atomic radius
half the distance between the nuclei of two adjacent atoms of the same element
atomic radius: down a group
radius increases - more energy levels create a larger radius
atomic radius: across a period
radius decreases - there are more protons and no new energy levels (Zeffective is greater) so the radius shrinks
shielding effect
decrease in the attraction of the valence electrons towards the protons due to the presence of the energy levels between the nucleus and valence electrons
effective nuclear charge
the perceived attraction the electron has for the protons in the nucleus; the more shells there are, the weaker the Zeffective becomes b/c the protons are attracted to the electrons closest to the nucleus
Ionization energy
amount of energy required to remove one valence electron form an atom and form a +1 ion
ionization energy: down a group
energy decreases - Zeff is weaker due to more shielding, so the electrons require less energy to remove
ionization enery: across a period
energy increases - same energy level but more protons so Zeff is greater and the electron is harder to remove
ionization energy: exceptions
Group 13, Group 16
group 13 exception
removing the last valence electron is easier then it should be because the full "s" sub level acts as a mini shield
group 16 exception
due to electron repulsion, the 4th "p" electron is easier to remove
second ionization energy
the amount of energy needed to remove the second (third,fourth,etc) valence electron from an atom increases
electronegativity
the attraction an element has for the electrons in a chemical bond
chemical bond
two electrons that are linking two atoms together
electronegativity: down a group
electronegativity decreases - the more energy levels, the greater the shielding effect = the lower attraction for electrons
electronegativity: across a period
electronegativity increases - there are more protons, so the shields stay the same and the Zeff is greater causing more electrons to be attracted to the nucleus
electron affinity
the energy that is lost when an atom gains an electron - forms an anion; any time an attraction/bond is formed, energy is released;any time an attraction/bond is broken energy is gained
electron affinity: down a group
electron affinity decreases - the increase in electron shields decreases the atoms ability to attract electrons
electron affinity: across a period
electron affinity increases - it gains protons but the number of energy levels remains the same (the Zeff increases), so there is a greater attraction for electrons
electron affinity: exceptions
group 2,15,18
group 2 exception
s" sublevel is full, so when it gains an electron, you need to add to the "p" sub level which is further away from the nucleus
group 15 exception
all "p" sublevels are half way full, so another electron will experience electron repulsion, decreasing the attraction
group 18 exception
the valence shell is full so there's no room for another electron