:Periodic Table :the original periodic table given to us by mendeleev was organized according to increasing atomic mass :the periodic law states that when elements are arranged in order of increasing atomic number, certain ets of properties recur periodically. :horizontal rows - periods :vertical columns - groups or families :in the mendeleev periodic table, he nwas able to predict properties of undiscovered elements. the table was not cosistent, however, with all the elements properties. :moseley used x-ray emissins and found that similar properties recur periodically when arranged according to increasing atomic number. :moseley developed the periodic law and gave us the modern periodic table. :the electron configuratin of elements can help predict its location in the periodic talbe. the table also separates metals from nonmetals :metals are good conductors of heat and electricity, malleable, ductile, and most have high melting points. (only one is liquid at room temperature (hg)) :nonmetals are conductors. they are brittle in the solid state and many of them are gasses. one is liquid at room temperature (br) :metalloids behave as both metals and nommetals. they are good semiconductors : :Periodic trends :atomic radius is hard to define since there is no precise outer boundary for the electron to be located. the radii then is measured at half the distance between the nuclei of atoms. :the radius is based on the distance between 2 atoms joined by chemical bonds. : 1. covalent radius - half the distance between nuclei of 2 identical atoms joined by a single covalent bond : 2. ionic radius - based on the distance between the nuclei of ions joined by an ionic bond. : 3. metallic radius - half the distance between the nuclei of two atoms (metals) :the more electronic shells in an atom, the larger the atom is so the atomic radii increases from top to bottom in a group. it decreases from left to right through a period. : see geom - chpic1 : :Ionic radius :cations (+) are smaller than the atoms from which they are formed. anions (-) tend to be larger than the atoms from which they are formed. :isoelectronic - atoms with equal number of electrons and with identical conigurations.(examples - na+1 mg+2 and ne) :isoelectronic catins: the more positive the ionic charge, the smaller the ionic radius. :isoelectronic anions: the more negative the ionic charge, the larger the ion. : :isoelectroic anions: the more negative the ionic charge, the larger the ion : :Ionization energy :the quantity of energy a gaseous atom must absorb so that an electron is stripped from the atom. :ionization energy decreases from top to bottom in a family and increases from left to right in a period. :the second ionizatin energy - energy needed to strip a second electron frm a gaseous ion with a charge of +1 : :Electron affinity :measure of the energy change that ocurs when a gaseous atom gains an electron. :if the value for electron affinity is negative, the process is exothermic and gives off energy. if the value is positive the process is endothermic. :electron affinity becomes more negative from left to right across a table and becomes more positive frm top to bottom in a group. :the behavior of atoms and ions in a magnetic field is established by electron configuration. :a diamagnetic atom or ion has no magnetic properties since the paired electros cancel the magnetic field. :a paramagnetic atom or ion has unpaired electrons and the magnetic effect is not cancelled. :the unpaired electrons induce a magnetic field that causes the atom or ion to be attracted to an external magnetic field the more unpaired electrons persent the stronger the attraction. :a substance that is diamagnetic is slightly repelled by a magnetic field, sp it weighs less in a magnetic field. a paramagnetic substance will weigh mor in a magnetic field. : :Electronegativies :describes ab atoms ability to c»ompete for elecctrons with orher atoms to which it is bonded. Electronegativity values range from .7 to 4.0 :electronegativities decrease from to tobottom and increase from left to right :the difference between electronegativities of 2 atoms joined togethercan help predict the type of bond that forms between the two atoms.