Review:
Chapter one was on overview of what ES is all about, what your greatest challenges will be in this century (good luck), and some bits about the scientific method (and how to find witches).
The iBook covered these as well, but in a more interactive overview.
Chapter two is all about systems, matter and energy, the subject of other courses as well: physics is all about energy and matter, chemistry is about matter and reactions, and biology includes feedback loops and systems.
For this chapter, cause and effect will be your guide-keep these in mind.
Reading: Chapter 2 in FR text, modules 4 and 5. Module 4 is huge, so don't give up.
Module 4: Systems and matter----------
matter=takes up space and has mass (better definition: anything that has density since d = m/v)
mass=amount of matter (n.b. NOT weight, you can be weightless in orbit, but you still have mass-watch the film Gravity...)
atom: a=not, tom=cut (look up tomogram, or go to subway)
atom=smallest particle (known then) that cannot be cut further (we now know there are protons, neutrons, electrons, and quarks, even smaller things than these are predicted, look up string theory)
Element: recall all of your previous science courses-this is a collection of atoms that share the same identity, usually noted on the periodic table by their number of protons, NOT neutrons (e.g. isotopes) or electrons (e.g. ions)
Look at carbon 12, 13 and 14-look at the notation for each (isotopes=iso, same tope, type)
Look at sodium atom and sodium ion, note the notation for each
Why do they have certain charges? Who does every element "want" to be? Why?
Diverge here into orbitals if you like; s,p,d,f (sharp, principal, diffuse and fundamental spectral lines)
Molecules: more than one atom (H2)
Compound: more than one element (NaCl)
Radioactivity: unstable nucleus (usually more neutrons than protons), releases particles (often neutrons, but includes electrons as beta rays, or energy as gamma rays)
Largest and slowest radiation is alpha rays: slow Helium nuclei (2 protons, 2 neutrons, no electrons, so they are + charged)
Radiation summary:
alpha rays: Helium nuclei, slow, charged, stopped by your skin or paper
beta rays: fast electrons (137,000 mph), charged, stopped by foil
gamma rays: fast photons with very high energy, penetrates almost everything, stopped by lead
neutrons: can be fast (bad) or slow (thermal, useful in creating steam in nuclear power plants), goes through everything but 2 meters of concrete
Half life: not just a boring Saturday night
Time it takes for half of whatever to decay, depends on amount left, like water leaking from a large water tank
If you are into math, this is known as a differential equation, meaning the rate is dependent on the amount left. We'll see more of this in population curves, but any time a rate is dependent on how many there are, you'll see the half life rear it's head.
Lab: M&Ms® (Thursday)
quiz 8.28.19
- What is similar and/or different between U 234/92 and U 238/92?
- How many protons, neutrons and electrons in each?
- Would you expect this to be radioactive?
- A news announcer says:”Iodine 131 has a half life of 8 days, so it will all be gone in just 16 days”. What is wrong with this?
-----8.27.19---------------------------
Bonds: (not the money kind)
Covalent: weak, think of plastic, butter or things that can melt. Electron is shared between both atoms (e.g. pilot copilot)
examples: any twin (H2)
Ionic: strong, electron moves from one atom to another (NaCl is a good example), hard to melt, usually dissolves in water
Polar molecule: has one end more + than the other (like water, which is polar covalent-confusing!)
Surface tension: cohesion (holding hands)-think of water bugs, and the soap example
Soap makes water "wetter" by reducing surface tension between water molecules
It also has an ionic (water loving, hydrophilic) side and a covalent (water hating, hydrophobic) side, so it can carry away oils
Capillary action: cohesion and adhesion (think of adhesive)
Key to all plants...
Colligative properties (collected properties): bp (boiling point), fp (freezing point), mp (melting point, often the same as fp)
Can be influenced by other substances, e.g. antifreeze, which is ethylene glycol, an alcohol. You could use any alcohol in your car to raise the boiling point, but ethylene glycol is less flammable (yet toxic to animals) than ethanol
n.b. anything that ends in -ol is an alcohol: methanol, ethanol, butanol, propanol, etc.
You could also use salt, which is hard on the guts of car engines, but is great for melting ice on roads, or making ice cream (freezing point depression)
Water is weird stuff: as it boils, it gets less dense (e.g. steam) AND when it freezes, it gets less dense (e.g. ice)
Why is this critical for lakes in the winter?
It is also a "universal solvent" since it has pH of 7, dissolves ionics and is polar covalent. Nice to drink as well.
Acid: more Hydrogen ions free (H+)
Base: fewer Hydrogen ions free (more OH-)
Water: amphoteric (both sides): balanced H+ and OH-
Water is H-O-H or H-OH, so has a balance
----8.28.19--------------
quiz 8.29.19
- what is the connection between water striders, tall trees, premature babies and vaping?
- what is the connection between wifi, microwave ovens and dry toast?
On alcohol being used as food for alcoholics:
Ethanol is metabolized in the body into ethanoic acid also known as acetic acid. You bio folks may recognize this as one of the inputs in the TCA (citric acid or Krebs) cycle. Once a human body "learns" how to live off of ethanol (e.g. alcoholics), many of their calories come from this source. One theory uses this as a possible explanation for certain genetic predispositions towards alcohol dependence.
This is what the chemistry looks like:
C-C-OH ---> C-C-O-O-H ---->C-C-H-O
ethanol --> ethanoic acid --> ethanal
The other name for ethanal is acetaldehyde, which is the strange smell you detect coming off the breath and skin of alcohol drinkers.
Methanol takes a far more toxic path:
C-OH --->C-OOH ----> C-HO
methanol --->methanoic (formic) acid ---> formaldehyde
You might recognize the second one as the sting from fire ants, and the third as something they embalm dead bodies in...
--------back to pH------
pH: n.b. the notation, this means "potency of H+ ions" (don't misspell it)
------Thursday 8.29.19----m&m lab
AP Environmental Science
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