📚 WALT & Success Criteria

WALT: Describe the structure of atoms and identify subatomic particles

Success Criteria:

• All students: Identify protons, neutrons and electrons in atoms

• Most students: Calculate numbers of subatomic particles using atomic and mass numbers

• Some students: Explain how electron arrangement affects chemical properties

🔬 Part 1: Atomic Structure Model (POGIL Activity)

Teacher Answer:

Proton: Charge = +1, Mass = 1, Location = Nucleus

Neutron: Charge = 0, Mass = 1, Location = Nucleus

Electron: Charge = -1, Mass = 1/1836 (negligible), Location = Electron shells

Teacher Answer:

Atomic number = 6 (number of protons)

Mass number = 12

Number of protons = 6

Number of neutrons = 12 - 6 = 6

Number of electrons = 6 (neutral atom)

⚛️ Part 2: Electron Arrangement & Chemical Properties

Teacher Answers:

Sodium (Na, atomic number 11): 2,8,1

Chlorine (Cl, atomic number 17): 2,8,7

Argon (Ar, atomic number 18): 2,8,8

Teacher Answers:

Carbon-14: 6 protons, 8 neutrons, 6 electrons

Uranium-235: 92 protons, 143 neutrons, 92 electrons

Hydrogen-2 (deuterium): 1 proton, 1 neutron, 1 electron

📋 Teacher Notes & Differentiation

Differentiation Strategies:

• Support: Provide periodic table and electron shell diagrams

• Core: Use scaffolded calculations with worked examples

• Extension: Include isotope calculations and ion formation

Common Misconceptions to Address:

• Electrons do not orbit the nucleus like planets

• Mass number is NOT the same as atomic number

• Isotopes have different mass numbers but same atomic number

Assessment Opportunities:

• Peer assessment of electron configurations

• Mini-whiteboards for quick checks

• Exit ticket: "Explain why helium is unreactive"