8.1 & 8.2 Flashcards
molecule
most basic unit of a covalent compound and also any 2(+) atoms held together by covalent bonds
monoatomic
exists in nature as a single atoms
what are the 7 diatomic elements?
I, H, N, B, O, Cl, F
covalent bonds are made between ____ atoms
non metal
are covalent bonds conductors of electricity at any state?
NO
molecular formula
tells you the elements in the compound and the number of each type of atom in the molecule
structural formula
tells you the elements in the compound and the number or each type of atom in the molecule AND the arrangement of atoms and bonds
isomer
compounds that have the same chemical formula but different structures
molecule is to ____ where structural formula is to ___
roster, seating chart
the representative unit of a molecular/covalent compound is a ____
molecule
the representative unit for an ionic compound is ___
formula unit
molecule ____ break apart when compound melts, boils, or dissolves
DOESNT
formula units ___ break apart into ions when melted or dissolved
DO
molecular compounds have a ____ melting point
low
ionic compounds have a ____ melting point
high
molecular compounds have a ___ boiling point
low
ionic compounds have a ____ boiling point
high
molecular compounds are ___ at room temp
gases or liquids
ionic compounds are ___ at room temp
solids
molecular compounds are made of ___
2(+) nonmetals
ionic compounds are made of ___
metals combined with nonmetals
in molecular compounds molecules act ___
as one unit
in ionic compounds the ions ___
done act as one unit; continuous array of ions
the most number of bonds that can form between any 2 atoms is ___
3
elements that are in the period 3 or high can do what?
can make expanded octets they can have 10 or 12 valence e-
what are the usual exceptions to the octet rule?
phosphorus , sulfur, and iodine
___ can make compounds/form bonds even though its a noble gas
xenon
____ is happy with just 6e- around it instead of 8
boron
covalent bond
when 2 atoms share 1(+) pairs of e-
resonance structures
two or more valid electron dot formulas that can be written for the same molecule
van der waals forces
the weakest attractions that exist between molecules
polar molecule
a molecule in which one end is slightly negative and the other end is slightly positive
polar covalent bond
a covalent bond formed between two different atoms in which the bonding electrons are shared unequally
coordinate covalent bond
a covalent bond in which ones atom contributes both bonding electrons
how to name a covalent compound
- greek prefix for 1st element (aslong as its not 1)
- name of first element
- greek prefix for 2nd element
- root of 2nd element
- change sufix of 2nd element to “ide”
polyatomic atom
an ion that is made of many atoms and a group of covalently bonded atoms that have an overall charge and also are a tightly bonded group of atoms made up of covalent and coordinate covalent bonds
polyatomic ions form ___ bonds with other ions
ionic
bond dissociation energies
the amount of energy required to break 1 mole of the bond
the greater the bond energy the more…
more stable the bond
the greater the bond energy…
the more stable the bond
rank the bonds shortest to longest
triple, double, single
for a chemical reaction to happen…
you have to break bonds in the reactants are make bonds in the products
breaking bonds =
endothermic (takes energy in)
making bonds =
exothermic (releasing energy)
bonds between the same element are always …
nonpolar
electronegativity
measure of how strongly an atom attracts e- in a bond
polar covalent bonds happen when…
electrons are shared unequally
water is a polar molecule because…
oxygen is more electronegative than hydrogen, so the electrons are pulled closer to oxygen
oxygen is slightly…
negative
hydrogen is slightly…
positive
EN increases across a …
period
EN decreases down a…
group
level of bond polarity is determined by what?
the EN difference between bonding atoms
sigma negative
the atom that has the higher EN
sigma positive
the atom that has the lower EN
0.0-0.4 =
nonpolar covalent
0.5-1.0=
moderately polar covalent
1.1-2.0=
very polar covalent
greater than 2.0=
ionic
dipole
molecule has positive and negative poles that align between charges plates.
intra covalent attraction
stronger and hold the compound together
intermolecular attractions
weaker, hold particles together
dipole interactions
attractions between polar molecules
dispersion forces
induced or momentary dipoles due to e- in molecules temporarily shifting in one molecule
what do you need to add to break intermolecular attraction?
heat
properties of components/elements depend on what?
IMF (intermolecular forces) and are melting/boiling points, solubility, evaporations
london dispersion forces
(LDF) the weakest of all molecular interactions which is caused by the random motion of electrons
what is the only type of IMF in nonpolar substances?
LDF
LDF happens b/c…
electrons dont want to be near anthoer electron
more electrons in an atom/molecule =
more dispersion forces
higher molecules =
more e- = higher LDF
