The representative elements are the A elements found in groups IA – VIIIA.
Representative elements have their valence electrons in orbitals of either s or p shells. The roman numeral and the letter designation determine the electron configuration. As an example, an element in Group VA has five valence electrons with the configuration s2p3.
Non-representative elements include the transition elements, which have valence electrons in the s and d shells, and the lanthanide and actinide series, which have valence electrons in the s and f shells. They have unexpected electron configurations. As an example, chromium and copper are 4s13d5 and 4s13d10 respectively.
Practice Questions
Khan Academy
Qualitative analysis of contaminated water supply
MCAT Official Prep (AAMC)
Key Points
• Representative elements include the s and p block
• Non-representative elements exist in the d and block
• They often have unexpected electron configurations
Key Terms
electron configuration: the distribution of electrons of an atom or molecule in atomic or molecular orbitals
roman numeral: any of the symbols used in a system of numerical notation based on the ancient Roman system
valence electron: an outer shell electron that can participate in chemical bonds
transition elements: any of the set of metallic elements occupying a central block (Groups IVB–VIII, IB, and IIB, or 4–12) in the periodic table
actinide: a series of elements with atomic numbers from 89 to 103, actinium through lawrencium
lanthanide: consists of the 14 elements, with atomic numbers 58 through 71, that follow lanthanum on the periodic table of elements.
