Expert Chemistry Tutoring

MS1. Knowledge Recall (1 mark)

- Sharing of electrons between two or more atoms (1 mark)

MS2. Application of knowledge (2 marks)

- Weak forces between covalent molecules (1 mark)

- Little energy needed to overcome these forces (1 mark)

MS3. Knowledge Recall (2 marks)

- Single covalent: H2, molecules with only single covalent bonds (1 mark)

- Double covalent: O2, molecules with at least one double covalent bond (1 mark)

MS4. Application of knowledge (3 marks)

- Delocalized electrons can move freely (1 mark)

- Provides a pathway for electrical current (1 mark)

- Layers of atoms allow electrons to move in two dimensions (1 mark)

MS5. Data Analysis/Calculations (3 marks)

- Each H atom shares 1 electron (1 mark)

- 4 H atoms × 1 electron = 4 shared electrons (1 mark)

- + 4 from carbon = 8 shared electrons (1 mark)

MS6. Knowledge Recall (2 marks)

- Unequal sharing of electrons (1 mark)

- Due to differences in electronegativity (1 mark)

- Example: HCl (1 mark)

MS7. Application of knowledge (3 marks)

- High melting and boiling points (1 mark)

- Insoluble in water (1 mark)

- Form network of strong covalent bonds (1 mark)

MS8. Chemical Equation (4 marks)

- (Correct balancing: 2 (1 mark))

- (Correct symbols: 1 mark)

MS9. Data Analysis/Calculations (3 marks)

- Convert percentages to grams: 40g C, 6.7g H (1 mark)

- Convert grams to moles: 40/12 = 3.33 C atoms, 6.7/1 = 6.7 H atoms (1 mark)

- Find the simplest whole number ratio: C3H6 (1 mark)

MS10. Knowledge Recall (2 marks)

- Covalent bonding: Sharing of electrons (1 mark)

- Metallic bonding: Sea of delocalized electrons (1 mark)