Transcript Chapter 2 Science, Matter & Energy Janice Padula Clinton Community College

Chapter 2
Science, Matter & Energy
Janice Padula
Clinton Community College
Scientific Method:
• EXPERIMENT - An observation of natural phenomena
carried out in a controlled manner so that the results can be
recorded, duplicated, and rational conclusions obtained.
• HYPOTHESIS - A tentative (unconfirmed) explanation of
or prediction derived from experimental observations.
• MODEL – An approximation or simulation of a hypothesis
or system being studied.
• THEORY - A tested and widely accepted explanation of
basic natural phenomena or scientific hypothesis.
• LAW - A concise verbal or mathematical statement that is
always the same under the same natural or controlled
conditions.
Validity of Results
• Scientific Results (reputable scientific research)
– Can be disproved
– Can establish models theories and laws
– Can NOT prove absolute truth
• Frontier Science (like media reports)
– Controversial
– Not widely tested or accepted
• Consensus Science (open peer review)
– Widely accepted in the scientific community
• Junk Science (no peer review)
– False information presented in a scientific way that is
meant to be misleading and is not accepted by the
scientific community
Types of Matter
– ATOM - The smallest particle of an element that retains
the chemical properties of that element.
– ELEMENT - Matter that is composed of only one type
of atom.
– MOLECULE - A definite group of atoms that are
chemically bonded, i.e. tightly connected by attractive
forces.
– COMPOUND - Matter that is composed of 2 or more
elements combined in definite proportions.
Law of Conservation of Mass:
• Total mass remains constant throughout a
chemical reaction
• ex. 2Hg + O2 ---> 2HgO, where the mass
of the 2Hg = 2.53g and the mass of the
2HgO = 2.73g, the mass of the O2 has to
equal 0.20g.
PROTONS
• PROTONS – are defined as:
– positively charged subatomic particles with a
charge of +1.602x10-19 coulombs
– found inside the nucleus
– composed of 2 up quarks and 1down quark
– mass = 1.672622x10-24 g or 1.007276 AMU
* The elements atomic number ( Z#) = # protons
NEUTRON
• NEUTRONS – are defined as
–
–
–
–
electrically neutral subatomic particle
found inside the nucleus
composed of 2 down quarks and 1 up quark
mass = 1.674927x10-24 g or 1.008665 AMU.
NUCLEUS
• NUCLEUS – is defined as:
–
–
–
–
–
–
core of the atom
centrally located
positively charged
contains most of the atom's mass
very dense
small relative to the overall size of the atom
ELECTRONS
• ELECTRONS – are defined as:
– negatively charged subatomic particle with a charge
of -1.602x10-19 coulombs
– leptons
– found outside of the core of the atom
– mass = 9.1x10-28 g or 0.00055 AMU
– travel in orbitals around the nucleus
– mostly empty space
– occupies most of the size of the atom
ATOMS
• ATOMS – are defined as:
– smallest particle of an element that retains the
chemical properties of that element
– composed of the nucleus (core) surrounded by
electrons
ISOTOPES
• ISOTOPES – are defined as:
– Atoms of the same atomic number but different mass
B-10 = Boron has 10 mass units, 5 protons & 5 neutrons
B-11 = Boron also can have 11 mass units, 5p & 6n
C-12 = Carbon has 12 mass units, 6 protons & 6 neutrons
C-14 = Carbon has 14 mass units, 6 protons & 8 neutrons
U-234 = Uranium has 234 mass units, ?
U-235 = ?
U-238 = ?
Periodic Table of Elements
• Periodic Table is a reference table of the 117
elements that are currently identified, 92 are
naturally occurring, which are displayed in periods
(rows) and families (columns) so that similarities
and differences can easily be recognized for use in
the sciences
• See handout of Periodic Table
• Locate the interactive CD from my webpage and
explore it
Ions and Ionic Compounds
• Ions are atoms or groups of atoms that have
lost or gained electrons resulting in an
overall positive or negative charges.
• Ionic compounds are compounds formed by
the combination of (+) and (-) ions.
(+) ions are called cations
(-) ions are called anions
Common Polyatomic Ions
•
•
•
•
•
•
•
•
carbonate ion
sulfate ion
sulfite ion
hydroxide
phosphate
permanganate
chromate
dichromate
CO3-2
SO4-2
SO3-2
OHPO4-3
MnO4CrO4-2
Cr2O7-2
•
•
•
•
•
•
•
•
ammonium
oxalate
bicarbonate
cyanide ion
acetate
peroxide
thiosulfate
bisulfite
NH4+
C2O4-2
HCO3-2
CNC2H3O2O2-2
S2O3-2
HSO3-
Basic Chemicals in ENV 101
H2O – water
O2 – oxygen
O3 – ozone
N2 – nitrogen
N2O – nitrous oxide
NO – nitric oxide
H2S – hydrogen sulfide
C6H12O6 – glucose
CO – carbon monoxide
CO2 – carbon dioxide
NO2 – nitrogen dioxide
SO2 – sulfur dioxide
SO3 – sulfur trioxide
NH3 – ammonia
H2SO4 – sulfuric acid
HNO3 – nitric acid
CH4 – methane
HCl – hydrochloric acid
Organic Compounds
• Hydrocarbons – compounds composed of
hydrogen and carbon ex. CH4, methane which is
the major component in natural gas
• Chlorinated hydrocarbons – hydrocarbons that
have chlorines attached, ex. C14H9Cl5 , an
insecticide which has been named DDT
• Simple carbohydrates – simple sugars made up of
carbon, hydrogen and oxygen, ex. C6H12O6,
glucose which most plants and animals metabolize
in their cells to produce energy
Complex Organic Molecules
• Polymers – consisting of a number of basic units
(monomers) linked together
– Complex carbohydrates – made up of monomers of
simple sugars linked together
– Proteins – formed by monomers of amino acids linked
together
– Nucleic acids – linked sequences of monomers called
nucleotides
• Genes consist of nucleotides in DNA which carries code
needed to make proteins
• Chromosomes are a combination of genes and proteins that
make up DNA
Physical States of Matter:
• Solid - Relatively incompressible, has a
fixed shape and fixed volume.
• Liquid - Has a fixed volume and takes the
shape of its container, fluid, and
incompressible.
• Gas (Vapor)- Takes the shape of its
container, fluid, and is compressible.
Physical vs. Chemical Change:
• Physical Change = Change that takes place
in the form or phase of matter, but not in
its chemical identity.
• Chemical Change = Change that involves
the combination, recombination, or
separation of atoms with each other.
The Balanced Equation
2Al(s) + 3Br2(l)  Al2Br6(s)
• The chemicals on the left are the reactants
and the right are the products.
• The coefficient in front of the chemical
denotes the stoichiometric relationship.
Numerical Subscripts
2Al(s) + 3Br2(l)  Al2Br6(s)
• The numerical subscript represents the
number of atoms present in the molecule
– ex. Br2 means that an atom of Br is
bonded to another atom of Br
– Therefore:
Br-Br = Br2
Phases of Matter
2Al(s) + 3Br2(l)  Al2Br6(s)
The subscript letters in parenthesis denote the
phase of matter that the chemical is in.
Phase of Matter
Symbol
Solid
(s)
Liquid
(l)
Gas
(g)
Aqueous
(aq)
Energy
• Kinetic Energy – energy of motion
• Potential energy – energy at rest
• High-quality Energy – high output and
ability to do work
• Low-quality Energy – low output
Thermodynamics
• Thermodynamics is the study of heat energy
– Endothermic process is positive (+) and
involves the absorption of heat
– Exothermic process is negative (-) and involves
the release of heat
• Heat transfer
– Conduction
– Convection
– Radiant
Nuclear Change
• Nuclear reactions case changes within the nucleus
of an atom
• Natural Radioactive Decay – occurs when an
unstable isotope spontaneously releases particles
from the atom Nuclear Fission – occur when
isotopes are split apart by bombardment with
neutrons (see Figures 2-6 & 2-7 on pg 28)
• Nuclear Fusion – occurs when 2 isotopes join
together to form a heavier isotope
What Is Light?
• Light is bundles of energy called “PHOTONS” that
travel in waves through an electrical and magnetic
field. (See Fig 2-8 on pg 29)
• Photons have no mass.
• Photons are released when electrons are deexcited from an excited state.
What Are Waves?
What’s a Wavelength?
Systems
def. System – a set of components that
function and interact together as a unit,
which allows them to be studied
Inputs >
Flows > Outputs
+ Feedback – change in the same direction
- Feedback – change in the opposite direction
Types of Pollutants
Three factors are used to determine how
severe a pollutant is:
1. Chemical nature – the many chemical
properties that a substance or compound has
2. Concentration – usually measured in ppm =
1part pollutant/1 million parts matter or parts
per billion (ppb)
3. Persistence – measure of how long a pollutant
will remain in a system
Types of Pollutants (cont.)
• Degradable or non-persistent – easily broken
down to safer non-toxic matter
• Biodegradable – complex chemicals that are
broken down through biological action (specific
bacteria)
• Slowly degradable or persistent – take decades or
longer to degrade
• Non-degradable – can not be broken down
therefore they remain in the system and can
contaminate a whole host of organisms
Synergy
• Synergistic effect – build up of effects that
create a heightened or accelerated effect
Ex. Exposure to a drug and drinking alcohol can
create a heightened effect that may damage your
liver, nervous system, heart etc. for more than the
individual effects of each chemical.
Ex. Different perfumes can combine and form noxious
fumes in a closed room.
Unsustainable High-Throughput
vs. Matter-Recycling Economy
• High-throughput economy – economic
growth by a one-way flow of matter and
energy resources that produce large
amounts of waste
• Matter-recycling economy – economic
growth slowing down depletion of matter
resources in order to reduce excessive
pollution
Sustainable Low - Throughput
• Living more sustainably by reducing the
throughput of matter and energy
– Not wasting matter & energy
– Recycling & reusing matter resources
– Stabilizing our population