ENERGIA DE IONIZACION. Con ejercicios y ejemplos. Propiedades periodicas
Understanding Ionization Energy
Introduction to Periodic Properties
- The lesson begins with a warm welcome to students, emphasizing the ease of learning new chemistry concepts.
- Focus is on ionization energy as a periodic property, which varies based on an element's position in the periodic table.
Definition of Ionization Energy
- Ionization energy is defined as the energy required to remove the outermost electron from a neutral atom, converting it into a cation (positively charged ion).
- Example provided using lithium (atomic number 3), illustrating that a neutral lithium atom has three protons and three electrons.
Electron Configuration and Removal Process
- The discussion highlights that removing the outermost electron requires overcoming its attraction to the nucleus due to opposite charges.
- Lithium's electronic configuration shows two electrons in the first level and one in the second; this outer electron is easier to remove.
Changes Post-Ionization
- Once an electron is removed, lithium becomes a cation with three protons and only two electrons, resulting in a net positive charge.
- This process illustrates why ionization energy is crucial for understanding atomic behavior and properties.
Trends in Ionization Energy Across Groups and Periods
- In groups (vertical columns), ionization energy increases from bottom to top; atoms higher up require more energy to remove an electron.
- In periods (horizontal rows), ionization energy increases from left to right; atoms further right have higher ionization energies due to increased nuclear charge.
Explanation of Group Trends
- Atoms lower in groups have more energy levels, making their outer electrons farther from the nucleus and easier to remove.
- Comparison between hydrogen, lithium, and sodium illustrates how additional energy levels affect electron removal difficulty.
Explanation of Period Trends
Understanding Ionization Energy and Periodic Trends
The Relationship Between Atomic Structure and Ionization Energy
- The atomic structure of lithium, beryllium, and boron is discussed, highlighting that lithium has three protons, beryllium four, and boron five. This indicates that boron's effective nuclear charge is greater than that of lithium.
- Due to the higher effective nuclear charge in boron, its electrons are drawn closer to the nucleus. Consequently, this results in a smaller atomic size for boron compared to lithium.
- It becomes more challenging to remove an electron from boron than from lithium because the electrons are held more tightly by the nucleus. Thus, more ionization energy is required for boron.
Trends in Ionization Energy Across the Periodic Table
- The discussion shifts to comparing ionization energies between hydrogen and potassium. Since ionization energy increases as you move up the periodic table, hydrogen possesses a higher ionization energy than potassium.
- A comparison between boron and fluorine reveals that fluorine has a greater ionization energy than both boron and carbon due to its position on the periodic table where ionization energy increases across periods.
Conclusion on Ionization Energy Trends