Assessment Criteria & Mark Allocation (Total: 20 marks)

This rubric outlines the assessment criteria and mark allocation for the Year 11 Science assessment on atomic structure and bonding.

Marking Schedule Breakdown

• 4 questions × 1 mark each

• Topics: Atomic number, mass number, basic bonding identification

• Mark allocation: 1 mark for correct answer, 0 marks for incorrect

• Correct Answers:

• 1. Atomic Number: Number of protons in an atom.
• 2. Mass Number: Total number of protons and neutrons in an atom.
• 3. Ionic Bonding: Transfer of electrons between atoms.
• 4. Covalent Bonding: Sharing of electrons between atoms.

• Define atomic number (1 mark), mass number (1 mark), ionic bonding (1 mark), covalent bonding (1 mark)

• Mark allocation: 1 mark for accurate definition including key scientific terms

• 0.5 marks for partially correct definition missing key elements

• Correct Answers:

• Atomic Number: The number of protons in the nucleus of an atom, which determines the element's identity.
• Mass Number: The sum of protons and neutrons in the nucleus of an atom.
• Ionic Bonding: A type of chemical bond formed through the electrostatic attraction between oppositely charged ions.
• Covalent Bonding: A type of chemical bond where two atoms share one or more pairs of electrons.

• Draw Bohr model for given element (e.g., Carbon-12)

• Mark allocation:

  - Correct nucleus representation (1 mark)

  - Accurate electron shells/energy levels (2 marks)

  - Correct electron distribution (2 marks)

  - Proper labelling of components (1 mark)

• Correct Answer:

• Bohr model for Carbon-12: 6 protons and 6 neutrons in the nucleus, 2 electrons in the first shell, and 4 electrons in the second shell.

• Explain formation of one ionic and one covalent compound

• Mark allocation:

  - Ionic bonding explanation (3 marks): electron transfer (1), charge formation (1), attraction forces (1)

  - Covalent bonding explanation (3 marks): electron sharing (1), bond formation (1), molecular structure (1)

• Correct Answers:

• Ionic Bonding Example: Sodium Chloride (NaCl) - Sodium (Na) loses one electron to become Na⁺, and Chlorine (Cl) gains that electron to become Cl^-, resulting in an ionic bond due to the electrostatic attraction between Na⁺ and Cl^-.
• Covalent Bonding Example: Water (H₂O) - Two hydrogen atoms share electrons with one oxygen atom, forming covalent bonds and creating a bent molecular structure.

 Assessment Guidelines

• Award marks for scientifically accurate content even if expressed in student's own words

• Deduct 0.5 marks for significant spelling errors in scientific terminology

• Partial marks available for incomplete but correct working in diagram questions

• No penalty for minor drawing imperfections if scientific accuracy maintained

Excellence (18-20 marks): Comprehensive understanding, accurate application, excellent diagrams

Merit (14-17 marks): Good understanding with minor gaps, mostly accurate work

Achieved (10-13 marks): Basic understanding, some correct applications, adequate diagrams

Not Achieved (0-9 marks): Limited understanding, significant errors, poor diagram quality