Chem Ch 4 and 7

Valence electrons

the electrons available to be lost, gained or shared in the formation of chemical compounds (GROUP # SIGNIFIES # OF VALENCE ELECTRONS)

Octet rule

chemical compounds tend to for so that each atom, by gaining, losing or sharing electrons, has an octet (8) electrons in its highest energy level

Many main group elements form ions with a complete octet

Ions formed from a single atom are called monatomic ions

Cation

atoms that lose electrons (identified by their element name)--> Groups 1,2, and 3, named first in compounds

Anion

atoms that gain electrons (named by dropping the ending and adding ide)--> groups 5,6, and 7, second in compounds

Electron cloud

where the electrons are located, outside the nucleus of the atom

Sublevel

s,p,d, and f; 3d regions where electrons are likely to be

Orbitals

space in a sublevel that holds electrons (each orbital holds up to 2 electrons)

Hund’s rule:

every orbital in a sublevel should be singly occupied before an orbital is doubly occupied

Pauli Exclusion Principle:

an orbital must have electrons with opposite spins (one up arrow and one down arrow)

Aufbau Principle:

lower energy levels/orbitals first

energy levels

distance from nucleus

higher the energy level

further from nucleus (energy level formula: 2n squared)

noble gasses

Relatively unreactive and have a complete outer shell