Chapter 2 Flashcards
what is a molecule
consist of multiple molecules (like or unlike) bonded together
1 mole (Avogadro’s number)
6.022 x 10^23
octet rule
each atom will act in such a way to obtain 8 electrons in its valence shell
2 main intramolecular forces
ionic and covalent bonds
ionic bonds
strong chemical bonds that hold together ions electrons are completely transferred from the cation to the anion metals tend to form ionic bonds with non metals
covalent bonds
involves the sharing of an electron pair between 2 atoms
non polar covalent bonds
form between atoms that have very similar or identical electronegativity values
polar covalent bonds
form between atoms where the more electronegative atom will attract the shared electrons more strongly making it partially negative while the other atom will be partially positive (dipole moment)
coordinate covalent bond
(dative bond) forms when the shared electrons are derived from a lone pair on only one of the bonded atoms
bond order
describes the number of bonds between 2 atoms
single bond
sigma bond
double bond
1 sigma and 1 pi bond
triple bond
1 sigma and 2 pi bonds
bond length
single is longest, triple is shortest
bond energy
takes more energy to break triple bond than double than single
metallic bonding
when metal atoms are joined together and electrons become delocalized “sea of electrons” = conduct heat and electricity
intermolecular forces
attractive forces between molecules that are notably weaker than intramolecular bonds
intramolecular vs intermolecular forces
Intramolecular forces are the forces that hold atoms together within a molecule. Intermolecular forces are forces that exist between molecules.
London-dispersion forces (VDW)
weakest intermolecular force The London dispersion force is a temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles. This force is sometimes called an induced dipole-induced dipole attraction.
dipole-dipole interactions
Dipole -dipole interactions occur when the partial charges formed within one molecule are attracted to an opposite partial charge in a nearby molecule. Polar molecules align so that the positive end of one molecule interacts with the negative end of another molecule. (stable dipoles already exist)
hydrogen bonds
hydrogen bonding occurs when a hydrogen atom attached to a nitrogen, oxygen, or fluorine atom is attracted to the lone pair of a nitrogen, oxygen or fluorine atom on another molecule
ion-dipole forces
occur between ions and molecules with a dipole
ionic interactions
occur between 2 molecules with a full charge
2 regions of electron density
sp
3 regions of electron density
sp2
4 regions of electron density
sp3
Linear
electron rich regions: 2
bonded atoms: 2
lone pairs: 0
bond angle: 180 degrees
trigonal planar
electron rich regions: 3
bonded atoms: 3
lone pairs: 0
bond angle: 120 degrees
tetrahedral
electron rich regions: 4
bonded atoms: 4
lone pairs: 0
bond angle: 109.5 degrees
trigonal pyramidal
electron rich regions: 4
bonded atoms: 3
lone pairs: 1
bond angle: 107 degrees
bent
electron rich regions: 4
bonded atoms: 2
lone pairs: 2
bond angle: 104.5 dergees
trigonal bipyramidal
electron rich regions: 5
bonded atoms: 5
lone pairs: 0
bond angle: 90, 120, 180
octahedral
electron rich regions: 6
bonded atoms: 6
lone pairs: 0
bond angle: 90, 180 degrees
