Chem 105 Test 2 (Ch. 3-5) Flashcards
main-group elements
groups 1-2 (s orbitals)
groups 13-18 (p orbitals)
transition elements
groups 3-12 (d orbitals)
inner transition elements
f orbitas
the Pauli Exclusion principle
no two electrons in an atom may have the same set of four quantum numbers
the sublevels (s, p, d, f, etc.) in each principal energy shell of hydrogen, or other single electron systems, all have (the same/different) energy, so they are said to be ?
the same; degenerate
for multi-electron atoms, the energies of the sublevels are split due to
charge interaction, shielding, and penetration
aufbau principle
electrons fill atomic orbitals from lowest energy to highest
Coulomb’s Law
for like charges, the PE is positive and decreases as the particles get farther apart (r increases)
for opposite charges, the PE is negative and becomes more negative as the particles get closer together
the strength of the interaction increases as the size of the charges increases
essentially, E is proportional to q1q2 / r
shielding
when repulsion from other electrons in the nucleus cause an electron to experience a net reduction in attraction to the nucleus
effective nuclear charge (Zeff)
the total amount of attraction that an electron feels for the nucleus’s protons
attraction between nucleus protons and orbiting electrons is related to
the orbital type the electron occupies (ex: e-s in the s orbital are better shielders than e-s in p orbitals - s>p>d>f)
the degree of penetration is related to
the orbital’s radial distribution function
penetration causes the energies of sublevels in the same principal level to
not be degenerate
Hund’s rule
when filling orbitals that have the same energy (degenerate), place one electron in each orbital before completing pairs
electrons in lower-energy shells
core (inner) electrons
electrons in all the sublevels with the highest principal energy level are called the
valence electrons
one of the most important factors in the way an atom behaves, both chemically and physically, is ? because
the number of valence e-s because the valence e-s participate in bonding & the valence shell is where e-s are lost or added to make cations/anions
some transition metals have irregular electron configurations in which the ns only partially fills before the (n-1)d or completely filled sublevel - which do we need to know?
Cr, Mo (half-filled sublevel)
Cu, Ag (completely filled sublevel)
Zeff periodic trend
increases as you go across a period and decreases as you go down a column
Zeff is calculated by
Z - S
Z = nuclear charge, S = number of electrons in lower energy levels
atomic radii periodic trend
decreases across a period and increases down a group
atomic radii for transition elements
increases down the column but roughly the same across the d block
cation radius is (smaller/larger) than atom radius and anion radius is (smaller/larger) than atom radius
smaller, larger
ionization energy periodic trend
decreases down a group and increases across the period
ionization energy
the minimum energy needed to remove an electron from an atom or ion in the gas phase
second ionization energy will be (smaller/larger) than first
larger (think Zeff)
electron affinity
the energy associated with the addition of an electron to the valence shell of an atom that is in the gas phase
electron affinity periodic trend
becomes more negative across a period (increases) and no definite trend for down a group
metal characteristics
malleable, ductile, shiny, conduct heat/electricity, form cations, oxidized
nonmetal characteristics
brittle, dull, electrical/thermal insulators, form anions, reduced
metallic character
how closely an element’s properties match the ideal properties of a metal
metallic character periodic trend
decreases across a period and increases down a group
ionic bonding
metal & nonmetal
covalent bonding
nonmetal (becomes the cation) & nonmetal (becomes the anion)
ionic bonds involve the
transfer of electrons from one atom to another
covalent bonds involve the
sharing of electrons between two atoms
molecular compounds are composed of
atoms covalently bonded to each other
ionic compounds are composed of
ionic bonds
chemical formula
represents a compound; indicates the type and number of each electron present in the compound
chemical formulas can generally be categorized into three different types
empirical, molecular, structural
empirical formula
gives the relative number of atoms of each element in a compound; the simplest whole number ratio representation of the group and number of elements present in a molecule
molecular formula
gives the actual number of atoms of each element in a molecule of a compound