Chapter 4 Lecture Flashcards
molecular formulas
shows atoms within molecule + proportions of the atom
structural formulas
line-bond structures that give more information vs. the molecular formula (connections of the atoms)
how do you draw structural formulas?
- know how many covalent bonds an atom can form
- count total # of valence electrons
- use covalent bonds to connect atoms to each other
- add onto central atoms - add pairs of electrons to complete octets
- add other lone pairs
condensed strucutral formulas
abbreviated formulas
skeletal structures
no letters shown; covalent bonds are presented by lines
covalent bonds
atoms that share a pair of valence electrons
electronegativity
defined as the ability of atom to attract bonding electrons - sometimes electrons are not always shared equally
nonpolar covalent bonds
the difference in electronegativity is less than 0.5 - not significant enough (equal sharing of bonding electrons)
polar covalent bonds
the difference in electronegativity is between 0.5-0.9 - significant enough (unequal sharing of bonding electrons)
ionic bonds
the difference in electronegativity is more than 0.9 (creation of an ionic bond)
drawing polar covalent bonds
- head of arrow always points to more electronegative atom
- determines polarity of molecule
- polar molecules dissolve in water
polarity
one end of the molecule is positive, and another end is negative
rules for polarity
- if a molecule contains only one non-polar bond, it is always NONPOLAR
- for a molecule to be polar, it must have AT LEAST ONE POLAR BOND
- not ALL molecules containing polar covalent bonds are polar
what are some of the molecular 3d shapes?
- tetrahedral
- bent
- linear
- pyramidal
*have to know # of bonds and lone pairs of electrons
*electrons are as far apart as possible
what are the non-covalent interactions?
these are attractive interactions that do not involve the sharing of valence electrons
-relatively weak, but become strong once in large quantities
permanent partial charges
- hydrogen bonds
- dipole-dipole interactions
temporary partial charges
- london forces - hydrophobic forces
dipole-dipole bond
attraction of neighboring polar groups to one another
hydrogen bonds
interaction of an electronegative atoms (like N or O) with an H atom that is covalently attached to another electronegative atom (N or O)
london forces
nonpolar molecules (or basic nonpolar portions of a molecule) that are “attracted” to one another
- just means our hydrophobic molecules are avoiding water as much as possible - just looks like “attraction”
- greater contact of non-polar areas, the stronger the force !
organic chemistry
the study of C-based compounds
functional groups
an atom or groups of atoms or bonds that give the molecule a particular set of chemical properties
