Unit 2 Flashcards
(46 cards)
Why do chemical bonds occur?
The particles have a lower potential energy bonded to eachother than they do separately
What are the forces between two molecules called and the forces acting within a molecule called?
Between two molecules- intermolecular
Within molecule- intramolecular
What does a higher boiling/melting point do to a molecules intermolecular forces?
They get stronger
Are intramolecular forces affected by physical changes such as adding heat?
No
What are the four categories chemical bonds can be separated into?
Nonpolar-covalent
Polar-covalent
Ionic
Metallic
What are nonpolar covalent bonds? What must the electronegativity difference be?
Occurs when two atoms have similar electronegativity values and share valence electrons
Non polar bond is when the electrons are shared equally
Electronegativity difference must be between 0 and 0.4
What are polar covalent bonds? What is their electronegativity difference?
Means that there are charged ends to a molecule
They share valence electrons but not equally
Electronegativity difference between 0.5 and 1.7
What are ionic bonds? What is their electronegativity difference?
They are so polar that electrons are transferred from one atom to another
Oppositely charged particles attack eachother
Formed between anions and cations
Electronegativity difference of 1.8 or higher
What are metallic bonds?
Formed between metal atoms
Do not follow octet rule
S and P orbitals overlap allowing electrons to move freely and be good conductors of heat
What is bond energy?
Energy required to break a bond to form neutral atoms
What is hybridization?
Hybrid orbitals are orbitals of equal energy produced by combining 2 or more orbitals on the same atom
What’s the difference between ionic and molecular compounds?
Molecular- made of non metals
Ionic- metals and non metals
What are sigma and pi bonds?
When hybrid orbitals make bonds, they can be labeled as sigma or pi bonds
The first bonds always sigma bonds and are covalent bonds and can rotate
If there’s double or triple bonds the second and third bonds are called pi bonds made from leftover unhybridized p orbitals
What is bond energy measured in?
kJ/mol
What is Lattice energy?
The energy released when 1 mole of ionic crystalline compound is formed from gaseous ions
Difference between lattice energy and bond energy
Bond energy is for molecules (n+n)
Lattice energy is for ions (m+n)
What is he order of bond strength weakest to strongest of these intermolecular bonds: Ionic bonding Dipole-dipole Covalent bonding Hydrogen bonding London dispersion Metallic bonding
- London dispersion
- Dipole dipole
- Hydrogen bonding
- Ionic bonding
- Metallic bonding
- Covalent bonding
What part of matter are inter molecular forces responsible for?
The bull properties of the whole substance not the individuals that make it
Surface tension, capillary action and Viscosity
What is London dispersion forces?
Example?
Weak attractive forces cause by instantaneous dipoles when electrons happen to end up on the same side of a molecule
This bond happens in all atoms and molecules even noble gases
Ex: h^2
O^2
Cl^2
Br^2
What are dipole dipole forces?
Example?
Occur between 2 polar molecules. They are the strongest out of the three intermolecular forces but are very weak compared to ionic and Metallic bonds
Ex: HCl
What are hydrogen bonding forces?
Examples?
Strong category or dipole-dipole forces.
Only occurs in H-F, H-O, and H-N bonds
The high difference in electronegativity between H and F,O,N makes very polar molecules and positive H is attracted to negative end of another molecule
Which is more dense? Solids or liquids?
Solids
What are the four types of crystals?
- Ionic crystals
- Covalent network crystals
- Covalent molecular crystals
- Metallic crystals
What are ionic crystals?
Composed of negative and positive ions
Are hard, brittle, good insulators, and have high melting points
