Mr. Strickland's Chemistry     pi-sigma

Topic 3  Periodicity

 

Topic 3.1  Periodic Table

Essential idea: The arrangement of elements in the periodic table helps to predict their electron configuration.

Understandings:

  • The periodic table is arranged into four blocks associated with the four sub-levels — s, p, d, and f.
  • The periodic table consists of groups (vertical columns) and periods (horizontal rows).
  • The period number (n) is the outer energy level that is occupied by electrons.
  • The number of the principal energy level and the number of the valence electrons in an atom can be deduced from its position on the periodic table.
  • The periodic table shows the positions of metals, non-metals and metalloids.

 

Applications and skills:

  • Deduction of the electron configuration of an atom from the element’s position on the periodic table, and vice versa.

 

Guidance:

  • The terms alkali metals, halogens, noble gases, transition metals, lanthanoids and actinoids should be known.
  • The group numbering scheme from group 1 to group 18, as recommended by IUPAC, should be used.

 

International-mindedness:

  • The development of the periodic table took many years and involved scientists from different countries building upon the foundations of each other’s work and ideas.

 

Theory of knowledge:

  • What role did inductive and deductive reasoning play in the development of the periodic table? What role does inductive and deductive reasoning have in science in general?

 

Utilization:

  • Other scientific subjects also use the periodic table to understand the structure and reactivity of elements as it applies to their own disciplines.

 

Topic 3.2  Periodic Trends

Essential idea: Elements show trends in their physical and chemical properties across periods and down groups.

Understandings:

  • Vertical and horizontal trends in the periodic table exist for atomic radius, ionic radius, ionization energy, electron affinity and electronegativity.
  • Trends in metallic and non-metallic behavior are due to the trends above.
  • Oxides change from basic through amphoteric to acidic across a period. Applications and skills: • Prediction and explanation of the metallic and non-metallic behavior of an element based on its position in the periodic table.
  • Discussion of the similarities and differences in the properties of elements in the same group, with reference to alkali metals (group 1) and halogens (group 17).
  • Construction of equations to explain the pH changes for reactions of Na2O, MgO, P4O10, and the oxides of nitrogen and sulfur with water.

 

Guidance:

  • Only examples of general trends across periods and down groups are required. For ionization energy the discontinuities in the increase across a period should be covered.
  • Group trends should include the treatment of the reactions of alkali metals with water, alkali metals with halogens and halogens with halide ions.

 

International-mindedness:

  • Industrialization has led to the production of many products that cause global problems when released into the environment.

 

Theory of knowledge:

  • The predictive power of Mendeleev’s Periodic Table illustrates the “risk-taking” nature of science. What is the demarcation between scientific and pseudoscientific claims?
  • The Periodic Table is an excellent example of classification in science. How does classification and categorization help and hinder the pursuit of knowledge?