Test 3 Definitions Flashcards
Ionic Bonds
Ionic bonds occur when the atoms of one element lose valence electrons, while another element gains valence electrons. (Transfer of valence electrons drawn by electrostatic attraction)
Covalent Bonds
Covalent bonds occur when non-metal atoms share electrons to attain a noble gas arrangement. (Sharing of electrons)
Octet Rule
Stable ions and stable atoms in a bond have a full outer shell; this means for row 2 and on, atoms/ions need access to 8 electrons. Exception: Hydrogen needs access to 2
Shapes of Molecules: What does molecular geometry include?
Lone pairs need space, just as bonds do. Molecular geometry only includes the atoms and the bonds.
Shapes of molecules: 2 pairs, 0 Lone
Linear
Shapes of molecules: 3 pairs, 0 lone
Trigonal Planar
Shapes of molecules: 2 pairs, 1 lone
Bent
Shapes of molecules: 4 pairs, 0 lone
Tetrahedral
Shapes of molecules: 3 pairs, 1 lone
Trigonal Pyramidal
Shapes of molecules: 2 pairs, 2 lone
Bent
Polar Bonds
Polar bonds are formed when two atoms share a pair of electrons (covalent bond), but one of the two atoms has a greater attraction for electrons. They are more likely to be found closer to that nucleus. Which now has a higher density.
Electronegativity > 1.8
Ionic
Electronegativity < 0.5
Non-polar
Electronegativity <= 0.5 - >= 1.8
Polar
Electronegativity
measures the tendency of an atom to attract a bonding pair of electrons (based on experimental data)
Dipole-Dipole Attractions
Polar Molecules. The partial positive part of one molecule is attracted to the partial negative part of a neighbor.
What is the direction of polarity?
Positive to Negative
When is hydrogen bonding possible?
When hydrogen is bonded to Nitrogen, Oxygen, or Fluorine
Can Acetone bond with itself? O = C – CH3 – CH3
No. There is hydrogen on carbon, but not on Nitrogen, oxygen, or fluorine
Order of increasing force: Hydrogen bonding, covalent bonds, dispersion forces, and dipole-dipole forces
(Lowest Force) Dispersion Forces, Dipole- Dipole, Hydrogen Bonding, Covalent Bonds (Highest Force)
What are 4 effects of water having hydrogen bonding?
A high melting point, a large liquid range, a very high boiling point, and surface tension (helps dissolve) ALSO, ice floats
Effects of intermolecular attraction?
- Stronger molecular forces bring molecules together, creating a condensed phase like liquid or solid (molecules have to overcome intermolecular interactions to transition between solid, liquid, and gas)
- Stronger intermolecular forces demand more energy (heat) to transition from solid, liquid, and gas).
- In liquids, molecular attractions cause viscosity and surface tension
