2.2 water Flashcards
ion
an atom with a + or - charge due to unequal amount of e- and protons
Polar molecule
A molecule exhibiting seperation of charge due to unequal distribution of e-
Isotope
Atoms with same amount of e- and protons, but different neutrons
Water molecules
Are polar, Oxygen has slightly more negative chareg due to its size
Have covalent bonds, share e-
Dipolar molecule
Have hydrogen bonds between the hydrogen and oxygen (ONLY WHEN H2O binds to another H20)
Can form 4 hydrohen bonds (2 O2 & 2 H)
Cohesive and adhesive properties of water
Hydrogen bonds allow water to be cohesive (sticks to same molecule)
Water is adhesive (it can stick to other polar or ionic substances)
Cohesion allows water to flow up the xylem of plants against gravity due to cappilary action while adhesion adheers water to xylem
Thermal properties of water
Has a high specific heat capacity (High energy to break hydrogen bonds)
Has a high latent heat of vapourizastion (Liquid to a gas)
Water as a coolant
When water evaporates it removes a lot of energy from the system (Sweat)
Comparison of thermal properties of water to methane
Higher heat of vaporization
Higher melting and boiling point
Higher specific heat capacity
Higher heat of fusion (Liquid to solid)
Methane has no hydrohen bonds
Hydrophilic and hydrophobic substances
Phospholipid bilayer:
Phospahte head is hydrophilic
Fatty acid tail is hydrophobic
Amphipathic = have both hydrophilic and hydrophobic properties (soap)
Solvent properties of water
Solvent = Dissolving something
Is a good solvent because it is a polar molecule
Can dissolve polar solutes easily
Ionic solids dissociate in water (Salt NaCl):
Negative O2 side of water attracts to Na+
Positive H attract to Cl-