Test 9/26/16 Flashcards
Explain what it means when we say water has a high specific heat
- The amount of heat that must be absorbed or lost to change 1g of the substance by 1°C
- Water has a higher specific heat than many water substances
State 4 ways in which waters high specific heat impacts life on Earth
- oceans store heat, making coastal environment milder
- stabilize ocean temps
- keeps earths temp within reasonable range
- helps organisms resist temp changes
Explain how evaporative cooling is important to life.
- helps moderate earths climate
- stability of temp in lakes and ponds
- prevents land organisms from overheating (sweat on skin) (water evaporating from plants)
- high humidity= decreased evaporative rate
Describe what happens to water when it freezes. How is this important to life in earth?
- H-Bonds B/w water molecules stabilize causing a crystalline structure
- ice is less dense than liquid water and floats
- insulates lakes and ponds(prevents them from freezing through)
Solute
Substance being dissolved
Solvent
Dissolving agent
Solution
Homogenous mixture of solute and solvent
Know how water dissolves an ionic compound such as NaCl
Ok
Describe how even large proteins become dissolved by water
Large proteins can have areas of positive and negative charge which affects water
Hydrophilic
Attraction for water
What is an example of hydrophilic
Cotton/cellulose
Hydrophobic
Repels water
Examples of hydrophobic
Non ionic and non poor molecules oils
Water is dissociated into what 2 components? Give the equation.
H2O—> H(+) + OH(-)
Describe a basic solution
More hydroxide (OH-)
Describe an acidic solution
More hydrogen (H+)
What percentage of water are cells?
70%-95%
What amount of earths surface is submerged in water?
3/4
___% of earths water is saltwater
97
____% of freshwater is locked in ice caps
70
____% of earths freshwater is accessible
Less than 1
What are the three physical states of matter
Solid and liquid and gas
Polarity
The uneven distribution of charge in a molecule
What are the four emergent properties of water?
- waters cohesive behavior
- its ability to moderate behavior
- its expansion upon freezing
- its versatility as a solvent
Cohesion
The binding together of like molecules often by hydrogen bonds
Adhesion
The attraction between different kinds of molecules
Capillary action
As water evaporates from a leaf, the H-Bonds between water molecules allow for the water lower in the plant to be pulled upward
Surface tension
A measure of how difficult it it to stretch or break the surface of a liquid
Water has a ______surface tension than most other liquids
Greater
Element
A substance that cannot be broken down to other substances by chemical reaction
Compounds
A substance consisting of two or more different elements
How many natural elements?
92
How many elements are easential for life?
25
How many elements make up 96% of all living matter? What are they?
4//C, H, O, N
Trace elements
Elements required by an organism in small quantities
What are examples of trace elements?
Iron, Iodine, Fluorine
Where are protons and neutrons found?
In the nucleus of an atom
Proton
Positive
Neutron
Neutral
Where do electrons travel
Around the nucleus in orbit
Electron
Negative
Atomic #
Number of protons
Mass #
Sum or protons plus neutrons
Atomic weight/mass
An approx of the total mass of an atom
Valence
The outer electron shell that they travel in
Isotopes
Atoms that have more neutrons than other atoms of the same element
Isotopes can be ______________
Stable or radioactive
How are radioactive isotopes useful?
Traces thru metabolic pathways and diagnostic tools for cancer
-they are picked up by cells just like other isotopes but they can be detected by equipment
An atom with a full valence shell is _________________
Unreactive and will not readily interact with other atoms
Incomplete valence shells=??
Chemically reactive
What is a nonpolar covalent bond?
A bond formed what two atoms are equally electronegative and thus equally share electrons
Examples of non polar covalent bonds
H2 and 02
What is a polar covalent bond?
A bond formed when one atom is more electronegative than the other thus pulling the shared electron more to itself. Results in partial charges thru the molecule.
Give 2 examples and describe the relative strength of their polarity
Methane//Water
-methane is slightly polar because C and H differ slightly in electronegativity. Water has strong polarity because oxygen is much more electronegative than Hydrogen
What is an ionic bond?
A bond formed when two 2 atoms have an unequal attraction for valence electrons. The more electronegative atom strips the E- from the other atom. The bond is formed because of the attraction B/w the now oppositely charged ions.
What 2 ways are weak binding important?
- Important late biological molecules are held in their functional form by weak bonds
- Weak bonds are very reversible which allows two molecules to come together, respond, and then separate
Explain how hydrogen bonds form
Hydrogen bonds form when a H is covalently bonded to an atom and is also attracted to another electronegative atom. The H of a water molecule will be attracted to the O of an adjacent water molecule.
Explain Van der Walls interaction
Occur B/w atoms and molecule that are very close together and “hot spots” of electronegativity occur randomly based on the spontaneous travel of the electrons through their orbitals.
How does shape influence function?
Molecular shape determines how molecules recognize and respond to one another with specificity. Only molecules with conplementary shapes are able to bind to each other by weak bonds
Describe the specific example of pain relief
Natural endorphins born with receptors in the brain producing pain relief. Morphine, heroine are similar in shape and will bind the same receptors thus having the same effect
What is the chemical equation for photosynthesis?
6CO2 + 6H2O —-> C6H12O6 + 6O2
Explain how the concentration of the reactant affects the rate of the reaction
The higher the concentration of reactants l, the more collisions accuse which speeds up chemical reactions.
How is chemical equilibrium reached?
When the rate at which products are being formed is equal to the rate at which the reactants are being formed.
Cation
Positive ion
Anion
Negative ion
Chemical bonds
Attraction that holds molecules together. Involves valence electrons
Which has the strongest bond?
Ionic
Which has the weakest bond?
Hydrogen
