Chemical Bonds I Flashcards
Chemical Bonds
- Attraction between atoms or ions
2. Are due to the attraction between the positive nucleus and the negative electrons
Potential Energy
Stored in bonds between atoms/ions
Chemical Energy
Energy involved in making/breaking bonds
Energy Changes in Bonds
- When two atoms are bonded –> lower/stable potential energy level
- When stronger bonds form –> Exothermic Reaction + Less potential energy
Relationship between stabiltilty and potential energy
Inverse
Exothermic vs Endothermic
Exothermic: Stability is high, potential energy is low when compared to reactants
Endothermic: Stability is low, potential energy is high when compared to reactants
Endothermic/Exothermic Diagram
Bottom is potential energy
Top is kinetic energy
Electronegativity
0-.3 –> NPC
.3-1.7 exclusive –> PC
>1.7 inclusive –> I
Ionic Bonds
Attraction between ions
Nonmetal and Metal
Lewis Structures for Ionic Bonds
Must have charges
May draw arrows, or have nonmetal have a full shell
Properties of Ionic Compounds
As solids don't conduct electricity When melted/in aqueous solution conduct electricity High melting points Have crystalline lattice structure Very strong
Covalant Bonds
Either equally/unequally shared electrons
NPC
Shared equally between two nonmetals
END is
PC
Shared unequally between two nonmetallic atoms
.3
Properties of Covalant Compounds
Low melting Point
Dull
Brittle
Nonconductive
Network Solid
Chemical compound where the atoms are bonded covalently in a continuous network
Entire network is considered a molecule
Properties of Network Solids
Very high melting point
Very strong covalent bonds
Very hard
Not soluble in water
Examples of Network Solids
Diamond –> C
Silicon Dioxide –> Si02
Graphite –> C in two dimensional layers
Coordinate Covalent Bonds
When both electrons from a bond are shared by only one of the two atoms
Metallic Bonds
Electrons in solid metals are free travel atom to atom
Metals became cations due to loss of electrons
Attraction between the mobile electrons and the metals cause a strong bond to form
Called Sea of Electrons
Properties of Metallic bonds
Luster
Ductile
Malleable
Conductor
Localized Electron Model
Electron Pairs are assumed to be localized on a particular atom or in the space between two atoms.
Description of valence electron arrangement (Lewis Structure)
VSEPR
Description of atomic orbital types used to share electrons or hold lone pairs
Lone Pair Electrons
Electrons located on an atom
Bonding Electrons
Electrons found in the space between the atoms
2nd Row Elements
C,N,O,F use octet rule
Often have fewer than eight electrons, they are very reactive
3rd Row and heavier elements
Can exceed the octet rule, using empty d valence orbitals
VSEPR
Valence Shell Electron Pair Repulsion
Intramolecular
Involved in bringing atoms together to a compound
Ionic
Polar Covalent
Nonpolar Covalent
Intermolecular
Involved in bringing molecules together
Dipole-Dipole - Strong, Unequal/Partial charges
Hydrogen Bonds (H to F,O,N) - Strongest
Weak/Van Dar Waal’s - Weakest
Weak Intermolecular Forces
Small nonpolar molecules, best in liquid/solid phases with low temp and high pressure
Stronger when closer together
Smaller the molecule –> weak
Larger the molecule –> strong
Smaller nonpolar molecules, tend to be gases at room temperature, give them low boiling points –> Noble Gasses
Larger nonpolar molecules, tend to be liquids and solids at room temperature
Diatomic Molecules are also examples
