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Chemistry 1.5 Describe atomic structure and bonding

Achievement criteria

The level of achievement that you will reach is decided by the way you answer each question. The key words are describe, explain, and discuss aspects of atomic structure and bonding.

Achievement

• Describe atomic structure and bonding.
• This means you can:
  
  • relate the number of protons, neutrons, and electrons in an atom (including isotopes) or a monatomic ion, to the atomic number, mass number, and charge
  • state the electron arrangement of atoms or ions of the first 20 elements in the periodic table
  • relate the charge on monatomic ions to the position of the element in the periodic table
  • draw Lewis diagrams of atoms (selected from the first 20 elements in the periodic table) and molecules with single bonds only (for example H₂O, CH₄, H₂, Cl₂, and PCl₃) (molecules with more than four pairs of electrons around the central atom are excluded)
  • distinguish between ionic and covalent bonds and predicting the type of bonding in given examples of ionic and covalent compounds (compounds are limited to those containing two elements only).

Achievement with Merit

• Link principles of atomic structure, bonding, and selected properties such as conductivity, melting point, and boiling point of ionic and molecular compounds.
• This means you can:
  
  • distinguish between states of ionic and molecular substances, in terms of particle separation, energy, particle motion, and attractive forces
  • draw Lewis diagrams of molecules with multiple bonds (for example O₂, N2 and CO₂) (molecules with more than four pairs of electrons around the central atom are excluded)
  • use atomic structure to justify the type of bonding in ionic and covalent compounds
  • relate the similarities in the chemical properties of elements in the same group to the number of valence electrons or the elements’ positions on the periodic table (elements will be selected from groups 1, 2, 16, 17, and 18)
  • relate the type of bonding to a selected property.

Achievement with Excellence

• Discuss selected properties, such as conductivity, melting point, and boiling point of ionic and molecular compounds, in terms of atomic structure and bonding.
• Discussions of the properties of the substances must be related to their constituent particles (molecules or ions) and the strength of attractive forces between them.

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