iodide or Hydroiodic Acid) | | HClO3 | (Chloric Acid) | | HCN | (Hydrogen Cyanide) | | HNO2 | (Nitrous Acid) | | HNO3 | (Nitric Acid) | | H2S | (Dihydrogen Sulfide) | | HOCl | (Hypochlorous Acid) | | H2Se | (Dihydrogen Selenide) | | HSO3- | (Bisulfite Ion) | | HSO4- | (Bisulfate Ion) | | H2SO3 | (Sulfurous Acid) | | H2SO4 | (Sulfuric Acid) | | H3PO4 | (Phosphoric Acid) | | I2 | (Iodine Gas or Elemental Iodine) | | I3- | (I3-) | | IBr2- | (IBr2-) | | ICl | (Iodine Chloride) | | ICl2- | (ICl2-) | | ICl3 | (ICl3) | | ICl4- | (ICl4-) | | ICl5 | (Iodine Pentachloride) | | IF2- | (IF2-) | | IF3 | (Iodine Trifluoride) | | IF4- | (IF4-) | | IF5 | (Iodine Pentafluoride) | | IO3- | (Iodate Ion) | | IO4- | (Perioiodate Ion) | | N2 | (Nitrogen Gas, also called Elemental Nitrogen) | | N3- | (Azide Ion) | | N2F2 | (Dinitrogen Difluoride) | | N2H2 | (Dinitrogen Dihydride) | | N2H4 | (Dinitrogen Tetrahydride or Hydrazine or Diamine) | | N2O3 | (Dinitrogen Trioxide) | | N2O4 | (Dinitrogen Tetroxide) | | N2O5 | (Dinitrogen Pentoxide) | | NCl3 | (Nitrogen Trichloride) | | NF3 | (Nitrogen Trifluoride) | | NH2- | (NH2-) | | NH2Cl | (Chloroamine) | | NH2OH | (Hydroxylamine) | | NH3 | (Ammonium or Nitrogen Trihydride) | | NH4+ | (Ammonium Ion) | | NI3 | (Nitrogen Triiodide) | | NO+ | (Nitrosonium Ion) | | NO | (Nitric Oxide or Nitrogen Monoxide) | | N2O | (Nitrous Oxide or Dinitrogen Monoxide) | | NO2 | (Nitrogen Dioxide) | | NO2- | (Nitrite Ion) | | NO2Cl | (NO2Cl) | | NO2F | (NO2F) | | NO3- | (Nitrate Ion) | | NOBr | (Nitrosyl Bromide) | | NOCl | (Nitrosyl Chloride) | | NOF | (Nitrosyl Fluoride) | | O2 | (Oxygen Gas, also called Elemental Oxygen) | | O22- | (Perioxide Ion) | | O3 | (Ozone) | | O3 | O3 Resonance Structures | | OCl2 | (OCl2) | | OCN- | (Cyanate Ion) | | OCS | (OCS) | | OF2 | (Oxygen Difluoride) | | OH- | (Hydroxide Ion) | | PBr3 | Phosphorus Tribromide | | PBr5 | Phosphorus Pentabromide | | PCl3 | Phosphorus Trichloride | | PCl4- | PCl4- | | PCl5 | Phosphorus Pentachloride | | PF3 | Phosphorus Trifluoride | | PF5 | Phosphorus Pentafluoride | | PF6- | Hexafluorophosphate Ion | | PH3 | Phosphorus Trihydride | | POCl3 | Phosphoryl Chloride or Phosphorus Oxychloride | | PO33- | (Phosphite Ion) | | PO43- | (Phosphate Ion) | | SBr2 | (Sulfur Dibromide) | | SCl2 | (Sulfur Dichloride) | | SCl4 | (Sulfur Tetrachloride) | | SCN- | (Thiocyanate) | | SeF4 | (Selenium Tetrafluoride) | | SeF6 | (Selenium Hexafluoride) | | SeO2 | (Selenium Dioxide) | | SF2 | (Sulfur Difluoride) | | SF4 | (Sulfur Tetrafluoride) | | SF6 | (Sulfur Hexafluoride) | | S2Cl2 | (Diulfur Dichloride) | | SiCl4 | (Silicon Tetrachloride) | | SiF4 | (Silicon Tetrafluoride) | | SiF62- | (Silicon Hexafluoride Ion) | | SiH4 | (Silicon Tetrahydride) | | SiO2 | (Silicon Dioxide) | | SnCl2 | (Tin (II) Chloride) | | SOCl2 | (SOCl2) | | SO2 | (Sulfur Dioxide) | | SO3 | (Sulfur Dioxide) | | SO32- | (Sulfite Ion) | | SO42- | (Sulfate Ion) | | Water | (H2O) | | XeCl4 | Xenon Tetrachloride | | XeF2 | XeF2 | | XeF4 | Xenon Tetrafluoride | | XeF6 | Xenon Hexafluoride | | XeH4 | XeO4 | | XeO3 | XeO3 | | XeO2F2 | XeO2F2 |
| Steps for Writing Lewis Structures - Find the total valence electrons for the molecule. Explain How Examples: H2S, NCl3, OH-
- Put the least electronegative atom in the center.
Note: H always goes outside.
Examples: NOCl, CF2Cl2, HCN
- Put two electrons between atoms to form a chemical bond. Examples: CH4, NH3, I2
- Complete octets on outside atoms.
Note: H only needs two valence electrons.
- If central atom does not have an octet, move electrons from outer atoms to form double or triple bonds.
Examples: O2, N2, C2H4
Advanced Steps - If you have extra electrons after the above steps add them to the central atom. Note: elements in the Period Three (usually S, P, or Xe) can have more than eight valence electrons.
Examples: ClF3, SF4,XeH4
- Check the Formal Charges to make sure you have the best Lewis Structure. Explain How
Examples: SO42-, N2O, XeO3
Notable Exceptions to the Octet Rule - H only needs 2 valence electrons.
- Be and B don’t need 8 valence electrons.
- S and P sometimes have more than 8 val. Electrons.
- Elements in Period Three, Four, etc (on the periodic table) can hold more than 8 valence electrons.
|
Learning Objectives
By the end of this section, you will be able to:
- Write Lewis symbols for neutral atoms and ions
Lewis Symbols of Monoatomic Elements
In almost all cases, chemical bonds are formed by interactions of valence electrons in atoms. To facilitate our understanding of how valence electrons interact, a simple way of representing those valence electrons would be useful.
A Lewis electron dot diagram (or electron dot diagram or a Lewis diagram or a Lewis structure) is a representation of the valence electrons of an atom that uses dots around the symbol of the element. The number of dots equals the number of valence electrons in the atom. These dots are arranged to the right and left and above and below the symbol, with no more than two dots on a side. (It does not matter what order the positions are used.)
For example, the Lewis electron dot diagram for calcium is simply
Figure 1 shows the Lewis symbols for the elements of the third period of the periodic table.
Figure 1. Lewis symbols illustrating the number of valence electrons for each element in the third period of the periodic table.
Lewis symbols can also be used to illustrate the formation of cations from atoms, as shown here for sodium and calcium:Likewise, they can be used to show the formation of anions from atoms, as shown below for chlorine and sulfur:Figure 2 demonstrates the use of Lewis symbols to show the transfer of electrons during the formation of ionic compounds.
Figure 2. Cations are formed when atoms lose electrons, represented by fewer Lewis dots, whereas anions are formed by atoms gaining electrons. The total number of electrons does not change.
Example 1: Writing Lewis DoT SYmbols of Elements
What is the Lewis electron dot diagram for each element?
- aluminum
- selenium
Show AnswerThe valence electron configuration for aluminum is 3s23p1. So it would have three dots around the symbol for aluminum, two of them paired to represent the 3s electrons (or three single dots around the atom):
The valence electron configuration for selenium is 4s24p4. In the highest-numbered shell, the n = 4 shell, there are six electrons. Its electron dot diagram is as follows:
Check Your Learning
What is the Lewis electron dot diagram for each element?
- phosphorus
- argon
Show Answer
Example 2: Writing Lewis DoT SYmbols of Ions
What is the Lewis electron dot diagram for each ion?
- Ca2+
- O2−
Show AnswerHaving lost its two original valence electrons, the Lewis electron dot diagram is just Ca2+.
Ca2+
The O2− ion has gained two electrons in its valence shell, so its Lewis electron dot diagram is as follows:
Check Your Learning
The valence electron configuration of thallium, whose symbol is Tl, is 6s25d106p1. What is the Lewis electron dot diagram for the Tl+ ion?
Show Answer
Key Takeaways
- Lewis electron dot diagrams use dots to represent valence electrons around an atomic symbol.
- Lewis electron dot diagrams for ions have fewer (for cations) or more (for anions) dots than the corresponding atom.
Exercises
1. Explain why the first two dots in a Lewis electron dot diagram are drawn on the same side of the atomic symbol.
2. Is it necessary for the first dot around an atomic symbol to go on a particular side of the atomic symbol?
Ionic Vs Covalent Lewis Structure
3. What column of the periodic table has Lewis electron dot diagrams with two electrons?
4. What column of the periodic table has Lewis electron dot diagrams that have six electrons in them?
5. Draw the Lewis electron dot diagram for each element.
a) strontium
b) silicon
6. Draw the Lewis electron dot diagram for each element.
a) krypton
b) sulfur
7. Draw the Lewis electron dot diagram for each element.
a) titanium
b) phosphorus
8. Draw the Lewis electron dot diagram for each element.
a) bromine
Lewis Dot Ionic Bonding Worksheet
b) gallium
9. Draw the Lewis electron dot diagram for each ion.
a) Mg2+
b) S2−
10. Draw the Lewis electron dot diagram for each ion.
a) In+
b) Br−
11. Draw the Lewis electron dot diagram for each ion.
a) Fe2+
b) N3−
12. Draw the Lewis electron dot diagram for each ion.
a) H+
b) H−
Show Select Answer1. The first two electrons in a valence shell are s electrons, which are paired.
3. The second column of the periodic table
5.
a)
b)
7.
a)
b)
9.
a) Mg2+
b)
11.
a) Fe2+
b)