Lesson: Periodic Trends - Mixed Practice Ranking

Introduction

In this lesson, we will explore various periodic trends, focusing on ranking elements based on their properties. Understanding these trends helps predict the behavior of elements in chemical reactions.

Key Concepts

1. Atomic Radius: The distance from the nucleus to the outermost electrons. It generally increases down a group and decreases across a period due to increased nuclear charge.
2. Ionization Energy (IE): The energy required to remove an electron from an atom in the gas phase. It increases across a period and decreases down a group.
   • $IE$ = $\frac{{E}_{final} - {E}_{initial}}{n}$ where ${E}_{final}$ is the energy after removing an electron, and ${E}_{initial}} is the energy of the neutral atom.
3. Electronegativity: The tendency of an atom to att\fract electrons in a bond. It increases across a period and decreases down a group.
4. Electron Affinity (EA): The energy change when an electron is added to a neutral atom. It generally becomes more negative across a period.

Mixed Practice Ranking

Rank the following elements based on the provided property:

• Elements: Sodium $Na$, Magnesium $Mg$, Aluminum $Al$

• Property: Ionization Energy

  • Ranking: $Mg > Al > Na$

• Elements: Chlorine $Cl$, Fluorine $F$, Iodine $I$

• Property: Electronegativity

  • Ranking: $F > Cl > I$

• Elements: Lithium (Li), Potassium (K), Rubidium (Rb)

• Property: Atomic Radius

  • Ranking: $Rb > K > Li$

Key Questions

• How does the atomic radius change across a period and down a group?
• What factors influence ionization energy and electronegativity?
• Why do elements in the same group have similar chemical properties?

Conclusion

Understanding periodic trends allows for effective predictions of element behavior in reactions, which is crucial for mastering chemistry concepts.