Unit 2 + 3 - Chemistry of Life and Water

polarity

an uneven distribution of electrons between oxygen and hydrogen

hydrogen bonds

a weak force/bond between the oppositely charged/polar water molecules

cohesion

attraction between molecules of the same substance

adhesion

attraction between molecules of different substances

capillary action

water climbing up a small tube because of the adhesion to the side and the cohesion between water molecules

High Specific Heat of Water?

water will absorb lots of heat energy with a minimal temperature increase

-enables water to act as a buffer/temperature control for land near water

High heat of vaporization for water

water will absorb lots of heat energy with minimal evaporation

Why does water expand when it freezes?

water forms a crystalline structure that expands and is less dense than its liquid state - it makes a fixed structure that creates relatively larger spaces between water molecules when compared to liquid water.

Why does water have a high surface tension? What is it?

the H-bonds hold the water together tightly, so the water's surface can act like a membrane

-many animals take advantage of this to 'walk' on water.

-the difficulty to break/stretch out a liquid. This is because the molecules at the surface can become closer together and thus have bonds that are harder to break

what is a mixture

a material that consists of 2 or ore elements or compounds physically but not chemically mixed together

what is a solution

a mixture where all the componets of a solution are evenly distributed throughout the solution

solute

the thing being dissolve

solvent

the thing doing the dissolving (think "water is the universal solvent"

How is acidity measured?

the concentration of H+ ions

how is alkalinity measured?

the concentration of OH-

What is causing ocean acidification/sketch out the graphic organizer?

1. excess CO2 put into the air is dissolved into the water, resulting in bicarbonate and hydrogen ions. This adds additional Hydrogen ions into the water

2. the bicarbonate further breaks down into more Hydrogen ions and carbonate. The increase of H+ into the ocean increases the H+ ion concentration, decreasing the pH, and increasing the acidity

Why is Ocean acidification an issue?

1. creating acidic environment where coral reefs are being destroyed. reefs are an important biome where many species take shelter, so the reduction places those species at risk

2. species like clams or crabs or animals at the bottom of the food chain that need calcium carbonate for their shells must now fight with the excess H+ ions for the carbonate necessary to build their shells. This leads to a reduction in feeder species(to which effects can be felt all the way up the food chain) and eventually poses problem/lack of food for human societies that rely on the ocean for protein

Extra things to do?

Answer the water chemistry question in the slideshow in notability.

What enables water to have life sustaining properties

Hydrogen bonding

What is hydrogen bonding

because of the strucutre of the H2O molecule and the fact the O2 is very electronegative, the water molecule its self is polar

-As a result, there are electrostatic attractions between the negative oxygen and positive Hydrogen between H2O molecules.

themral energy?

the KE associated w/ the random movement of atoms. Depends on volume

Temperature

the average KE of molecules, this is not dependent on volume

heat

transfer of thermal energy

evaporative cooling

surface under an evaporating liquid cools down because te liquid absorbs heat from the surface to have enough energy to break free and vaporize

How does water act as the universal solvent

-H2O is a polar molecule

-when it interacts with a salt, the respective positive and negative sides of H2O arrange with either the cation or anion of the salt and pull it apart creating hydration shells around the salt's ions

hydration shell

sphere of water around dissolved ions

what is a mol?

The amount of material containing 6.02* 10^(23)particles

AKA Avogrados number

what is a dalton

a measurement of how much a proton or nuetron weigh. Its the same as an AMU

how many daltons in a gram of substance

6.02x10^23 DALTONS in 1gram of substance

what is a buffer?

substance the minimizes the ∆ in [H+] or [OH-] in a solution

What is a buffer typically made up of?

a weak acid and it conjugate base or VV

matter

anything that takes up space and has mass

elements

substance that cannot chemically be further broken down

compound

substance that consists of two or more elements in a fixed ratio.

-A compound has different characteristics from just the elements alone

essential elements

elements that an organism needs to live + reproduce

trace elements

elements that are only needs in small quantities

atom

smallest unit of matter that retains the properties of an elements

protons

a positive particle w/ mass w/in the atomic nucleus (1 AMU or Dalton)

electron

a negative particle w/ little to no mass

nuetrons

particles with no charge within the atomic nucleus with an approximate mass of 1 AMU/Dalton

atomic number

number of protons in an atom

mass #

total # of proton + nuetrons

atomic mass

total mass of an atom

isotopes

atoms with the same # of protons and electrons, but with a dif number of nuetrons

radioactive isotopes?

sometimes, the nucleus will decay

-if the decay results in a loss of protons, the atom itself changes

-can also be used to track/fight cancer but also could lead to dangerous stuff like nuclear fallout

carbon-dating

A way for scientists to use carbon-14 remaining in fossils and half-lifes to determine how old something is

half-life

The time for a parent isotope to decay 50%

energy

the capacity to cause ∆

PE

the energy matter possesses due to its location/structure

-in an atom, the further from the nucleus, the more PE. In the same vein, e- can only move to spfc energy levels

Valence Electrons

e- in the outermost shell (valence shell)

Orbitals

3d space where e- are likely to be found

how many e- can be held in an orbital

2

what participates in chemical reactions

any unpaired electrons that are found in orbitals

chemical bond

attraction b/w atoms via shared or transfered electrons

covalent bond

a pair of VE shared b/2 two atoms

molecule

2 or more atoms held together via covalent bonds

valence

the bonding capacity of an element (ie the # of unpaired electrons)

electronegativity

attraction of an atom from e

non-polar covalent bond

EN are the same and e- are evenly shared

polar covalent

e- are not shared equally and the resulting molecules thus has polarity

ions

charge atoms

cation

positive ion

anion

negative ion

ionic bond

attraction between a cation and anion

-they are held in a lattice

-and are weaker in aqueous soltions

how strong are H-bonds

WEAK

how does shape affect molecules?

the shape dictates its ability to be recognized and respond to

-this is partially why structure and function are so important

vander waals interactions

weak attractions b/2 atoms/moleculs due to uneven e- distribtion in molecules

What are the life-sustaining properties of water

1. adhesion + Cohesion

2. capilary actions

3. ice floats in water

4. high heat of vaporization and high specific heat

5. universal solvent

6. surface tension