Ch 1 Chemical Bonding and Structure Flashcards
Valence shell
-outermost shell of electrons surrounding an atom
-atoms gain/lose valence e- to get noble gas configuration
-octet rule: eight valence electrons
Covalent chemical bond
sharing 1+ electron pairs between 2 atoms
-POLAR-
-electronegativity (polarization direction)
Electron configuration
way electrons are distributed through atomic orbitals
-Aufbau Principle: buildup little by little
-Hund’s Rule: electrons are put into own orbitals before being paired
Orbitals
define where an electron is most likely to be found
-node: where an electron cannot be found
Molecular Orbitals
combined atomic orbitals make molecular orbitals (addition: bonding molecular orbitals; subtraction: antibonding molecular orbitals)
# of AOs = # of MOs
Bond order = 1/2 (electrons in bonding MOs - electrons in antibonding MOs)
Lewis structures
Valence electrons number
bonds + nonbinding electrons = group number = number of valence electrons
Ionic compounds
components are ion
-can dissociate into free ions
-electrostatic attraction between ions (same in all directions – no dipole)
Formal charge
= group number (number of valence electrons) - number of bonds - nonbinding electrons
-just bookkeeping
Resonance Structures
2+ extreme forms in which a molecule may exist
-lowers electron energy: have more space to move around than being confined to one bond
-structures are not in Equilibrium (molecule is weighed average of the two structures)
Atomic connectivity
how atoms in a molecule are connected
Molecular geometry
how far apart atoms are, and how they’re arranged in space
-influences chemical reactivity
-bond length: distance between 2 bonded nuclei ((increases as period number increases, decreases along row and bond order))
*bond order = number of bonding electrons - antibonding /2
-bond angle: angle between two bond to a single atom (determine molecular shape); want to be far as possible
Molecular shapes
Linear
Bent
Trigonal Planar
Trigonal Pyramidal
Tetrahedral
Dihedral Angle
angle of an atom relative to an atom it’s bonded to
Determining hybridization
sp - atoms + lone pairs = 2 (one s and one p orbital)
sp2 - atoms + lone pairs = 3 (one s and two p orbitals)
sp3 - atoms + lone pairs = 4 (one s and three p orbitals)
*lone pairs sit in orbitals and take up more space than actual atoms
Dipole Moment
-covalent bonds only
Measure of uneven electron distribution in a compound
-sometimes cancel each other out
Permanent Dipole? Polar molecule
