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Chapter 4, Lesson 6 Multimedia

Lewis Dot Diagrams

A truncated version of the Periodic Table, showing Lewis Dot structures for the first 20 elements Hydrogen–Calcium.

Please click on the image above to see a larger version.

  • A Lewis dot structure is like a simplified electron energy level model.
  • The Lewis structure contains the element symbol with dots representing electrons.
  • The only electrons shown are those on the outer energy level or valence electrons.
  • The electrons are placed around the element symbol, one at a time, clockwise or counterclockwise, and then grouped in pairs as more electrons are added.

Covalent Bonding in Hydrogen

An energy level model of two hydrogens atoms alongside two lewis dot diagrams of hydrogen.Covalent bonding depicted between two energy level models of hydrogen in which all of its electrons are depicted, though only the outermost electrons participate in bonding, and between two lewis dot structures in which only the outermost electrons are shown. A covalent bond between two energy level models of hydrogen, and a simplified version of a single bonded molecule, in which the bond is represented between the two bonded atoms by a straight line. This is called bond-line formula.
  • Lewis dot structures can also be used to show the bonded atoms in a molecule.
  • The two dots together between the Hydrogens represent the electrons in the covalent bond between the hydrogen atoms.
  • The line is a short-hand version of the two dots.

Covalent Bonding in Water

Two depictions of the atoms that compose water. To the left, energy level models of two hydrogen atoms on either side of a central oxygen atom. On the right, lewis-dot structures of two hydrogen atoms and a central oxygen atom.Covalent bonding in a water molecule represented two ways. On the left, energy level models of oxygen and two hydrogens, in which the outermost electrons are shared to form bonds. On the right, lewis-dot structures for hydrogen and oxygen show pairs of shared electrons to illustrate bonding. Energy levels of hydrogen and oxygen illustrate the single bonds in water. Below, a simplified version of a water molecule in 'bond-line' formula, in which the single bonds between hydrogen and oxygen are represented by a straight line.
  • The Lewis dot structure for water shows the electron from hydrogen and an electron from oxygen being shared in a covalent bond.
  • The other four valence electrons in oxygen are in pairs at the bottom.
  • The lines are a short-hand version of the two dots representing the covalent bonds.

Covalent Bonding in Oxygen

Two representations of a pair of oxygen atoms. Above, energy level diagrams of oxygen atoms, showing all of oxygen's electrons. Below, lewis dot structures of two oxygen atoms, showing only its outermost electrons.Two depictions of an oxygen molecule. Above, energy level models show the sharing of two pairs of electrons between the atoms to illustrate the double covalent bond between them. Below, the lewis dot strucure of an oxygen molecule shows only those outermost electrons of each oxygen atom. Two depictions of an oxygen atom. Above, energy level diagrams of each oxygen atom share electrons on the outermost energy level, although all electrons for each oxygen atom are shown. Below, a 'bond-line' shorthand representation of an oxygen atom, where the double covalent bond between the oxygen atoms is represented as a pair of straight lines.
  • The two pairs of dots between the Os represent the double covalent bond in the oxygen molecule.
  • The two lines are a short-hand version of the two pairs of dots.

Covalent Bonding in Carbon Dioxide

Two depictions of a carbon atom bounded on either side by an oxygen atom. Above, energy level models of the atoms. Below, lewis dot structures of the atoms, in which only the outermost electrons are depicted, and the arranged about the chemical symbol of the atom.Two depictions of a carbon dioxide molecule. Above, using energy level models in which all the electrons in each of the atoms that compose the molecule are shown. Below, lewis dot structures are used, so only the outer electrons and chemical symbols are used. Another representation of a carbon dioxide molecule. Above, using the familiar energy level models. Below, the molecule is written in bond line formula, in which the double covalent bonds between carbon and oxygen are represented by pairs of staight lines.
  • The two pairs of dots between the C and the Os represent the double covalent bond between the carbon and each oxygen atom in the carbon dioxide molecule.
  • The two sets of two lines are a short-hand version to show the two double covalent bonds.

Ionic Bonding of Sodium Chloride

Two depictions of a sodium atom and a chlorine atom. Above, energy level models of the atoms. Below, lewis dot structures of the atoms, in which only the outermost electrons are depicted, and the arranged about the chemical symbol of the atom.Two depictions of a sodium ion in proximity to a chloride ion. Above, energy level models of the ions, with a plus sign below the sodium and a minus sign below the chloride to indiciate their charged nature. Below, lewis dot structures of the atoms, in which only the outermost electrons are depicted. Two depictions of a sodium chloride formula unit. Above, using the familiar energy level models with a plus and minus to indicate that they are ions. Below, using lewis dot structures, where the chemical symbols are surrounded by the number of electrons in the charged species and accented by a superscript charge sign to show that they are ions.
  • When sodium loses its only valence electron to become an ion, the Lewis structure shows it with no dots (electrons).
  • The Na and Cl are near each other but the two dots from the Cl should not be interpreted as a covalent bond.

Ionic Bonding in Calcium Chloride

Two depictions of a calcium atom and two chlorine atoms. Above, energy level models of the atoms. Below, lewis dot structures of the atoms, in which only the outermost electrons are depicted, and the arranged about the chemical symbol of the atom.Two depictions of a calcium ion in proximity to two chloride ions. Above, energy level models of the ions, with a plus sign below the sodium and a minus sign below the chloride to indiciate their charged nature. Below, lewis dot structures of the atoms, in which only the outermost electrons are depicted. Two depictions of a calcium chloride formula unit. Above, using the familiar energy level models with a plus and minus to indicate that they are ions. Below, using lewis dot structures, where the chemical symbols are surrounded by the number of electrons in the charged species and accented by a superscript charge sign to show that they are ions.
  • When calcium loses its two valence electrons to become an ion, the Lewis structure shows it with no dots (electrons).
  • The Ca and Cls are near each other but the two dots from each Cl should not be interpreted as a covalent bond.