CHAPTER 4 Flashcards
A ____ is a two-electron bond in which the bonding atoms share valence electrons.
covalent bond
A ___ is a compound held together by covalent bonds.
molecule
These electron-dot structures for molecules are called:
Lewis structures
This show the location of all valence electrons in a molecule, both the shared electrons in bonds, and the nonbonded electron pairs.
Lewis structures
Exceptions to the octet rule
Hydrogen
Boron
Phosphorus
Sulfur
These are two or more Lewis structures having the same arrangement of atoms but a different arrangement of electrons.
Resonance structures
An atom surrounded by four groups is tetrahedral and has bond angles of __.
109.5°
An atom surrounded by three groups is trigonal planar and has bond angles of ___.
120°
It is used for bonds in the plane.
solid line
It is used for a bond in front of the plane.
wedge
It is used for a bond behind the plane.
dashed wedge
A n atom surrounded by two groups is linear and has a bond angle of ___.
180°
It is a measure of an atom’s attraction for electrons in a bond. This tells us how much a particular atom “wants” electrons.
Electronegativity
These are used as a guideline to indicate whether the electrons in a bond are equally shared or unequally shared between two atoms.
Electronegativity values
Is carbon-carbon bond nonpolar or polar?
Nonpolar
Periodic table:
Left to right—increasing electronegativity: yes or no?
Yes
Periodic table:
Up to down—increasing electronegativity: yes or no?
No; it’s down to up
Bond type: Electrons are equally shared.
Nonpolar
Bond type: Electrons are unequally shared; they are pulled toward the more electronegative element.
Polar
Bond type: Electrons are transferred from the less electronegative element to the more electronegative element.
Ionic
Less than 0.5 unit
Nonpolar
0.5-1.9 units
Polar
1.9 to up
Ionic
A molecule with no polar bonds is a ___ molecule.
nonpolar
