Chapter 2 - The Periodic Table Flashcards
what is effective nuclear charge (Zeff)
measure of the net positive charge experienced by the outermost electrons; causes electron cloud to bind more closely and tightly to the nucleus
what is the trend for effective nuclear charge along the periodic table?
increases from left to right within a period, stays more or less constant within a group
how do non-valence electrons affect effective nuclear charge?
cancel some of it out
what is atomic radius?
one-half of the distance between the centers of two atoms of an element that are briefly in contact with each other
what is the trend for atomic radius along the periodic table?
decreases from left to right within a period (zeff increasing), increases down a group (increasing quantum number)
what are the trends for ionic radii along the periodic table?
nonmetals radii increase, those closer to the metalloid line are larger (they gain the most electrons
metals radii decrease, those closer to the metalloid line are smaller (they lose the most electrons)
what is ionization energy?
(ionization potential) energy required to remove an electron from a gaseous species, requires input of heat (endothermic process)
what is the trend of ionization energy along the periodic table?
increases from left to right along a period, decreases down a group (more difficult to remove an electron the closer bound it is to the nucleus)
how does the second or third ionization energy compare with the first?
Subsequent removal of second or third electron ALWAYS requires increasing amounts of energy because they are being removed from increasingly positive species
why are groups 1 and 2 called active metals?
they have such low ionization energies
what is electron affinity?
energy dissipated by a gaseous species when it gains an electron, an exothermic process, the stronger the electron pull between the nucleus and the valence shell electrons, the greater the energy release will be when the atom gains the electron
what is the trend of electron affinity along the periodic table?
increases across a period from left to right, decreases down a group
what are the ionization energies like for noble gases?
extremely high, don’t want to lose an electron
what are the electron affinities like for noble gases?
zero, don’t desire another electron
what is electronegativity?
measure of attractive force that an atom will exert on an electron in a chemical bond
