Valence Electrons and Groups
🔬 Part 1: Understanding Valence Electrons
1. What are valence electrons?
Electrons in the innermost shell
Electrons in the outermost shell
Electrons that move between atoms
Electrons in the nucleus
2. Why are valence electrons important in chemistry? (Short answer)
3. Fill in the blanks:
Valence electrons determine how atoms __________ with each other. Elements in the same group have the same number of __________ electrons, which gives them similar __________ properties.
📊 Part 2: Groups and Valence Electrons
4. How many valence electrons do elements in Group 1 have?
5. Match each group with its number of valence electrons:
1. Group 1 (Alkali metals)
2. Group 2 (Alkaline earth metals)
3. Group 17 (Halogens)
4. Group 18 (Noble gases)
A. 8 valence electrons (except He)
B. 1 valence electron
C. 7 valence electrons
D. 2 valence electrons
6. Which of these elements have the same number of valence electrons? (Check all that apply)
Sodium (Na) and Potassium (K)
Chlorine (Cl) and Fluorine (F)
Carbon (C) and Silicon (Si)
Helium (He) and Neon (Ne)
⚛️ Part 3: Electron Shell Diagrams
7. Draw the electron shell diagram for Lithium (Li) - Atomic number 3:
8. Draw the electron shell diagram for Chlorine (Cl) - Atomic number 17:
9. How many valence electrons does each element have?
a) Oxygen (O): ______ valence electrons
b) Magnesium (Mg): ______ valence electrons
c) Aluminium (Al): ______ valence electrons
d) Sulfur (S): ______ valence electrons
🧪 Part 4: Chemical Properties and Reactivity
10. Why do elements in the same group have similar chemical properties?
11. Which group is the most unreactive and why?
Group 1 - they have only 1 valence electron
Group 17 - they need only 1 more electron
Group 18 - they have full outer shells
Group 2 - they have 2 valence electrons
12. Predict the properties: If an unknown element is in Group 1, what properties would you expect it to have? (Check all that apply)
Highly reactive with water
Forms ionic compounds easily
Unreactive under normal conditions
Loses electrons easily
Metallic properties
🎯 Part 5: Challenge Questions
13. Extension: Explain why sodium (Na) and chlorine (Cl) react so readily with each other. Use your knowledge of valence electrons in your answer.
14. Research task: Find three elements from Group 14 and write their names and symbols below. How many valence electrons do they each have?
15. Critical thinking: Why do you think the periodic table is organised into groups? How does this organisation help scientists?
