Periodicity Flashcards
Moseley PT
Current. Increasing atomic number going across in periods and similar properties going down in groups
Mendeleev PT
Past. By atomic mass in groups and properties in periods
Mendeleev gaps in PT
There were gaps in places where no known element could fit. Scientists had to predict it.
The periodic Law
groups go up and down with simialr properties and periods go across with atomic number
atomic radii def
half the distance between 2 nuclei of the same element
ionic radii def
size of the changed atom after becoming an ion
electronegativity def
the tendency to attract e- from another element’s atom when chemically combining
ionization energy def
measures the energy required to move an e- from outermost level
electronaffinity def
energy lost when an atom gains e-
atomic radii trend
increases going down & decreases across
ionic radii trend
neutral atoms increase going across & decrease going down
electronegativity trend
increase across and decrease down groups
ionization energy trend
increases across and decreases going down
reactivity trend
increases across and decreases down
valance e- trend
increase across table and remains the same down
nuclear effect
The attractive positive charge of nuclear protons acting on valence electrons.
shielding electrons
the blocking of valence shell electron attraction by the nucleus, due to the presence of inner-shell electrons.
valance e- distance from nucleus
can increase and decrease radii because the farther the vale- the more shielding electrons but make the radii larger from added protons. When vale- are closer to nucleus the vale- are easier to lose making a smaller radii
number of occupied energy levels
additional occupied energy levels, increase going down and get more e- added to same energy level going across.
charge density
The periodic trend is that charge density decreases as one moves down the periodic table because the charge remains constant, but the size increases. As the charge increases and the size decreases, the charge density increases across
Atoms are
neutral
cations
lose e-, positive, metals, smaller than neutral atom
Anions
gain e- , negative, nonmetal, bigger then neutral atom
Ions
charged are stable like noble gasses w/ 8 vale-
noble gasses
are stable=inert= dont react during normal conditions, w/ vale-
octet rule
every atom wants to be a stable like a noble gas with 8 vale-
