Atoms are the basic building units of matter around us. Atom is consists of three basic particles: positively charged protons, negatively charged electrons and neutral neurons. Each atom is a different combination of these particles. The combination of these particles decides the properties of matter. Electrons revolve around the nucleus. The nucleus is at the center of the atom and consists of protons and neutrons. The pathway of electrons around the nucleus is called orbit. An atom is neutral due to equal number of electrons in the orbits and number of protons in the nucleus.
An atom or molecule in which the total number of electrons is not equal to the total number of protons is called an Ion. It carries either negative or positive charge. An anion is an ion with more electron than protons, giving it a net negative charge. A cation is an ion with fewer electrons than protons, giving it positive charge. An ion consisting of a single atom is called an atomic or monatomic ion; if it consists of two or more atoms, it is a molecular or polyatomic ion.
Formation of ions: Ionization
Monatomic ions are formed by gain of electrons to the outermost shell or lose of electrons from this shell. The process of gaining or losing electrons from a neutral atom or molecule is called ionization.
Sodium atom (Na) whose atomic number is 11 has one electron in its valence shell, surrounding inner shells with 2 and 8 electrons. A sodium atom loses its extra becoming a cation :
Na –> Na+ + e–
Chlorine (Cl) whose atomic number is 17 has 7 electrons in its valence shell. Thus a chlorine atom gains an elector to attain a stable configuration with 8 electrons in valence shell. Chlorine forms an anion in this process.
Cl + e– –> Cl–
Polyatomic and molecular ions are often formed by the gaining or losing of elemental ions such as H+ in neutral molecules. For example, when ammonia, NH3, accepts a proton, H+, it forms the ammonium ion, NH+4.
The energy required to detach an electron in its lowest energy state from an atom or molecule of a gas with less net electric charge is called the ionization potential, or ionization energy. Ionic bonding is a kind of chemical bonding that arises from the mutual attraction of oppositely charged ions.
SchoolTutoring Academy is the premier educational services company for K-12 and college students. We offer tutoring programs for students in K-12, AP classes, and college. To learn more about how we help parents and students in Victoria visit: Tutoring in Victoria.