From Citizendium, the Citizens' Compendium
- Chemistry : The science of matter, or of the electrical or electrostatical interactions of matter.
- Elements : In one sense, refers to species or types of atoms, each species/type distinguished by the number of protons in the nuclei of the atoms belonging to the species/type, each species/type having a unique number of nuclear protons; in another sense, refers to substances, or pieces of matter, each composed of multiple atoms solely of a single species/type.
- Periodic Table of Elements : A tabular method of displaying the chemical elements.
- Fluorine : A chemical element, having the chemical symbol F, and atomic number (the number of protons) 9.
- Chlorine : A chemical element, having the chemical symbol Cl, and atomic number (the number of protons) 17.
- Bromine : A chemical element, having the chemical symbol Br, and atomic number (the number of protons) 35.
- Iodine : A halogen and chemical element that has the symbol I and atomic number 53.
- Astatine : A chemical element having the chemical symbol At and an atomic number (the number of protons) of 85.
- Electronegativity : Electronegativity is a measure of the tendency to attract electrons. Generally, it is used in the context of describing one species of atom's (element's) attraction of electrons in a chemical bond relative to another species. A higher electronegativity number indicating a greater tendency for attraction.