Periodic Trends Flashcards
(21 cards)
What is principal quantum number (n)?
main energy level, determines part of e- energy
n=1,2,3,…
WHat is angular momentum quantum number (l)?
shape (type) of orbital
l= 0 to n-1
What is the magnetic quantum number (m (sub)l)
orbital orientation in space
= -l to +l
What is spin quantum number (m (sub)s)
orientation of e-s magnetic moment in magnetic field
=+/- 1/2
What is the effective nuclear charge? + equation
attraction between protons in nucleus and electrons
atomic number - screening constant
core electrons screen outer electrons
What are contributiosn of electrons for screening constant
zero for groups to right
0.35 from electrons in same group (except 1s where 0.3)
n-1 = 0.85
n-2+ =1
if nd or nf group 1 for each electron left of group considered
Describe periodic trends of Zeff
increases across a period = decrease in atomic size
decreases down a column = increase in atomic size
What does a larger Zeff make atomic size smaller?
because electrons held closer to nucleus
What is ionization energy?
the amount of energy required to remove electron from an isolated neutral atom in the gaseous state
hwat are periodic trends for ionization energy?
increases across
decreases down
why does ionzation energy decrease down and increase across
down a column valence electrons further from nucleus
across a row increased effective nuclear charge
What are the 2 exceptions to first iomnizatrion energy
2A higher than 3A
6A lower than 5A
What is electron affinity?
energy change when an atom in the gaseous state gains an electron
What are perioidc trends of electron affinity?
increases across decreases down
Why does electron affinity increase across and decrease down
down decreases as electron farther from nucleus
across increases as effective nuclear charge increases
What is electronegativity?
ability of a molecule to draw electrons to itself
What is periodic trends of electronegativity?
increases across decreases down
What is the uniqueness principle?
the chemistruy of second periodic elements (Li, Be, B, C, N, O, F, Ne) can be significantly different to other elements in the same group
WHy do second perioidc elements fit uniqueness principle?
exceptionally small size
enhanced abilkity to form pi bonds
unavailability of d orbitals
What is the diagonal effect?
similarities diagonally across periodic tabe in ionic size, electronegativity, charge density
What is inert pair effect?
7 elements just off of staircase often form compounds where oxidation state is two less than expected group valence
