Physical Science Matric Revision: Periodic Table

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Revision Notes: Periodic Table – CAPS Grade 12 Physical Sciences

1. Introduction

Understanding the Periodic Table is crucial in the study of Chemistry. It organizes all known elements based on their properties and atomic structure. This helps predict the behavior of elements and their compounds. Key learning objectives include understanding element classification, periodic trends, and the significance of element groups.

2. Key Points

  • Periodic Table Structure:
  • Elements are arranged by increasing atomic number.
  • Rows are called periods and columns are called groups.

  • Elements in the same group have similar chemical properties.

  • Groups and Periods:

  • Groups: Vertical columns (18 in total).

  • Periods: Horizontal rows (7 in total).

  • Element Categories:

  • Metals: Typically found on the left side.
  • Non-metals: Right side.

  • Metalloids: Elements with properties of both metals and non-metals, located between metals and non-metals.

  • Key Groups:

  • Alkali Metals (Group 1): Highly reactive, especially with water (e.g., Sodium, Potassium).
  • Alkaline Earth Metals (Group 2): Less reactive than alkali metals (e.g., Magnesium, Calcium).
  • Halogens (Group 17): Very reactive non-metals (e.g., Fluorine, Chlorine).

  • Noble Gases (Group 18): Inert gases, unreactive (e.g., Helium, Neon).

  • Periodic Trends:

  • Atomic Radius: Decreases across a period, increases down a group.
  • Ionization Energy: Increases across a period, decreases down a group.
  • Electron Affinity: Generally increases across a period.
  • Electronegativity: Increases across a period, decreases down a group.

3. Real-World Applications

  • Industry: Elements like Iron (Fe) and Copper (Cu) are used in construction and electrical wiring respectively.
  • Medicine: Elements such as Iodine (I) are used in disinfectants and thyroid medication.
  • Technology: Silicon (Si) is crucial for manufacturing electronic devices.

Example Problem:
Calculate the change in atomic radius between Sodium (Na) and Chlorine (Cl).

Solution:
– Sodium has a larger atomic radius due to its position in Group 1 and Period 3.
– Chlorine, positioned further right in the same period, has a smaller atomic radius due to the increased nuclear charge pulling electrons closer.

4. Common Misconceptions and Errors

  • Confusing Groups and Periods: Remember groups are vertical columns, and periods are horizontal rows.
  • Reactivity Trends: Metals generally increase in reactivity down a group, whereas non-metals decrease.
  • Stable Noble Gases: Due to their full valence electron shells, noble gases are often mistakenly thought to readily form compounds.

5. Practice and Review

Questions

  1. Classify the following elements as metals, non-metals, or metalloids: Silicon (Si), Fluorine (F), Iron (Fe).
  2. Predict the reactivity between elements in Group 1 versus Group 17.
  3. Explain why ionization energy increases across a period.

Answers

  1. Silicon (Metalloid), Fluorine (Non-metal), Iron (Metal).
  2. Group 1 elements (e.g., Sodium) are highly reactive metals; Group 17 elements (e.g., Chlorine) are highly reactive non-metals.
  3. Ionization energy increases because of a greater effective nuclear charge across a period, making it harder to remove electrons.

6. Connections and Extensions

  • Interdisciplinary Links:
  • Physics: Understanding electron configurations and atomic structure.

  • Biology: Role of trace elements in physiological processes.

  • Real-World Implications:

  • Predicting element behavior in compounds aids in fields like pharmacology and material science.

7. Summary and Quick Review

  • Elements are organized by atomic number.
  • Groups share similar properties.
  • Trends: Atomic radius, ionization energy, electron affinity, and electronegativity vary predictably across the table.

8. Additional Resources

By mastering these points, you will be well-prepared for any questions on the periodic table in your final exams. Good luck!