25.8 Periodic Trends Flashcards
shielding effect
each filled electron shell between nucleus and valence electrons protects the valence electrons from the attractive force from + protons in nucleus
- more shielding as you go down periodic table
how does Zeff increase?
↗
increase going up (less between shells)
increase going right (add more protons = more attractive force)
atomic radius
size of an atom
atomic radius trend
↙
increase going down (adding more electron shell)
increase going left (less protons in nucleus, less attraction with valence e and less pulling)
ionization energy
amount of energy required to remove least tightly bound electron from an atom (make an anion from it)
ionization energy trend
↗
increase going up (less shielding effect with less shells, so harder to rip off electron)
increase going right (more protons in nucleus, more attraction to valence e so harder to rip off electron)
electron affinity
energy release (- EA, want the extra electron) or required (+ EA, don’t want extra electron) when adding an electron to an atom
KIND of like an opposite to ionization energy (forming an anion instead of cation)
halogen EA value
large, - EA (good)
alkali earth metal EA value
+ EA (bad)
noble gas EA value
+ EA (bad)
EA trend
↗
more negative up and to the right except for noble gases (more negative = release more energy when adding the electron wants the extra electron more)
electronegativity
atom’s ability to pull electrons to itself to form covalent bonds
electronegativity trend
↗
increase going up and to the right
electronegativity comparison (H, C, N, O, F, S, Cl, Br, I)
F > O > N ≈ Cl > Br > I > S > C ≈ H
acidity
how well a compound:
1) donates protons (loses an H)
2) accepts electrons
3) lowers pH
(more acidic = more stable conjugate base)
