Periodicity
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what is periodicity
the regular reputation of properties of elements arising from patterns in their electron arrangement
how are elements arranged in the periodic table
according to their increasing atomic number and the number of protons
what are the 4 blocks
s p d f
why is Zn not a transition metal
because it does not form complete ions with incomplete d sub levels
what is atomic radii
the distance from the nucleus the the outermost electrons
how is atomic radii defined
as half the distance between the nuclei of two bonded atoms of the same element
atomic radii trend
Helium has the smallest atomic radii
why does atomic radii increase down a group
because the electron becomes further away from the nucleus
why does atomic radii decrease across a period
due to the increasing number of protons that pull the electrons in more tightly
what is ionic radius
the radius of an atom ion obtained by adding the distance between two ions and adding the ionic radius of the cation and anion
what is a cation
the positive ion
what is an anion
the negative ion
cations + ionic radius
positive ions radii are smaller than that of their parent atoms
anions + ionic radius
negative ions radii are bigger than that of their parent atoms
way of remembering size order of cation anion and atom
cation
ionic radius trend down a group
cation + anion INCREASE as outer level gets further away from nucleus
ionic radius trend across a period
CATIONS: ionic radii decrease due to the increasing number of protons ANIONS: decrease of atomic radii, but the electrons remain the same for the anions
what is the first ionization energy
the energy required to remove one mole of electrons from one mole of gaseous atoms
ionization energy trend down a group
DECREASES due to the increased distance between the nucleus + outer energy level that reduces the force of attraction between the nucleus and outer electrons
ionization energy trend across a period
INCREASES due to the the increase in effective nuclear charge that causes electrons to be held more tightly
what is electron affinity
the energy change when one mole of electrons is added to one mole of gaseous atoms to form on mole of gaseous ions x + e- = x-
electron affinity ACROSS PERIOD:
increases due to the increase in nucleus charge
electron affinity trend
F has the highest electron affinity
what is electronegativity
its the measure of attraction of a nucleus to bonding electrons