Basics of Chemical Combinations and Electronic Configurations Chemistry SS 1 First Term Lesson Notes Week 7

Chemistry SS 1 First Term Lesson Notes – Week 7

Subject: Chemistry
Class: SS 1
Term: First Term
Week: 7
Age: 14-16 years
Topic: Chemical Combinations I
Sub-Topics:

1. Periodic Table (First 20 Elements)
2. Electronic Configuration of Atoms

Duration: 40 minutes

Behavioral Objectives:

By the end of the lesson, students should be able to:

1. List and identify the first 20 elements of the periodic table.
2. Understand the significance of the periodic table in chemistry.
3. Explain the concept of electronic configuration.
4. Write the electronic configurations for the first 20 elements.
5. Relate the electronic configuration of an atom to its position in the periodic table.

Keywords: Periodic table, elements, electronic configuration, atomic structure.

Content

1. Periodic Table (First 20 Elements)

• Explanation: The periodic table organizes elements based on their atomic number and properties. The first 20 elements include:
  1. Hydrogen (H)
  2. Helium (He)
  3. Lithium (Li)
  4. Beryllium (Be)
  5. Boron (B)
  6. Carbon (C)
  7. Nitrogen (N)
  8. Oxygen (O)
  9. Fluorine (F)
  10. Neon (Ne)
  11. Sodium (Na)
  12. Magnesium (Mg)
  13. Aluminum (Al)
  14. Silicon (Si)
  15. Phosphorus (P)
  16. Sulfur (S)
  17. Chlorine (Cl)
  18. Argon (Ar)
  19. Potassium (K)
  20. Calcium (Ca)
• Significance: The periodic table allows scientists to predict the properties of elements and how they interact with one another.

2. Electronic Configuration of Atoms

• Explanation: Electronic configuration describes the arrangement of electrons in an atom’s shells. The distribution follows the principles of the Aufbau principle, Pauli exclusion principle, and Hund’s rule.
• Electronic Configurations for the First 20 Elements:
  1. H: 1s¹
  2. He: 1s²
  3. Li: [He] 2s¹
  4. Be: [He] 2s²
  5. B: [He] 2s² 2p¹
  6. C: [He] 2s² 2p²
  7. N: [He] 2s² 2p³
  8. O: [He] 2s² 2p⁴
  9. F: [He] 2s² 2p⁵
  10. Ne: [He] 2s² 2p⁶
  11. Na: [Ne] 3s¹
  12. Mg: [Ne] 3s²
  13. Al: [Ne] 3s² 3p¹
  14. Si: [Ne] 3s² 3p²
  15. P: [Ne] 3s² 3p³
  16. S: [Ne] 3s² 3p⁴
  17. Cl: [Ne] 3s² 3p⁵
  18. Ar: [Ne] 3s² 3p⁶
  19. K: [Ar] 4s¹
  20. Ca: [Ar] 4s²

Evaluation Questions (15 Fill-in-the-Blank Questions with Multiple Choice Options)

1. The first element in the periodic table is __________.
   • a) Helium
   • b) Hydrogen
   • c) Lithium
   • d) Beryllium
     Answer: b) Hydrogen
2. The chemical symbol for Sodium is __________.
   • a) S
   • b) Na
   • c) So
   • d) Sd
     Answer: b) Na
3. The electronic configuration of Oxygen is __________.
   • a) 1s² 2s² 2p⁴
   • b) 1s² 2s² 2p⁶
   • c) 1s² 2s²
   • d) 1s² 2s² 2p³
     Answer: a) 1s² 2s² 2p⁴
4. The atomic number of Carbon is __________.
   • a) 6
   • b) 12
   • c) 14
   • d) 8
     Answer: a) 6
5. In the periodic table, elements are arranged by their __________.
   • a) mass
   • b) atomic number
   • c) chemical properties
   • d) density
     Answer: b) atomic number
6. The electronic configuration of Neon is __________.
   • a) [He] 2s² 2p⁴
   • b) [He] 2s² 2p⁶
   • c) 1s² 2s²
   • d) [He] 2s¹
     Answer: b) [He] 2s² 2p⁶
7. Which of the following elements has the electronic configuration of [Ne] 3s² 3p⁴?
   • a) Sodium
   • b) Silicon
   • c) Sulfur
   • d) Argon
     Answer: c) Sulfur
8. The periodic table consists of __________ main groups of elements.
   • a) 6
   • b) 8
   • c) 18
   • d) 20
     Answer: c) 18
9. The element with the symbol Cl is __________.
   • a) Chlorine
   • b) Calcium
   • c) Carbon
   • d) Chromium
     Answer: a) Chlorine
10. The electronic configuration of Potassium is __________.
    • a) [Ar] 4s²
    • b) [Ne] 3s² 3p¹
    • c) [Ar] 4s¹
    • d) [Ne] 3s²
      Answer: c) [Ar] 4s¹
11. The chemical symbol for Argon is __________.
    • a) Ar
    • b) Ag
    • c) Au
    • d) Al
      Answer: a) Ar
12. The electronic configuration for Lithium is __________.
    • a) 1s² 2s¹
    • b) [He] 2s¹
    • c) 1s² 2p¹
    • d) [H] 1s¹
      Answer: b) [He] 2s¹
13. The atomic number of Calcium is __________.
    • a) 20
    • b) 12
    • c) 14
    • d) 16
      Answer: a) 20
14. The group of elements that are gases at room temperature include __________.
    • a) Metals
    • b) Nonmetals
    • c) Metalloids
    • d) Transition metals
      Answer: b) Nonmetals
15. The first 20 elements of the periodic table represent the __________ of all known elements.
    • a) most abundant
    • b) essential
    • c) simplest
    • d) complex
      Answer: c) simplest

Class Activity Discussion (15 FAQs with Answers)

1. What is the periodic table?
   It is an organized chart of elements arranged by atomic number and properties.
2. Why are the first 20 elements significant?
   They represent the simplest and most commonly encountered elements in chemistry.
3. What does electronic configuration mean?
   It describes the arrangement of electrons in an atom’s shells.
4. How is the periodic table structured?
   Elements are arranged in rows (periods) and columns (groups) based on similar properties.
5. What is the atomic number?
   It is the number of protons in the nucleus of an atom, which determines the element’s identity.
6. How do you determine the electronic configuration for an element?
   By following the Aufbau principle and noting the number of electrons.
7. What is the significance of knowing an element’s electronic configuration?
   It helps predict an element’s chemical behavior and reactivity.
8. Are there any exceptions in electronic configurations?
   Yes, some elements have irregular configurations due to stability factors.
9. How does the position of an element in the periodic table relate to its properties?
   Elements in the same group have similar chemical properties due to their valence electron configurations.
10. What are valence electrons?
    They are the electrons in the outermost shell that are involved in chemical bonding.
11. Why is hydrogen placed at the top of the periodic table?
    Because it has the atomic number 1 and exhibits unique properties.
12. What element is represented by the symbol He?
    Helium.
13. Can electronic configurations be used to identify elements?
    Yes, each element has a unique electronic configuration.
14. What does the term “noble gas configuration” refer to?
    It describes the stable electronic arrangement found in the noble gases.
15. How do you write an element’s symbol?
    The first letter is always capitalized, and the second (if any) is lowercase.

Evaluation Questions (10 Questions)

1. What is the significance of the periodic table?
   • Answer: It organizes elements based on their properties and atomic number.
2. How many elements are in the first 20 of the periodic table?
   • Answer: 20 elements.
3. Which element has the atomic number 8?
   • Answer: Oxygen.
4. Write the electronic configuration for Nitrogen.
   • Answer: 1s² 2s² 2p³.
5. What is the chemical symbol for Magnesium?
   • Answer: Mg.
6. Describe the relationship between an element’s position and its electronic configuration.
   • Answer: The position indicates the number of electrons and their arrangement.
7. Identify the element with the electronic configuration [Ne] 3s² 3p⁵.
   • Answer: Chlorine.
8. What is the electron configuration for an element with an atomic number of 12?
   • Answer: 1s² 2s² 2p⁶ 3s².
9. What group of elements includes nonmetals?
   • Answer: Groups 14-18 (or group 17 for halogens).
10. Explain why some elements may not follow the typical electronic configuration rules.
    • Answer: Due to stability and energy considerations, some elements exhibit exceptions.