2.2 Water Flashcards

1
Q

Structure of Water

A

H2O
2 hydrogen atoms = oxygen atom
covalently bonded

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2
Q

Covalent bonding of H2O described

A

Unequal sharing of electrons between atoms.
Oxygen has higher electronegativity = which attracts electrons more strongly.
Shared electrons orbit closer to oxygen

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3
Q

Polarity

A

How different the electrical poles of a molecule are

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4
Q

Polarity of water

A

Polar; oxygen atom is negative, hydrogen atoms are slightly postive
Charge difference is Dipole

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5
Q

Water polarity purpose

A

Charge difference (dipole) allows water to form weak associations with other polar molecules
(neg poles attract pos poles, etc.)

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6
Q

Hydrogen bond

A

When a (+)hydrogen atom is a attracted to a (-)fluorine, oxygen or nitrogen

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7
Q

Covalent bond

A

Formed by equal sharing of electrons from both atoms

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8
Q

Purpose of dipolairty of water molecule

A

enables it to form polar associations with other charged molecules (polar or ionic)

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9
Q

Hydrogen bonding of water

A

Water can form hydrogen bonds with other water molecules

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10
Q

Properties of water

A
  1. Thermal properties
  2. Cohesive / adhesive properties
  3. Solvent properties
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11
Q

How water has its unique properties

A

This intermolecular bonding between water. Not seen in other substances

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12
Q

Thermal properties of water

A

Can absorb a lot of heat before changing state
Requires breaking of hydrogen bonds

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13
Q

Cohesive / adhesive properties

A

Water sticks to other water molecules (cohesion) and charged substances (adhesion)

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14
Q

Reason of water’s thermal property

A
  • Extensive hydrogen bonding of water molecules
  • H-bonds nees to be broken before state change, requires absorption of energy (heat)
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15
Q

Compare methane to water

A
  • Similar structures, in size & weight
  • Comparable valence structures
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16
Q

The function of water’s polarity

A

polar property attracts other molecules that are polar or have an ionic charge

17
Q

Cohesion

A

Ability of like molecules to stick together

18
Q

Adhesion

A

ability of dissimilar molecules to stick together

19
Q

Cohesion of water

A

strongly cohesive (forms hydrogen bonds)

20
Q

Adhesion of water

A

Water will form intermolecular associations with polar and charged molecules

21
Q

Significance of cohesive properties of water

A

Explains surface tension

22
Q

Explain surface tension

A

H-bonds between water molecules resist low levels of external force (surface tension)

23
Q

How smaller organisms move across the water surface

A

high surface tension; sufficiently dense enough to support the creature

24
Q

Significance of adhesive properties

A

Explains capillary action

25
Explain Capillary action
Attraction to charged / polar surfaces allows water to flow in opposition to gravitational forces
26
Capillary action
Water flowing in opposition of gravitational forces
27
Purpose of capillary action
Allows water to be transported up plant stems via a transpiration stream
28
Universal solvent
water; capacity to dissolve large number of subtances
29
What can water dissolve
substances containing ions (charged particles) or polarity (electronegative atoms)
30
How water solvency occurs
1. Polar attraction of large quantities of water weakens intramolecular forces(ionic bonds) 2. --> dissociation of atoms 3. Slightly charged regions of water molecules surround atoms of opposing charge 4. Dispersive hydration shells form
31
Substances' reaction to water
Can be hydrophilic or hydrophobic
32
Hydrophilic
'Water Loving' Freely associate + readily dissolve in water
33
Hydrophobic
'Water Hating' Don't freely associate / readily dissolve in water
34
Examples of hydrophobic subtances
Large, non-polar molecules (e.g. fats, oils,...)
35
Purpose of water solubility
Transport of essential molecules within the bloodstream depends on water solubility
36
Transport of molecules in the bloodstream
Water soluble = travel freely in blood plasma Water insoluble = cannot travel freely
37
Examples of water-soluble substances
Sodium chloride Oxygen Glucose Amino acids
38
Examples of water-insoluble substances
Lipids Proteins Cholesterol
39
How lipids move through bloodstream
Non-polar and hydrophobic Form complexes with proteins (lipoproteins) to move through bloodstreams