chapter 8 Flashcards
covalent bonds are a
sharing of electrons that form molecules
covalent bonds…
share electrons and involves only nonmetals
Compounds that are bonded covalently are called
molecular compounds
molecular compounds have
lower melting and boiling points than ionic
molecular compounds tend to be
gases or liquids at room temperature
molecular formula
Shows how many atoms of each element a molecule contains
double bond
is when atoms share two pairs of electrons (4 total)
triple bond
is when atoms share three pairs of electrons (6 total)
Bond Dissociation Energies…
The total energy required to break the bond between 2 covalently bonded atoms
High dissociation energy usually means
the chemical is relatively unreactive, because it takes a lot of energy to break it down.
Resonance is…
When more than one valid dot diagram is possible
The 3 Exceptions to Octet rule
- odd number of valence electrons
- boron and berillyum
- in period 3 or beyond
sigma bond
when two atomic orbitals combine to form the molecular orbital that is symmetrical along the axis connecting the nuclei
pi bond
the bonding electrons are likely to be found above and below the bond axis (weaker than sigma)
shared evenly
nonpolar covalent bond
shared unevenly
polar covalent
electronegativity increases
as you go up and to the right
diatomic defeniton
made of two atoms
which atoms are diatomic?
Hydrogen, nitrogen, fluorine, oxygen, iodine, chlorine, bromine
Have no fear of ice cold beer
Bond lent:
distance between 2 atoms where sharing is optimal and repulsion between two nuclei is negligible
how to draw lewis structures
- Count number of valence electrons
- First element listed is central element, carbon always and hydrogen never
- Draw single bonds
- Assign remaining electrons to outside atoms first until octet then the central
- Check for octet and draw double or triple bonds as needed/resonance
extended octet:
element has more than 8 electrons in lewis structure, only possible for elements period 3 and down, because they have available d’orbitals
intramolecular bonds:
bonds within molecule (polar/nonplar)
intermolecular bonds:
bonds between 2 molecules
dipole-dipole
between 2 polar bonds
LDF
between 2 nonpolar bonds
H-bond
bond must have H-O, H-N, H-F
bonds strongest to weakest
hydrogen bond
dipole
ldf
in large amount ldf can be stronger than dipole
structural formula
chemical formula that shows the arrangement of atoms in molecules and polyatomic ions
dispersion force
interaction caused y the motion of electrons
network solid
substance in which all of the atoms are covalently bonded to each other
coordinate covalent bond
a covalent bond in which the shared electron pair comes from only one of the atoms
bonding orbital
molecular orbital that can be occupied by two electrons of a covalent bond
sigma bond
symmetrical bond along the axis between the two nuclei
VSEPR theory
shapes adjust so valence-electron pairs are as far apart as possible
network solid
crystal in which all the atoms are covalently bonded to each other
How do atoms achieve noble-gas electron configurations in single covalent bonds?
Two atoms share two electrons.
