periodic trends
DESCRIPTION
Periodic Trends. Chemical Periodicity. Atoms participate in chemical reactions in order to fill their outermost s and p sublevels. Some definitions…. ionization energy – energy required to remove an electron from an atom electron affinity – energy required to add an electron to an atom - PowerPoint PPT PresentationTRANSCRIPT
Chemical Periodicity
Atoms participate in chemical reactions in order to fill their outermost s and p sublevels.
Some definitions… ionization energy – energy required to
remove an electron from an atom
electron affinity – energy required to add an electron to an atom
electronegativity – tendency of atoms to attract e- when they are bonded to another atom
Four Classes of Elements
Noble Gases outermost s, p filled do not react
Representative Elements outermost s or p only partially filled
Transition Metals outermost s filled adding e- to d sublevel
Inner Transition Metals outermost s sublevel is filled adding e- to f sublevel
Trends in Atomic SizeWithin Groups: size increases as you move down e- are being added to additional energy
levels
Within Periods: size decreases left to right because of
increase in effective nuclear charge larger # of p+ causes atom to “shrink” inner e- shield nucleus
Trends in Ion Sizescation positive ion atom LOSES electron(s) smaller than atoms from which they are
madeanion negative ion atom GAINS electron(s) larger than atoms from which they are
made
Trends in Ionization EnergyWithin Groups: IE decreases as you move down
• e- are farther from nucleus• e- not held as tightly in larger atoms
Within Periods: IE increases from left to right nucleus has greater attraction for e- in
smaller atoms
Trends in Electronegativity
Within Groups: decreases as you move down atoms too large for nucleus to attract e-
Within Periods: increases left to right atoms get smaller, easier to attract e-