CHEMICAL interactions
weak chemical interactions (3 types) are?
- ionic bonds
- hydrogen bonds
- van der Waals interactions
properties of water are due to the
shape of H2O and hydrogen bonding
adhesion IS ___?
molecules that stick to other kinds of molecules - also an important property of water
water has to absorb or ..? an example?
lose a large quantity of heat for each degree of temp change - resists changing temperatures
- also: - water’s specific heat is much higher than other substances
- when put a pot of water on a hot stove, the pot gets hotter faster than the water
pH is a measure of...?
the amount of Hydrogen ions (H+) in a solution.
VAN DER WAALS interactions only occur when...? and they lead to what?
Occur when atoms are close together; lead to always changing regions of + and – charge b/c e- not evenly distributed
H bonds ______ H2O molecules are super important
between
water resists...? because of what?
resists changing temperature – it can absorb (take in) and lose (give off) a lot of heat without itself changing temperature - because of H BONDS
H BONDING IN TEMP OF WATER DOES WHAT WITH HEAT?
a lot of heat must be absorbed to break H bonds before temp increases à resists increasing temperature (HINT: THINK OFPOT ON STOVE)
dissociation is when...? is it rare?
H2O molecules sometimes break apart; yes, rare
van der Waals interactions are individually...?
WEAK; but together simultaneous interactions = strong
emergent properties of water are? (4)
1. water is cohesive (it “sticks” to itself through H bonds)
2. water maintains a relatively stable temperature
3. water expands when it freezes
4. water is a good solvent (substances dissolve in water)
temperature measures the...?
the movement of atoms/molecules - atoms and molecules are ALWAYS moving
§ higher temperature = faster movement
§ lower temperature = slower movement
molecules moving fast enough can leave the liquid state and become a...?
gas---> called vaporization, or evaporation
H2O characteristics in the role of acids and bases and pH?
H detaches from one H2O and attaches to another H2O § (due to random electrical changes within atoms)
§ H brings a proton and leaves an e-
hydronium ions (H3O+) and hydroxide ions (OH- ) form
STRONGEST TO WEAKEST BONDING ORDER?
non-polar covalent, polar covalent, ionic, hydrogen bonds, van der waals
H2O molecules stick to..? b/c of...?
THEMSELVES - COHESION
HEAT IS the transfer of...?
heat is transferred from a..?
- of energy from a higher temperature to a lower temperature
- warmer to a cooler object à molecules in the cooler object speed up
water has a high heat of...?
vaporization - the amount of heat needed to change a substance from liquid to gas
- takes a lot of heat for water to vaporize due to the energy needed to break H bonds
dissociation reaction is ...? B/C..?
REVERSIBLE; H+ and OH- concentrations are equal in pure water
s and p orbitals combine to form four new
TEARDROP OR TETRAHEDRON SHAPE
cohesion leads to high...? which is?
surface tension – a measure of how hard it is to stretch or break the surface of a liquid
e.g. spider walking across pond
specific heat is ...?
– a measure of how much heat a substance must absorb in order to change temperature
evaporative cooling happens b/c ...?
molecules moving the fastest leave as a gas – they take heat with them
what is an acid verus a base?
an acid = increases H+ concentration of a solution; when acids dissolve in water, they donate additional H+ to the solution
a base = a substance that reduces H+ concentration of a solution; when bases dissolve in water, they may either:
1) attract and bond with H+, or 2) they may donate OH-