Sulfur Electron Configuration Long Form

2.7: Applications of Electron Configurations: Valence Electrons and Electron Dot Structures

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LEARNING OBJECTIVES

• Determine the number of valence electrons in an cantlet.
• Describe an electron dot structure for an atom.

Valence Electrons

As was mentioned in a previous section of this affiliate, electrons are highly important, because a specific subset of electrons, called valence electrons , are solely-responsible for determining how elements bond with one another.  The number of valence electrons that are nowadays in an atom can be determined from that cantlet'south electron configuration.  Valence electrons are found in the orbitals associated with an atom's highest occupied energy level.  The remaining electrons, which are called inner shell electrons, do non participate in bonding and are, therefore, not important to study.

Consider sulfur'due south electron configuration, which was determined in the previous section and is replicated below.

1 south ^two 2 s ² 2 p ^{half dozen} 3 s ² 3 p ⁴

Recall that the energy levels in an electron configuration are theleading crimson numbers that denote the commencement of a new energy level/orbital combination.  Sulfur has electrons in the first, second, and third energy levels, every bit indicated by the leading cherry-red ane, two's, and 3's, respectively.  Valence electrons are those institute in thehighest occupied energy level.  Therefore, in this example, only those electrons associated with anenergy level/orbital combination beginning with a3 need to be considered.  Since two energy level/orbital combinations begin with athree, both orbitals are selected for further consideration:

3 s ² 3 p ^iv

The superscripts associated with these orbitals total to 6.  Therefore, sulfur has 6 valence electrons.

Example \(\PageIndex{one}\)

Determine how many of nitrogen's electrons are classified as valence electrons.  Nitrogen'south electron configuration, which was determined in the previous section, is shown below.

1 south ^two two south ⁱⁱ two p ⁱⁱⁱ

Solution

Nitrogen has electrons in the first and secondfree energy levels, equally indicated by the leading crimson aneandii's, respectively.  Valence electrons are those found in thehighest occupied energy level.  Therefore, in this instance, only those electrons associated with anenergy level/orbital combination beginning with a2 need to be considered.  Since 2 energy level/orbital combinations begin with a2, both orbitals are selected for further consideration:

2 s ^two 2 p ^three

The superscripts associated with these orbitals total to 5.  Therefore, nitrogen has 5valence electrons.

Exercise \(\PageIndex{ane}\)

Make up one's mind how many of the electrons in each of the following elements are classified as valence electrons.  Each element'southward electron configuration, which was adamant in the previous department, is shown below.

1. Neon

one s ² 2 s ⁱⁱ 2 p ⁶

1. Calcium

1 southward ² 2 s ² 2 p ⁶ 3 due south ⁱⁱ iii p ^six 4 s ⁱⁱ

Answer a

Neon has electrons in the first and secondenergy levels, as indicated by the leading crimson 1and2's, respectively.  Valence electrons are those found in thehighest occupied free energy level.  Therefore, in this instance, only those electrons associated with anfree energy level/orbital combination beginning with a2 need to be considered.  Since two energy level/orbital combinations begin with a 2, both orbitals are selected for further consideration:

2 s ^two two p ^{half dozen}

The superscripts associated with these orbitals total to viii.  Therefore, neon has viiivalence electrons.

Answer b

Calcium has electrons in the first, second, third, and quaternaryenergy levels, as indicated past the leading red i,2's,three's, andiv, respectively.  Valence electrons are those establish in thehighest occupied energy level.  Therefore, in this example, merely those electrons associated with anfree energy level/orbital combination showtime with a4 need to be considered.  Since only 1energy level/orbital combination begins with a 4, just one orbital is selected for further consideration:

4 s ²

The superscriptassociated with thisorbital is a2.  Therefore, calcium has twovalence electrons.

While an electron configuration representsall of the electrons nowadays in an atom of an chemical element, chemists are only truly interested in an atom'southvalence electrons, since, as indicated above, those are the electrons that are solely-responsible for determining how elements bond with i another.  Therefore, finding a "shortcut" for determining how many valence electrons are present in an cantlet would be highly convenient.  Such a "shortcut" does, indeed, exist.  In a previous section of this affiliate, three systems for labeling the groups, or columns, on the periodic table were presented.  The second organisation, which is chosen the "A/B System," was indicated to provide insight into the electronic character of elements constitute within that group.

Once more, consider sulfur, Due south, which, based on its electron configuration, has6 valence electrons.

Sulfur is located in the 16^th cavalcade of the periodic table.  Nonetheless, the "A/B Organization" is used to label the main group elements .  Grouping xvi is the 6^th column in the principal grouping, or "A-Cake," columns of the periodic tabular array and so is labeled every bit Group half-dozen A .  Notation that sulfur'south valence electron count matches its grouping number in the "A/B System."  This connectedness applies to aboutall elements found in themain group columns of the periodic tabular array.  Helium is the but exception to this rule, as information technology is plant in Group 8A, but only contains two full electrons.  This inconsistency invalidates the "A/B shortcut" method, and the electron configuration method must be employed to determine that both of helium's electrons are valence electrons.

Since the "A/B System" grouping number corresponds to the number of valence electrons that are present in an cantlet, all elements found within the same column accept the same number of valence electrons.  Since an atom'southward valence electrons are solely-responsible for determining how elements bond with one another, this commonality in electronic character explains why all of the elements within the aforementioned group share similar backdrop.

Example \(\PageIndex{2}\)

Based on its location on the periodic table, determine how many of nitrogen's electrons are classified as valence electrons.

Solution

The "A/B Arrangement" grouping number indicates the number of valence electrons that are present in an atom.  Nitrogen (North) is located in the xv^th cavalcade of the periodic table.  However, the "A/B Organization" is used to label the chief group elements .  Group 15 is the 5^th cavalcade in the main group, or "A-Block," columns of the periodic table and so is labeled every bit Grouping 5A.  Therefore, nitrogen has 5 valence electrons.  (This answer is consistent with the solution to Example \(\PageIndex{i}\).)

Exercise \(\PageIndex{2}\)

Based on the periodic tabular array, decide how many of the electrons in each of the post-obit elements are classified as valence electrons.

1. Neon
2. Calcium

Answer a

The "A/B System" group number indicates the number of valence electrons that are present in an atom.  Neon (Ne) is located in Grouping 18, which is labeled every bit Group 8A, using the "A/B System."  Therefore, neon has 8 valence electrons.  (This respond is consistent with the solution to Practise \(\PageIndex{i}\text{a}\).)

Answer b

Calcium (Ca) is located in Group 2, which is labeled as Group iiA in the "A/B System."  Therefore, calcium has 2 valence electrons.  (Again, this answer is consistent with the solution to Exercise \(\PageIndex{i}\text{b}\).)

Electron Dot Structures

Electron dot structures surroundings the elemental symbol of an element with one dot for every valence electron that the chemical element contains.  When cartoon an electron dot structure, iii rules must exist followed:

1. The get-go dot tin can be placed on whatever "side" of the elemental symbol (acme, lesser, left, or right).
2. The start four dots must each be placed on their own "side" of the elemental symbol.  In other words, if the commencement dot is placed on the peak of the elemental symbol, the second dot tin can be placed on the bottom, left, or right of the symbol, butcannot exist placed at the top, alongside the starting time dot.
3. The final four dots tin once more be placed on any "side" of the elemental symbol, but must be arranged such that no more than two dots be on any "side" of the elemental symbol.

Again, consider sulfur, which has 6 valence electrons.

The elemental symbol for sulfur is S.  Since an electron dot construction surrounds an elemental symbol with one dot for everyvalence electron that the chemical element contains, sulfur's elemental symbol must exist surrounded by 6 dots.  Based on the rules given above, the dot representing sulfur's first valence electron can exist placed on any "side" of the symbol, as shown below in Effigy \(\PageIndex{1}\).

Figure \(\PageIndex{i}\): Possible first-dot placements for sulfur's electron dot structure.

If the first structure in Figure \(\PageIndex{one}\) is chosen as the basis of sulfur's electron dot structure, the dot representing sulfur's second valence electron can be placed on the bottom, left, or right of the elemental symbol, onlycannot be placed at the top, aslope the first dot.  Effigy \(\PageIndex{2}\) shows 3 structures with acceptable placements for sulfur's first two valence electrons, as well as a construction with an wrong electron system.

Effigy \(\PageIndex{2}\): Possible second-dot placements for sulfur's electron dot structure.

If the final structure in Effigy \(\PageIndex{2}\) is chosen as the basis of sulfur's electron dot structure, the dots representing sulfur's third and 4th valence electrons must be placed on the bottom and to the left of the elemental symbol, simplycannot be placed at the elevation or to the right of the elemental symbol.  Figure \(\PageIndex{3}\) shows the only construction with an adequate placement for sulfur's first 4 valence electrons.

Figure \(\PageIndex{3}\): The right four-dot placement for sulfur'due south electron dot structure.

The dots representing sulfur'southward 5th and sixth valence electrons tin again exist placed on whatsoever "side" of the elemental symbol, but cannot both exist placed on the same "side," and so that no more than two dots be on any "side" of the elemental symbol.  Figure \(\PageIndex{4}\) shows all of the structures with acceptable placements for sulfur'southward 6 valence electrons.  Therefore, any of the structures in Figure \(\PageIndex{four}\) is a valid electron dot construction for sulfur.

Figure \(\PageIndex{4}\): Valid electron dot structures for sulfur.

Instance \(\PageIndex{3}\)

Draw a valid electron dot structure for nitrogen.

Solution

The elemental symbol for nitrogen is N.  Based on Example \(\PageIndex{i}\) and Example \(\PageIndex{ii}\), nitrogen has 5 valence electrons.  Based on the rules described in a higher place, the starting time four dots must each be placed on their own "side" of the elemental symbol, and the 5th dot can be placed alongside any of the first 4.  Therefore, any of the following structures is a valid electron dot structure for nitrogen.

Exercise \(\PageIndex{iii}\)

Draw a valid electron dot construction for each of the following elements.

1. Neon
2. Calcium

Reply a

The elemental symbol for neon is Ne.  Based on Example \(\PageIndex{1}\text{a}\) and Example \(\PageIndex{2}\text{a}\), neon has 8 valence electrons.  Based on the rules described above, the get-go iv dots must each be placed on their ain "side" of the elemental symbol, and each of the remaining four dots must be placed alongside each of the first four.  Therefore, the following structure is the only valid electron dot structure for neon.

Answer b

The elemental symbol for calcium is Ca.  Based on Example \(\PageIndex{1}\text{b}\) and Example \(\PageIndex{2}\text{b}\), calcium has 2 valence electrons.  Based on the rules described above, each dot must each exist placed on its own "side" of the elemental symbol.  Therefore, any of the post-obit structures is a valid electron dot construction for calcium.

Sulfur Electron Configuration Long Form,

Source: https://chem.libretexts.org/Courses/Heartland_Community_College/CHEM_120:_Fundamentals_of_Chemistry/02:_Atoms_and_Elements/2.07:_Applications_of_Electron_Configurations_Valence_Electrons_and_Electron_Dot_Structures

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