General Chemistry - The Periodic Table

MCAT General Chemistry Chapter 2

Periodic Table of Elements

Ordering known elements by atomic number revealed a pattern of periodically recurring physical and chemical properties.

Periodic Law

Chemical and physical properties of the elements are dependent, in a periodic way, upon their atomic numbers

A Elmenets (Representative Elements)

Groups IA - VIIIA. Elements have their valence electron in orbitals of s or p subhsells

B elements (nonrepresntative)

Include transition elements (valence electrons in s and d subhsells and the lanthanide and actinide series, have valence e in f and s subshells.)

Metal Characteristics

Lustrous solid (except mercury), high melting points and densities, malleabile and ductile, low effective nuclear charge, low EN, large atomic radius, small ionic radius, low IE low electron affinity, good conductors of heat and electricity.

Nonmetal Characteristics

Generally brittle in solid state, show little or no metalic luster, high ionization energy, electron affinities, electronegativites, small atomic radii, large ionic radii

Metalloids

EN and ionization energies of metalloids lie between those of metal and nonmetal, physical properties vary

Effective nuclear charge

A measure of net positive charge experienced by outermost electron

Atomic Radius

Equal to one half of the distance between centers of two atoms of an element that are briefly in contact with eachother

Ionic radius

Tje average dostamce frp, cemter pf mic;eis tp edge pf ots e;ectrpm c;pid

Ionization Energy

The energy required to remove an electron from gaseous species

First Ionization energy

Energy necessar to remove the first electron

Second ionization energy

Energy necessary to remove second electron from univalent cation to form divalent cation

Electron affinity

Energy disipated by a gaseous species when it gains an electron

Electron negativity

Measure of attractive force their an atom will exert on an electron in a chemical bond, related to ionization energy

Alkali Metals Properties

Group 1, classical physical properties beside lower density, largest atomic radii in respective perioids, low Zeff value, low ionization energy, low electron affinity, low electronnegativty

Alkaline Earth Metals

Posses properties of metals, Have higher effective nuclear charge and thus smaller atomic radii, reactive not found in neutral state

Halogens

Highly reactive nonmetals, physical properties variable, standard range from gaseous to liquid to solid, found as ions or diatomic molecules

Noble Gases

Filled valence shell, minimal reactivity, high ionization energy, no measurable electronegativity, extreme low boiling point

Transition Metal (B)

Low electron affinities, low ionization energy, low EN, very hard, high melting and boiling points, malleable and good conductor due to loosely held electron that filled orbital in shell, different possible oxidation states