Ions and Ionic Compounds

How much an element reacts depends on… Electron Configuration Oxygen vs. Neon Electron Configuration: 1s22s22p4 Orbital Diagram for Neon Electron Configuration: 1s22s22p6 Oxygen: 2p orbital only has 4 electrons can hold 6 electrons Neon: Has a full 2p electron orbital or shell with 6 electrons

Octet Rule A concept of chemical bonding theory that atoms tend to have either an empty valence shell or full valence shell of 8 electrons. All atoms try to get an octet, 8 electrons in their outermost shell by either losing or gaining electrons. This is an attempt to have the electron configuration of a noble gas. *Valence shell: the electrons found in the outermost shell of an atom. Orbital Electrons s 2 p 6 d 10 f 14

Alkali Metals and Halogens Most reactive elements Outer s and p orbital that do not match the Noble gases will react to lose or gain an electron…so the outer orbital will be full.

Cations and Anions Cation: atoms lose electrons Usually metals Anion: atom gains electrons Usually non-metals Ions form in order to achieve an octet (or as close as possible). Ions have different properties than their parent atoms.

Oxidation states, valences

Ion examples

Order of Stability Octet Filled or half filled outer orbital Fill the best they can

Ionic Bonding and Salts Ionic bond: transfer of electrons (opposite charges attract, cations and anions) compound becomes electroneutral (+ = - no net charge)

Sodium Chloride Ionic bond form between sodium cations and chloride anions Electrostatic attraction crystals

Ionic compounds Do not consist of molecules Bonds are strong, multiple attractions High melting point and boiling point Hard and Brittle Conduct electricity (if ions are mobile, in other words melted or dissolved in water)

Conducting electricity

Crystals Crystal lattice: regular pattern in which a crystal is arranged Unit cell: the smallest portion of a crystal lattice that shows a 3-d pattern of the entire lattice

Some examples of unit cells