(i) Explain the factors influencing the ionisation energies of elements

Einstein Academy

19 Apr 202020:35

EducationalLearning

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TLDRThis Einstein Academy video delves into the factors influencing ionization energies of elements, a key learning outcome from the JCH to Chemistry syllabus. It explains ionization energy as the energy required to remove an electron from an atom, highlighting that it's a positive, endothermic process. The video discusses how the size of the nuclear charge, atomic radius, and screening effect impact ionization energies, noting anomalies in trends across periods and down groups. It also emphasizes the concept of effective nuclear charge and its role in determining ionization energy variations among elements.

Takeaways

🔬 Ionization energy is the energy required to remove one electron from each atom or ion in a mole of gaseous atoms or ions to form a gaseous cation.
📈 The first ionization energy is the energy needed to remove the first electron from an atom, and subsequent ionization energies are progressively higher due to the stronger attraction of the remaining electrons to the nucleus.
💡 Ionization energies are positive values, indicating that energy is absorbed in the process, as electrons are attracted to the nucleus and must be overcome.
⚛️ Factors influencing ionization energies include the size of the positive nuclear charge, atomic and ionic radius, and the screening effect.
🌐 The effective nuclear charge is a measure of how strongly the nucleus attracts the outermost electrons, taking into account the three influencing factors.
📊 Ionization energy generally increases across a period (row) in the periodic table due to an increase in the number of protons and a relatively constant screening effect.
🔍 Anomalies in the trend of ionization energy across a period include boron having a lower ionization energy than beryllium and oxygen having a lower ionization energy than nitrogen, due to the stability of half-filled orbitals and electron repulsion.
📉 Ionization energy generally decreases down a group in the periodic table as the screening effect increases due to more electron shells and the distance between the nucleus and valence electrons increases.
📚 Understanding the electronic configuration of elements helps explain anomalies in ionization energy trends, as the stability of certain configurations affects the energy required to remove an electron.
🌟 The lecture aims to clarify the concept of ionization energy, its trends, and the factors influencing these trends, preparing students for further study and examination questions on the topic.
👋 The video concludes with an invitation for viewers to like, subscribe, and join future lectures by Einstein Academy for more in-depth exploration of chemistry topics.

Q & A

What is ionization energy?
-Ionization energy is the amount of energy required to remove one electron from each atom or ion in a mole of gaseous atoms or ions, producing one more gaseous cation.
Why is the ionization energy generally a positive value?
-The ionization energy is positive because energy must be supplied to overcome the electrostatic attraction between the electron and the positively charged nucleus.
How does the ionization energy of an element compare to its successive ionization energies?
-Successive ionization energies are usually larger than the previous one because the remaining electrons are more strongly attracted to the same number of positive charges in the nucleus.
What are the three factors that influence ionization energies?
-The three factors influencing ionization energies are the size of the positive nuclear charge, atomic and ionic radius, and the screening effect.
How does the size of the positive nuclear charge affect ionization energy?
-An increase in the size of the positive nuclear charge results in a stronger attraction of the valence electron to the nucleus, which in turn requires more energy to remove the electron, thus increasing the ionization energy.
What is the relationship between atomic radius and ionization energy?
-As the atomic radius increases, the distance between the nucleus and the valence electron also increases, leading to a weaker attraction and consequently a decrease in ionization energy.
Can you explain the screening effect and its impact on ionization energy?
-The screening effect is when inner electrons shield the valence electron from the attraction of the nucleus. A higher screening effect means the outermost electron is less strongly attracted to the nucleus, requiring less energy to remove it, and thus decreasing the ionization energy.
What is meant by effective nuclear charge and how does it relate to ionization energy?
-Effective nuclear charge refers to how effectively the nucleus attracts electrons, taking into account the factors that influence ionization energy. A higher effective nuclear charge results in a greater ionization energy because the nucleus is more effective in attracting the electron.
How does the ionization energy trend across a period in the periodic table?
-Generally, ionization energy increases across a period due to an increase in the number of protons and a relatively constant screening effect, leading to a stronger effective nuclear charge.
What are the two anomalies in the trend of ionization energy across a period mentioned in the script?
-The two anomalies are that the ionization energy of boron is lower than that of beryllium, and the ionization energy of oxygen is lower than that of nitrogen, due to differences in electron configuration and the nature of electron removal.
Why does ionization energy generally decrease down a group in the periodic table?
-Ionization energy decreases down a group due to an increase in the screening effect from additional electron shells and an increase in the distance between the nucleus and the valence electrons, which reduces the effective nuclear charge.

Outlines

00:00

🔬 Understanding Ionization Energy

The first paragraph introduces the concept of ionization energy, which is the energy required to remove an electron from an atom or ion, resulting in a cation. It explains that ionization energy is a positive value because energy is needed to overcome the electrostatic attraction between the electron and the nucleus. The paragraph uses the example of sodium and magnesium to illustrate how ionization energy increases with each successive electron removed, due to the stronger attraction of remaining electrons to the nucleus in a positively charged ion.

05:02

🔍 Factors Influencing Ionization Energies

The second paragraph delves into the factors that affect ionization energies, which include the size of the positive nuclear charge, atomic and ionic radius, and the screening effect. It explains how an increase in nuclear charge leads to a stronger attraction and thus higher ionization energy. Conversely, a larger atomic radius results in a weaker attraction and lower ionization energy. The screening effect is described as inner electrons reducing the effective attraction between the nucleus and the valence electrons, leading to lower ionization energy with more inner electrons.

10:05

📊 Trends in Ionization Energy Across the Periodic Table

The third paragraph discusses the trends in ionization energy as a function of atomic number, noting the general increase in ionization energy across a period due to increasing nuclear charge and relatively constant screening effect. It also addresses the anomalies where ionization energy decreases for certain elements, such as boron compared to beryllium and oxygen compared to nitrogen, and attributes these to the specific electronic configurations and the stability of the resulting ions.

15:09

📉 Variation of Ionization Energy Down a Group

The fourth paragraph explains the decrease in ionization energy down a group in the periodic table. It attributes this to the increasing number of electron shells, which enhances the screening effect, and the increasing distance between the nucleus and the valence electrons, which weakens the effective nuclear charge. The overall effect is a decrease in ionization energy, despite the increase in nuclear charge due to additional protons.

20:09

📚 Conclusion and Future Learning Outcomes

The final paragraph summarizes the lecture on ionization energies and teases upcoming content, including further learning outcomes and passive A-level questions related to the topic. It invites viewers to like and subscribe for more educational content from Einstein Academy, signaling the end of the current discussion on ionization energies.

Mindmap

Keywords

💡Ionization Energy

Ionization energy is defined as the amount of energy required to remove one electron from each atom or ion in a mole of gaseous atoms or ions, producing one more gaseous cation. It is central to the video's theme as it is the primary concept being explained. The video script uses the term to describe the energy needed for an electron to overcome the attractive force of the nucleus, as seen in the chemical equation for sodium where the first ionization energy is +496 kilojoules per mole.

💡Gaseous

The term 'gaseous' refers to the state of matter in the form of a gas. In the context of the video, it is important because ionization energy specifically pertains to gaseous atoms or ions. The script emphasizes the state of the atoms in the chemical equation that defines ionization energy, indicating that the state of matter affects the energy required for ionization.

💡First Ionization Energy

First ionization energy is the energy required to remove the first electron from a neutral atom, forming a cation with a +1 charge. The video script explains this concept by using magnesium as an example, where the first ionization energy is +78 kilojoules per mole, highlighting the process of ionization and the energy involved in the initial electron removal.

💡Second Ionization Energy

Second ionization energy is the energy needed to remove an electron from a cation that already has a +1 charge, resulting in a cation with a +2 charge. The video script discusses this by comparing the ionization energies of magnesium, noting that the second ionization energy is higher than the first, illustrating the increasing energy requirement for successive electron removals.

💡Effective Nuclear Charge

Effective nuclear charge is a concept that describes how effectively the nucleus of an atom attracts the outermost electrons, taking into account the shielding effect of inner electrons. The video script introduces this term to explain the variations in ionization energy across different elements, emphasizing that a higher effective nuclear charge results in a stronger attraction and thus higher ionization energy.

💡Atomic Radius

Atomic radius refers to the distance from the nucleus to the outermost shell of an atom. The video script explains that as the atomic radius increases, the attraction between the nucleus and the valence electrons decreases because they are further apart, leading to a lower ionization energy. This concept is key to understanding how the size of an atom influences its ionization energy.

💡Screening Effect

The screening effect is the phenomenon where inner electrons shield the outermost electrons from the full attractive force of the nucleus. The video script uses this concept to explain why elements with more inner electrons have a lower ionization energy, as the outer electrons are less strongly attracted to the nucleus due to the increased shielding.

💡Periodic Trends

Periodic trends refer to the patterns observed in the properties of elements as they are arranged in the periodic table. The video script discusses how ionization energy generally increases across a period and decreases down a group, providing examples of anomalies such as boron having a lower ionization energy than beryllium, which is explained by the different electron configurations and the associated energy levels.

💡Electronic Configuration

Electronic configuration describes the distribution of electrons in an atom's orbitals. The video script uses the term to explain the anomalies in ionization energy trends, such as why oxygen has a lower first ionization energy than nitrogen, by examining the arrangement of electrons in the 2p orbitals and the associated stability and repulsion effects.

💡Anomalies

In the context of the video, anomalies refer to exceptions to the general trend of ionization energies across the periodic table. The script provides specific examples, such as boron having a lower ionization energy than beryllium and oxygen having a lower ionization energy than nitrogen, and explains these anomalies based on the unique electronic configurations and the nature of the orbitals from which electrons are removed.

Highlights

Explaining the factors influencing the ionization energies of elements according to the JCH to Chemistry syllabus.

Defining ionization energy as the energy required to remove one electron from each atom or ion in a mole of gaseous atoms or ions.

The ionization energy is a positive value because energy is needed to overcome the attraction between the nucleus and the electron.

Successive ionization energies increase due to a stronger attraction of the remaining electrons to the unchanged positive charges in the nucleus.

The ionization energy of magnesium is lower than that of sodium due to the increased screening effect and larger atomic radius.

Three main factors influencing ionization energy: size of the positive nuclear charge, atomic and ionic radius, and the screening effect.

Effective nuclear charge increases ionization energy as it describes the attraction between the nucleus and the outermost electron.

Ionization energy generally increases across a period due to an increase in the effective nuclear charge.

Anomalies in ionization energy trends: Boron has a lower ionization energy than Beryllium, and Oxygen has a lower ionization energy than Nitrogen.

The lower ionization energy of Boron is attributed to the removal of a 2p electron which is further from the nucleus.

Oxygen's lower ionization energy compared to Nitrogen is due to the removal of a paired 2p electron experiencing greater repulsion.

Ionization energy decreases down a group due to an increase in the screening effect and the distance between the nucleus and valence electron.

The overall effect of factors on ionization energy down a group is a decrease in the effective nuclear charge.

A graph illustrating ionization energy as a function of atomic number, showing trends and anomalies.

Understanding the electronic configuration is crucial for explaining anomalies in ionization energy trends.

The lecture aims to clarify the factors influencing ionization energies and their application in understanding atomic structure.

Upcoming lectures will cover further learning outcomes and A-level questions related to ionization energies.

Transcripts

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