guided notes Flashcards
Atoms form bonds to:
-decrease potential energy
-increase stability
Potential energy is decreased as ->
Bond is formed
How is a bond formed?
two opp forces of attraction balance at the precise distance where potential energy is at a minimum
Forming a chemical bond =
exothermic process (releases energy and stability inc)
Breaking a chemical bond=
endothermic process (absorbs energy and Potential energy Inc and stability dec)
Compounds have less potential energy than the ->
individual atoms they are formed from (more stable)
Atoms gain a stable full valence energy level by ->
bonding with other atoms
Octet rule:
bonds form btwn atoms by gaining, losing, or sharing e- in order to have an octet of e-
When chemical bonds form, valence e- are: (3)
-transferred from one atom to another (ionic)
-shared btwn atoms (covalent)
-free moving in sea of e- (metallic)
The electronegativity difference btwn tow bonded atoms determines _>
type of bond
0.0-0.3 =
non polar covalent
0.3-1.7=
polar covalent
1.7-3.3 =
ionic
Two major categories of compounds based on bonding:
Ionic compounds and molecular (covalent ) compounds
Ionic compound:
metal bonded with nonmetal or compound containing a polyatomic ion
molecular (covalent) compound:
tow or more nonmetals combined
Ionic Compound properties:
-high melting point
-high boiling point
-dissolve in water
-conducts electricity in solution and as liquids
Covalent (molecular) compound properties:
-lower melting points
-lower boiling points
-do not conduct electricity
(ionic bond) metal loses e- to form a
cation (+ ion)
(ionic bond) nonmetal gains e- to form a :
anion (- ion)
What forms an ionic bond?
an electrostatic attraction
covalent bonds:
forec between tow atoms due to a sharing of one or more e-, forming a molecule
Metallic bonds:
occurs btwn atoms of metals
(metallic bond) Where are the valence e- held?
loosely held in a moble sea of valence e-
(metallic Bonding) what does this type of bonding account for?
some unique properties of the unique properties of metals (conduct electricity. luster, and malleability)
Lewis Dot Notation:
dots around the element symbol represent the # of valence e-
(Lewis structure ions) cation gets a_____ to show loses of e-
bracket
(lewis structure ions) Anion gets _______to show gain of e-
full bracket
(lewis structure polyatomic ion) polyatomic ions are represented as a ->
complete unit
-brackets go around whole structre with charge outside
(lewis structures molecular compounds) dashes btwn atoms represent:
covalent bonds
VSEPR
valence shell electron pair repulsion theory
VSEPR theory predict the:
goemetric shape of the molecule
VSEPR Theory:
the repulsion forces of valence-level e- will cause atoms of a molecule to spread out as far apart as possible
molecular geometry:
the 3 dimensional arrangement of a molecule’s atoms
Lone pairs;
pairs of e- not bonded to another atom
Linear shape:
2 atoms bonded and 0 lone pairs
trigonal planar shape:
3 atoms bonded and 0 lone pairs
tetrahedral shape:
4 atoms bonded and 0 lone pairs
trigonal pyramidal shape:
3 atoms bonded and 1 lone pair
bent
2 atoms bonded and 2 lone pairs
Lone pairs repel ->
more strongly that bonded pairs
Polar molecules:
dipoles
Determine polarity by:
looking for symmetry/ asymetry in lewis structure
Direction of the dipole is toward…
most electronegative atom
asymetrical=
polar
symetrical=
nonpolar
intermolecular forces:
forces of attraction that occur between molecules
Intramolecular forces:
forces of attraction that occur btwn atoms -covalent bond
Intermolecular forces are much _____ than the strong covalent bonds holding molecules together (intra)
weaker
Types of intermolecular forces:
-dipole-dipole interactions
-London Dispersion forces
-Hydrogen bonds
Hydrogen bonding:
bond btwn hydrogen and a more electronegative atom (O,N, F)
Dipole-Dipole Interactions:
attraction btwn opp charged regions (polar molecules) of neighboring molecules
London dispersion forces :
the weaker force cause by motion - momentary force
London disepersion force is the only force acting on….
nonpolar molecules and noble gases
Hydrogen bond is a special type of….
dipole-dipole force and is the strongest force
The strength of the hydrogen bond increases w/…
the degree of electronegativity of the atom bonded to it
