Electron Dot Diagram Periodic Table

63 Lewis Electron Dot Diagrams

Learning Objective

1. Describe a Lewis electron dot diagram for an cantlet or a monatomic ion.

In almost all cases, chemical bonds are formed past interactions of valence electrons in atoms. To facilitate our understanding of how valence electrons interact, a elementary 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 cantlet. These dots are arranged to the correct and left and above and below the symbol, with no more than than ii dots on a side. (It does not matter what order the positions are used.) For case, the Lewis electron dot diagram for hydrogen is simply

Because the side is not important, the Lewis electron dot diagram could too be drawn as follows:

The electron dot diagram for helium, with two valence electrons, is equally follows:

By putting the two electrons together on the same side, we emphasize the fact that these two electrons are both in the anesouth subshell; this is the common convention we volition adopt, although there will be exceptions later. The adjacent atom, lithium, has an electron configuration of anesouthward ²iis ¹, then it has just one electron in its valence shell. Its electron dot diagram resembles that of hydrogen, except the symbol for lithium is used:

Glucinium has two valence electrons in its 2s shell, so its electron dot diagram is like that of helium:

The next atom is boron. Its valence electron shell is 2s ²2p ^one, and then it has three valence electrons. The tertiary electron will go on another side of the symbol:

Again, it does not matter on which sides of the symbol the electron dots are positioned.

For carbon, in that location are four valence electrons, 2 in the 2s subshell and two in the iip subshell. Every bit usual, nosotros will describe two dots together on one side, to represent the 2s electrons. Even so, conventionally, we draw the dots for the two p electrons on different sides. Equally such, the electron dot diagram for carbon is as follows:

With nitrogen, which has 3 p electrons, we put a single dot on each of the three remaining sides:

For oxygen, which has four p electrons, nosotros now have to start doubling up on the dots on ane other side of the symbol. When doubling up electrons, make sure that a side has no more than 2 electrons.

Fluorine and neon take 7 and viii dots, respectively:

With the side by side element, sodium, the process starts over with a single electron because sodium has a single electron in its highest-numbered trounce, the n = 3 shell. By going through the periodic table, we see that the Lewis electron dot diagrams of atoms will never have more than 8 dots effectually the atomic symbol.

Example i

What is the Lewis electron dot diagram for each element?

1. aluminum
2. selenium

Solution

1. The valence electron configuration for aluminum is 3s ²3p ¹. So it would take three dots around the symbol for aluminum, two of them paired to stand for the threesouthward electrons:

   

2. The valence electron configuration for selenium is 4southward ²4p ^iv. In the highest-numbered shell, the due north = 4 shell, at that place are six electrons. Its electron dot diagram is as follows:

   

Test Yourself

What is the Lewis electron dot diagram for each chemical element?

1. phosphorus
2. argon

Reply

For atoms with partially filled d or f subshells, these electrons are typically omitted from Lewis electron dot diagrams. For example, the electron dot diagram for iron (valence shell configuration 4s ²3d ^vi) is as follows:

Elements in the same column of the periodic table have similar Lewis electron dot diagrams because they have the same valence beat electron configuration. Thus the electron dot diagrams for the commencement column of elements are as follows:

Monatomic ions are atoms that have either lost (for cations) or gained (for anions) electrons. Electron dot diagrams for ions are the aforementioned as for atoms, except that some electrons have been removed for cations, while some electrons have been added for anions. Thus in comparing the electron configurations and electron dot diagrams for the Na cantlet and the Na⁺ ion, nosotros notation that the Na atom has a single valence electron in its Lewis diagram, while the Na⁺ ion has lost that 1 valence electron:

Technically, the valence vanquish of the Na⁺ ion is now the n = 2 shell, which has viii electrons in it. Then why do we not put eight dots around Na⁺? Conventionally, when we testify electron dot diagrams for ions, nosotros show the original valence shell of the cantlet, which in this case is the n = 3 shell and empty in the Na⁺ ion.

In making cations, electrons are commencement lost from the highest numbered shell, not necessarily the concluding subshell filled. For case, in going from the neutral Fe atom to the Fe²⁺ ion, the Fe atom loses its two ivs electrons outset, not its 3d electrons, despite the fact that the 3d subshell is the last subshell being filled. Thus we have

Anions have extra electrons when compared to the original atom. Here is a comparison of the Cl cantlet with the Cl⁻ ion:

Instance 2

What is the Lewis electron dot diagram for each ion?

1. Caⁱⁱ⁺
2. O²⁻

Solution

1. Having lost its ii original valence electrons, the Lewis electron dot diagram is just Ca^two+.

   Ca²⁺

2. The O²⁻ ion has gained 2 electrons in its valence shell, so its Lewis electron dot diagram is equally follows:

   

Test Yourself

The valence electron configuration of thallium, whose symbol is Tl, is 6s ²5d ¹⁰vip ¹. What is the Lewis electron dot diagram for the Tl⁺ ion?

Respond

Key Takeaways

• Lewis electron dot diagrams use dots to correspond valence electrons effectually an diminutive symbol.
• Lewis electron dot diagrams for ions accept 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 information technology necessary for the commencement dot around an atomic symbol to go on a particular side of the atomic symbol?

3. What column of the periodic table has Lewis electron dot diagrams with 2 electrons?

4. What column of the periodic table has Lewis electron dot diagrams that have half-dozen electrons in them?

5. Draw the Lewis electron dot diagram for each element.

a)  strontium

b)  silicon

vi.  Draw the Lewis electron dot diagram for each element.

a)  krypton

b)  sulfur

vii.  Draw the Lewis electron dot diagram for each chemical element.

a)  titanium

b)  phosphorus

eight.  Draw the Lewis electron dot diagram for each element.

a)  bromine

b)  gallium

9.  Draw the Lewis electron dot diagram for each ion.

a)  Mg²⁺

b)  S²⁻

x.  Describe the Lewis electron dot diagram for each ion.

a)  In⁺

b)  Br⁻

11.  Draw the Lewis electron dot diagram for each ion.

a)  Atomic number 26²⁺

b)  N³⁻

12.  Depict the Lewis electron dot diagram for each ion.

a)  H⁺

b)  H⁻

Answers

1.

The beginning two electrons in a valence trounce are southward electrons, which are paired.

3.

the 2nd column of the periodic table

5.

a)

b)

vii.

a)

b)

9.

a)   Mg²⁺

b)

11.

a)  Fe²⁺

b)

Electron Dot Diagram Periodic Table,

Source: https://ecampusontario.pressbooks.pub/introductorychemistry/chapter/lewis-electron-dot-diagrams-2/

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