Full Orbital Diagram For He

Electron Configurations

The content that follows is the substance of General Chemistry Lecture 26. In this lecture we proceed the discussion of Quantum Numbers and their use in Electron Configurations as well as the relationship of electron configuration to the periodic properties of the elements.

Electron Configuration

Electron configurations are the summary of where the electrons are around a nucleus. Equally we learned earlier, each neutral atom has a number of electrons equal to its number of protons. What nosotros will do now is identify those electrons into an arrangement around the nucleus that indicates their energy and the shape of the orbital in which they are located. Here is a summary of the types of orbitals and how many electrons each can contain:

Then based on what we know about the quantum numbers and using the chart in a higher place, y'all demand two electrons to fill an s orbital, 6 electrons to fill a p orbital, 10 electrons to fill a d orbital and 14 electrons to make full the f orbital. Just what nosotros oasis't discussed is how these orbitals get filled...the order of fill up.

Order of Make full

The order in which electrons are placed into the orbitals is based on the order of their energy. This is referred to equally the Aufbau principle. The lowest energy orbitals fill offset. Just like the quantum numbers themselves this guild was determined by calculation and is summarized by the following nautical chart:

or you can just use the periodic table:

How to Write an Electron Configuration

The symbols used for writing the electron configuration first with the shell number (due north) followed by the type of orbital and finally the superscript indicates how many electrons are in the orbital.

For case:

Looking at the periodic tabular array, y'all can run into that Oxygen has 8 electrons. Based on the club of fill up in a higher place, these 8 electrons would fill in the following club 1s, 2s and then 2p. So Oxygen'due south electron configuration would be O 1sⁱⁱ2s^two2p⁴ .

Special Cases

Configurations of ions present a special case of electron configuration and also demonstrate the reason for the germination of those ions in the first place.

If you need to write the full electron configuration for an anion, so you are merely adding additional electrons and the configuration is but connected.

For instance, we know that Oxygen ever forms ii- ions when information technology makes an ion. This would add two electrons to its normal configuration making the new configuration: O^2- 1s²2s^two2p⁶ . With 10 electrons you lot should note that oxygen's electron configuration is now exactly the same as Neon's. We talked almost the fact that ions grade because they can go more stable with the gain or loss of electrons to get like the noble gases and at present you lot can really run into how they become the same.

The electron configurations for Cations are also made based on the number of electrons but at that place is a slight difference in the way they are configured. First you should write their normal electron configuration and so when you remove electrons you have to take them from the outermost shell. Note that this is non ever the aforementioned fashion they were added.

Here is an instance of what I mean:

Atomic number 26 has 26 electrons so its normal electron configuration would exist: Iron 1s²2s^two2p⁶3sⁱⁱ3p^half-dozen4s²3d⁶

When we make a 3+ ion for Iron, we demand to take the electrons from the outermost beat out outset then that would exist the 4s shell Non the 3d vanquish: Fe^three+ 1s²2s²2p⁶3sⁱⁱ3p⁶3d^v

One other note on writing electron configurations: A short cut. When writing some of the lower table configurations the total configuration can be fairly long. In these cases, y'all can use the previous element of group 0 to abbreviate the configuration as shown below. You simply take to finish the configuration from where the noble gas leaves information technology:

Exceptions

As with every other topic we accept covered to appointment there are exceptions to the order of fill up as well. Merely based on the electron configurations that are generated, these exceptions are easy to sympathize.

In the d block, specifically the groups containing Chromium and Copper, in that location is an exception in how they are filled.

Here are the bodily configurations:

In these columns, the 4s and 3d

Practise, Do, Do

There are lots of quizzes on electron configurations you can practice with located here

Orbital Diagrams

Some other fashion to represent the society of fill for an cantlet is by using an orbital diagram oftentimes referred to as "the petty boxes":

The boxes are used to represent the orbitals and to bear witness the electrons placed in them. The order of make full is the same but as you tin meet from above the electrons are placed singly into the boxes earlier filling them with both electrons. This is called Hund's Rule: "One-half make full before you Full make full" and once again this rule was established based on energy calculations that indicated that this was the mode atoms really distributed their electrons into the orbitals.

Periodic Properties

Ane of the really cool things about electron configurations is their relationship to the periodic tabular array. Basically the periodic table was constructed and so that elements with similar electron configurations would be aligned into the same groups (columns).

Periodic Table showing terminal orbital filled for each element

The periodic table shown higher up demonstrates how the configuration of each element was aligned so that the concluding orbital filled is the aforementioned except for the vanquish. The reason this was done is that the configuration of an element gives the element its properties and similar configurations yield similar properties.

Let's get through some of the Periodic Properties that are influenced directly by the electron configuration:

Atomic Size

The size of atoms increases going down in the periodic table. This should be intuitive since with each row of the tabular array y'all are calculation a trounce (n). What is not equally intuitive is why the size decreases from left to correct. Just again the construction of the electron configuration gives us the reply. What are you doing as you go across the periodic table? Answer, calculation protons to the nucleus and adding electrons to the valence shell of the element. What is non irresolute equally you cross a menses? Answer, the inner vanquish electrons. So call back of it this style, the inner shell electrons are a shield against the pull of the nucleus. As you lot cantankerous a menstruation and increase the number of protons in the nucleus yous increase its pull just since you are only calculation electrons to the new shell the shield is not increasing but remains the aforementioned all the manner across. This ways the pull on the electrons being added to the valence shell is increasing steadily all the fashion across. What happens if yous pull harder on the electrons? Well, they come closer to the nucleus and the size of the cantlet decreases. The issue of the nucleus pulling on the electrons being added beyond a period is called the effective nuclear charge and is calculated as ZEff = #protons - Core # Electrons. Then for case the pull felt past Sulfur would be ZEff = 16 - 10 = +vi

Electronegativity

Electronegativity may exist the most important of the periodic properties you tin can larn and understand since so many other properties are depend on its value. Electronegativity is an atoms ability to pull electrons towards itself.

Electronegativity is generally expressed past the Pauling Scale and the values were determined experimentally. The table below shows the scale values for the elements.

The electronegativity values increase from left to right and bottom to tiptop in the periodic table excluding the Noble gases. The most electronegative chemical element is Fluorine.

From these electronegativity values we tin derive the patterns of ii other periodic properties: Ionization Free energy and Electron Analogousness.

	Ionization Energy Ionization energy is the amount of energy required to remove an electron from an atom. All ionization energies are positive values because all of these removals (even those for elements that form positive ions) crave input of energy. The more electronegative the element, the higher the ionization eneregy.
Electron Affinity The Electron Analogousness of an element is the amount of energy gained or released with the improver of an electron. The electronegativity and Electron Affinity increases in the aforementioned pattern in the periodic table. Left to right and bottom to height.

Full Orbital Diagram For He,

Source: https://www.chem.fsu.edu/chemlab/chm1045/e_config.html

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