The periodic table consists of periods, groups and blocks.

The period number shows the outer energy level that is occupied by electrons.

Elements in a group have a common number of valence electrons.

Periodicity refers to trends in properties of elements across a period and down a group.

Trends in properties of elements down a group include the increasing metallic character of group 1 elements and decreasing non-metallic character of group 17 elements.

Metallic and non-metallic properties show a continuum. This includes the trend from basic metal oxides through amphoteric to acidic non-metal oxides.

The oxidation state is a number assigned to an atom to show the number of electrons transferred in forming a bond. It is the charge that atom would have if the compound were composed of ions.

Discontinuities occur in the trend of increasing first ionization energy across a period. (AHL)

Transition elements have incomplete d-sublevels that give them characteristic properties. (AHL)

The formation of variable oxidation states in transition elements can be explained by the fact that their successive ionization energies are close in value. (AHL)

Transition element complexes are coloured due to the absorption of light when an electron is promoted between the orbitals in the split d-sublevels. The colour absorbed is complementary to the colour observed. (AHL)

Nature of science, Structure 1.2—How has the organization of elements in the periodic table facilitated the discovery of new elements?

Inquiry 2, Tool 2—Why are simulations often used in exploring the trends in chemical reactivity of group 1 and group 17 elements?

Reactivity 3.2—How can oxidation states be used to analyse redox reactions?

Nature of science, Structure 2.3—What are the arguments for and against including scandium as a transition element? (AHL)

Reactivity 3.4—What is the nature of the reaction between transition element ions and ligands in forming complex ions?

Tool 1, Inquiry 2—How can colorimetry or spectrophotometry be used to calculate the concentration of a solution of coloured ions?

• S3.1.5—Metallic and non-metallic properties show a continuum. This includes the trend from basic metal oxides through amphoteric to acidic non-metal oxides.

  • Deduce equations for the reactions with water of the oxides of group 1 and group 2 metals, carbon and sulfur.

  • Include acid rain caused by gaseous non-metal oxides, and ocean acidification caused by increasing CO2 levels.

Nature of science, Structure 1.2—How has the organization of elements in the periodic table facilitated the discovery of new elements?

Inquiry 2, Tool 2—Why are simulations often used in exploring the trends in chemical reactivity of group 1 and group 17 elements?

Reactivity 3.2—How can oxidation states be used to analyse redox reactions?

Nature of science, Structure 2.3—What are the arguments for and against including scandium as a transition element? (AHL)

Reactivity 3.4—What is the nature of the reaction between transition element ions and ligands in forming complex ions?

Tool 1, Inquiry 2—How can colorimetry or spectrophotometry be used to calculate the concentration of a solution of coloured ions?