Introduction
The periodic table shows all of the elements arranged in order of increasing atomic number. Mendeleev (among others) first noticed that certain element characteristics or properties tended to repeat in specific intervals. The idea of 'periodic repetition of properties' lead to the table being known as the periodic table of the elements.
Structure 3.1.1 - The periodic table consists of periods, groups and blocks.
- Identify the positions of metals, metalloids and non-metals in the periodic table.
Guidance
- The four blocks associated with the sublevels s, p, d, f should be recognized.
- A copy of the periodic table is available in the data booklet.
Tools and links
Structure 3.1.2 - The period number shows the outer energy level that is occupied by electrons.
- Elements in a group have a common number of valence electrons.
- Deduce the electron configuration of an atom up to Z = 36 from the element’s position in the periodic table and vice versa.
Guidance
- Groups are numbered from 1 to 18.
- The classifications “alkali metals”, “halogens”, “transition elements” and “noble gases” should be known.
Tools and links
- Nature of science, Structure 1.2 - How has the organization of elements in the periodic table facilitated the discovery of new elements?
Structure 3.1.3 - Periodicity refers to trends in properties of elements across a period and down a group.
- Explain the periodicity of atomic radius, ionic radius, ionization energy, electron affinity and electronegativity.
Guidance
Tools and links
Structure 3.1.4 - 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.
- Describe and explain the reactions of group 1 metals with water, and of group 17 elements with halide ions.
Guidance
Tools and links
- Inquiry 2, Tool 2 - Why are simulations often used in exploring the trends in chemical reactivity of group 1 and group 17 elements?
Structure 3.1.5 - 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.
Guidance
- Include acid rain caused by gaseous non-metal oxides, and ocean acidification caused by increasing CO2 levels.
Tools and links
- Structure 2.1, Structure 2.2 - How do differences in bonding explain the differences in the properties of metal and non-metal oxides?
Structure 3.1.6 - 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.
- Deduce the oxidation states of an atom in an ion or a compound.
- Explain why the oxidation state of an element is zero.
Guidance
- Oxidation states are shown with a + or – sign followed by the Arabic symbol for the number, e.g. +2, –1. Examples should include hydrogen in metal hydrides (–1) and oxygen in peroxides (–1).
- The terms “oxidation number” and “oxidation state” are often used interchangeably, and either term is acceptable in assessment.
- Naming conventions for oxyanions use oxidation numbers shown with Roman numerals, but generic names persist and are acceptable. Examples include NO3– nitrate, NO2– nitrite, SO42– sulfate, SO32– sulfite.
Tools and links
- Reactivity 3.2 - How can oxidation states be used to analyse redox reactions?
Structure 3.1.7 - Discontinuities occur in the trend of increasing first ionization energy across a period. (HL)
- Explain how these discontinuities provide evidence for the existence of energy sublevels.
Guidance
- Explanations should be based on the energy of the electron removed, rather than on the “special stability” of filled and half-filled sub-levels.
Tools and links
Structure 3.1.8 - Transition elements have incomplete d-sublevels that give them characteristic properties. (HL)
- Recognize properties, including: variable oxidation state, high melting points, magnetic properties, catalytic properties, formation of coloured compounds and formation of complex ions with ligands
Guidance
- Knowledge of different types of magnetism will not be assessed.
Tools and links
- Nature of science, Structure 2.3 - What are the arguments for and against including scandium as a transition element?
Structure 3.1.9 - The formation of variable oxidation states in transition elements can be explained by the fact that their successive ionization energies are close in value. (HL)
- Deduce the electron configurations of ions of the first-row transition elements.
Guidance
Tools and links
Structure 3.1.10 - 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. (HL)
- Apply the colour wheel to deduce the wavelengths and frequencies of light absorbed and/or observed.
Guidance
- Students are not expected to know the different splitting patterns and their relation to the coordination number.
- The colour wheel and the equation c = λ f are given in the data booklet.
Tools and links
- 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?
In Structure 3.1 - The periodic table: Classification of elements
- 3.1.1 - The structure of the periodic table
- 3.1.2 - Electronic structure
- 3.1.3 - Periodicity
- 3.1.4 - Trends in properties of elements
- 3.1.5 - Metallic and non-metallic properties
- 3.1.6 - The oxidation state
- 3.1.7 - Discontinuities in 1st ionization energy
- 3.1.8 - Transition elements
- 3.1.9 - Variable oxidation states in transition elements
- 3.1.10 - Transition element complexes