Multielectron System

According to Pauli's principle, "No two electrons in an atom can have same values for the spin quantum number". So only two electrons are accommodated in the same atomic orbital. According to Hund's rule,"Electrons are only filled in paired when all the orbitals of a subshell are filled singly and have the same direction of spin". Now, according to Aufbau Principle,"Electrons are filled first to an orbital with a lower energy and then fill the orbital with the higher energy and so on.

Summary

Things to Remember

The atomic orbital can accommodate only two electrons.
The electronic configuration of a Nitrogen atom is 1s² 2s² 2P³and the p-orbital is unpaired.
The 4s atomic orbital has lower energy than 3d orbital so the according to Aufbau Principle, 4s orbital is filled first.
The half filled and completely filled subshell are more stable due to the symmetrical distribution of electrons and due to exchange energy.

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Subjective Questions

Q1:

Define arthritis.

Type: Very_short Difficulty: Easy

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Q2:

List down the causes and symptoms of arthritis.

Type: Short Difficulty: Easy

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Answer: Causes of arthritis
<ul>
<li>Genetic: Exactly how much heredity or genetics contributes to the cause of arthritis is not well understood. However, there are likely genetic variation that can contribute to the causes of arthritis.</li>
<li>Age: Cartilage becomes more brittle with age and has less of a capacity to repair itself. People grow older they are more likely to develop arthritis.</li>
<li>Weight: Because joint damage is partly dependent on the load the joint has to support, excess body weight can lead to arthritis. This is especially true of the hips and knee that can be worn quickly in the heavier patient.</li>
<li>Previous Injury: Joint damage can cause irregularities in the normal smooth joint surface. PREVIOUS major injuries can be part of the causes of arthritis.</li>
<li>Occupational Hazard: Worker in some specific occupational seems to have a higher risk of developing arthritis than another job.</li>
<li>Some High-Level Sport: It is difficult to determine how much sports participation contribute to a development of arthritis.</li>
<li>Illness or Infection: People who experience a joint infection, multiple episodes of gout, or other medical condition, can develop arthritis of the joint.</li>
</ul>
Signs and symptom
The symptom of arthritis depends on the type arthritis on the types of arthritis, for example;
<ul>
<li>Osteoarthritis: The symptoms develop slowly and get worse as time goes by .There is a pain in a joint, either during or after use or after a period of inactivity.</li>
<li>Rheumatoid arthritis: The patient often finds the same joint on each side of the body are painfully swollen, inflamed and stiff. The finger, arms, legs and wrist are most commonly affected.</li>
<li>Infectious arthritis: The patient has a fever joint inflammation and swelling. He will feel tenderness and \or a sharp pain.</li>
<li>Juvenile rheumatoid arthritis: The patient is a child .HE will experience intermittent fevers which tend to peak in the evening and then suddenly disappear.</li>
</ul>
Overall symptoms of arthritis: Arthritis causes joint pain , swelling , stiffness and limited movement. Symptoms can include:
<ul>
<li>Joint pain</li>
<li>Joint swelling</li>
<li>Reduced ability to move the joint</li>
<li>Reduced to the skin around a joint</li>
<li>Stiffness , especially in the morning</li>
<li>Warmth around a joint</li>
</ul>

Q3:

Explain in detail about arthritis.

Type: Long Difficulty: Easy

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Answer: Arthritis
The word arthritis comes from the Greek arthon meaning ‘’inflammation’’. Arthritis is not a single disease – it is a term that covers 100 medical conditions. Osteoarthritis is the common form of arthritis and generally affect an elderly patient. Some form of arthritis can affect people at a very early age.
Causes of arthritis
<ul>
<li>Genetic: Exactly how much heredity or genetics contributes to the cause of arthritis is not well understood. However, there are likely genetic variation that can contribute to the causes of arthritis.</li>
<li>Age: Cartilage becomes more brittle with age and has less of a capacity to repair itself. People grow older they are more likely to develop arthritis.</li>
<li>Weight: Because joint damage is partly dependent on the load the joint has to support, excess body weight can lead to arthritis. This is especially true of the hips and knee that can be worn quickly in the heavier patient.</li>
<li>Previous Injury: Joint damage can cause irregularities in the normal smooth joint surface. PREVIOUS major injuries can be part of the causes of arthritis.</li>
<li>Occupational Hazard: Worker in some specific occupational seems to have a higher risk of developing arthritis than another job.</li>
<li>Some High-Level Sport: It is difficult to determine how much sports participation contribute to a development of arthritis.</li>
<li>Illness or Infection: People who experience a joint infection, multiple episodes of gout, or other medical condition, can develop arthritis of the joint.</li>
</ul>
Types of arthritis
<ul>
<li>Osteoarthritis: Cartilage loses its elasticity .If the cartilage is stiff it becomes damaged more easily. The cartilage, which acts as a shock absorbs will gradually wear away in some area.</li>
<li>Rheumatoid arthritis: This is an inflammatory is attacked, resulting in swelling and pain .If left untreated arthritis can lead to deformity. Rheumatoid arthritis is significantly more common in women than men and generally strikes when the patient is aged between 40 and 60.</li>
<li>Infectious arthritis: An infection in the synovial fluid and tissues of a joint. It is usually caused by bacterial, but could also be caused BY FUNGI or viruses.</li>
<li>Juvenile rheumatoid arthritis: Means arthritis that affects a person aged 16 or less. JRA can be a various form of arthritis ; it basically that a child has it .There are three main types;</li>
<li>Pauciarticular JRa</li>
<li>Polyarticular JRA</li>
<li>Systemic JRA</li>
</ul>
Signs and symptom
The symptom of arthritis depends on the type arthritis on the types of arthritis, for example;
<ul>
<li>Osteoarthritis: The symptoms develop slowly and get worse as time goes by .There is a pain in a joint, either during or after use or after a period of inactivity.</li>
<li>Rheumatoid arthritis: The patient often finds the same joint on each side of the body are painfully swollen, inflamed and stiff. The finger, arms, legs and wrist are most commonly affected.</li>
<li>Infectious arthritis: The patient has a fever joint inflammation and swelling. He will feel tenderness and \or a sharp pain.</li>
<li>Juvenile rheumatoid arthritis: The patient is a child .HE will experience intermittent fevers which tend to peak in the evening and then suddenly disappear.</li>
</ul>
Overall symptoms of arthritis: Arthritis causes joint pain , swelling , stiffness and limited movement. Symptoms can include:
<ul>
<li>Joint pain</li>
<li>Joint swelling</li>
<li>Reduced ability to move the joint</li>
<li>Reduced to the skin around a joint</li>
<li>Stiffness , especially in the morning</li>
<li>Warmth around a joint</li>
</ul>
Diagnosis
<ul>
<li>Medical History and Clinical symptoms: get medical history by having a list of current medication, medication allergies, the past and present medical history.</li>
<li>Physical Examination: Perform a physical examination to try to see any visible signs and symptoms that point to arthritis.</li>
<li>Redness\ Warmth</li>
<li>Joint stiffness</li>
<li>Swelling</li>
<li>Fever</li>
<li>Fatigue</li>
<li>Laboratory Tests: Blood test can provide more specific information and often server to confirm the diagnosis. Blood test is also used to monitor disease activity and treatment effectiveness after a diagnosis has been established:</li>
<li>Rheumatoid Factor</li>
<li>Erythrocyte Sedimentation Rate</li>
<li>C-reactive protein</li>
<li>Complete Blood Count</li>
<li>HLA Tissue Typing</li>
<li>Uric acid</li>
</ul>
Nursing care of patient with arthritis
<ul>
<li>Administer anti-inflammatory medication and other drugs as ordered.</li>
<li>Provide emotional support and reassurance to help the patient cope with limited mobility.</li>
<li>Encourage the patient to perform as much self-care as his immobility and pain allow</li>
<li>To help promote sleep, adjust pain medication that promotes to allow for maximum rest.</li>
<li>Help the patient identifies techniques and activities that promote rest and relaxation</li>
<li>Check crutches , cane , braces, or walker for proper fit</li>
<li>Assess the patient pain pattern.</li>
<li>Watch for skin irritation caused by prolonged use of assistive devices.</li>
<li>Instruct the patient to plan for adequate rest during the day.</li>
<li>Instruct the patient to take medication exactly as prescribed.</li>
</ul>

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Multielectron System

Multielectron system

Pauli's exclusion principle

According to this principle, '' No two electrons in an atom can have same values for the spin quantum number i.e.m_s.For example, in 1s orbital of the helium atom, there are two electrons. According to Pauli's exclusion principle, their quantum numbers are given below.

Electron: n l m m_s

1^stelectron 1 0 0 +\(\frac{1}{2}\)

2^ndelectron 1 0 0 -\(\frac{1}{2}\)

Thus the two electrons given above having the same values of n,land m but having different value of m_s.

This principle leads to very significant observation that ''Each orbital can accommodate at maximum two electrons with opposite spin''

The greatest use fo this principle is that it is helpful in determining themaximum number of electrons that main energy level have.

According to Pauli's exclusion principle, in a shell, there can only be two s and six p-electrons which are shown given below.

For s-orbital, l = 0 therefore allowed value of m = 0 and m_s= + \(\frac{1}{2}\) and resulting in only two electrons.

i,e, l = 0 m = 0, m_s= + \(\frac{1}{2}\) for first electron

m = 0, m_s= - \(\frac{1}{2}\) for second electron

Similarly, for p-sub shell, l = 1 allowed value of 'm' are -1. 0. +1 and allowed value of s for each value of m are + \(\frac{1}{2}\),m = 0, m_s= - \(\frac{1}{2}\) second electron

i. e. l =1 m = 1 s= + \(\frac{1}{2}\)

m = 1 s= - \(\frac{1}{2}\)

m = 0 s = + \(\frac{1}{2}\)

m = 0 s = - \(\frac{1}{2}\)

m = -1 s = + \(\frac{1}{2}\)

m = -1 s = - \(\frac{1}{2}\)

Six combinations given above show that p-sub shell conatains maximum six electrons.

Hund's rule of maximum multiplicity

This rule gives anidea about filling of anelectron in the orbital having equal energy. According to this rule ''Electrons are distributed among the orbitals of a subshell in such a way as to give the maximum number of unpaired electrons and have the same direction of spin''. The pairing of the electron will start after all the orbitals of a given sub-level are singly occupied.

Let us take an example in which three electrons are to be filled in p-orbitals. There can be two possibilities.

\(\upharpoonleft\) \(\downharpoonright\)

\(\upharpoonleft\)

Incorrect (I)

\(\upharpoonleft\)

Correct (II)

According to this rule, filling of electrons in which each orbital is singly occupied i.e. arrangement (II) is correct.

For example in the ground state for Nitrogen, the electronic configuration, and orbital arrangement is as follows:- 1s²2s²2p³

Aufbau Principle or (n+l) rule

Aufbau principle is also known as building up principle. According to this principle "In the ground state of an atom electrons are arranged that they occupy the orbitals in order of their increasing energy". Thus, the orbital with the lowest energy will be filled first and then next higher energy and so on.

Since the energy of an orbital is determined by the quantum numbers 'n' and 'l', the correct sequence of filling of the orbitals proceed on the basis of following two rules called (n+l) rule.

The orbitals having lowest value of (n+l) are occupied first by eletron. eg. 4s orbital is filled before 3d.

4s = (n+l) = 4 + 0 = 4 3d = (n + l) = 3 + 2 = 5

It is because 4s has lowest value of (n + l ) than 3d

2. When two orbitals have the same values of ( n + l ), the orbital having lower value of n is filled up first. For example in case of 2p

and 3s orbitals the (n + l ) value are same i.e. 3 in both but 2p orbital is filled before 3s because 2p has lower value of n.

Limitation of Aufbau Principle

Aufbau Principle does not tell us which electrons are to be removed when an ion is formed from an atom.

For example, electronic configuration of Fe = [Ar] 4s²3d⁶

electronic configuration of Fe²⁺= [Ar] 3d⁶

Here, 4s subshell is filled prior to 3d but on ionization, 4s electron is removed which is contrary of Aufbau order of filling.

2. Elements with atomic number 24 (Cr), 29 (Cu) etc have shown little deviation from Aufbau principle. According to Aufbau, electronic

configuration fo Cr is [Ar] 3d⁹4s²but the experimentally supported configuration is [Ar] 3d⁵4s¹is experimentally observed configuration of Cu. The reason for the deviation lies in extra stability associated with half filled or completely filled subshells.

Reasons for the extra stability of half filled and completely filled subshell

Stability on the basis of the symmetrical distribution of electrons: Completely filled or exactly half filled orbitals are more stable because of symmetrical distribution of electrons.

For example, the atomic number of Chromium is 24. The electronic configuration should be 3d⁴4s²

\(\upharpoonleft\)

3d⁴

\(\upharpoonleft\) \(\downharpoonright\)

4s²

But the actual electronic configuration is 3d⁵4s¹

3d⁵

\(\upharpoonleft\)

4s¹

\(\upharpoonleft\)

2. Stability due to exchange energy: The half filled and completely filled electronic configuration are stable due to large exchange energy of stabilization. The exchange means the shifting of electrons from one orbital to another in the same subshell.

Example In Cr and in 3d⁴arrnagement, electrons can exchange in 6 ways.On the other hand in 3d⁵configuration, the electron can exchange in10 ways. Since the number of exchanges in 3d⁵4s¹configuration is more than in 3d⁴4s² configuration, therefore the greater exchange is responsible for the extra stability of this configuration. Also, there is more configuration possible for d¹⁰than d⁹.

References

chemwiki. n.d. <chemwiki.ucdavis.edu › ... › Electronic Configurations>.

Lee, J.D. Concise Inorganic Chemistry. John Wiley and sons.Inc, 2007.

Wikipedia. n.d. <https://en.wikipedia.org/wiki/Aufbau_principle>.

WOW. n.d. <www.wow.com/wiki/Hund's_rule_of_maximum_multiplicity>.

Lesson

Multi-electron System

Subject

Chemistry

Grade

Bachelor of Science

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