Transcript Chapter 2

Chapter 2
Science, Systems,
Matter, and Energy
TYPES AND STRUCTURE OF
MATTER
 Elements

and Compounds
Matter exists in chemical forms as elements and
compounds.
• Elements (represented on the periodic table) are the
building blocks of matter.
• Compounds: two or more different elements held
together in fixed proportions by chemical bonds.
Basic Chemistry
 Matter,



Mass, and Weight
Matter: Anything that occupies space and
has mass
Mass: The amount of matter in an object
Weight: The gravitational force acting on
an object of a given mass
 Elements


and Atoms
Elements: The simplest type of matter with
unique chemical properties
Atoms: Smallest particle of an element that
has chemical characteristics of that element
Atoms
Figure 2-4
Atomic Structure

Atoms: composed of
subatomic particles




Neutrons: no electrical
charge
Protons: positive charge
Electrons: negative
charge
Nucleus


Formed by protons and
neutrons
Most of volume of atom
occupied by electrons
Atomic Number and Mass Number

Atomic Number: Equal to number of protons in
each atom which equals the number of electrons
 Mass Number: Number of protons plus number of
neutrons
Isotopes and Atomic Mass

Isotopes: Two or more forms of same element
with same number of protons and electrons but
different neutron number



3 types of hydrogen
Denoted by using symbol of element preceded by mass
number as 1H, 2H, 3H
Atomic Mass: Average mass of naturally
occurring isotopes
Molecules and Compounds
 Molecules:
Two or more atoms form a
covalent bond

Example: Water
 Compounds:
A substance composed of
two or more different types if atoms
chemically combined

Example: Hydrogen Molecule
 Molecular
Mass: Determined by adding
up atomic masses of its atoms or ions

Example: NaCl (22.99 + 35.45)
Covalent Bonding

Atoms share one or
more pairs of electrons



Single covalent:
Electron pair between 2
atoms
Double covalent: Two
atoms share 4 electrons
Nonpolar covalent:
Electrons shared
equally
 Polar covalent:
Electrons not shared
equally
Electrons and Chemical Bonding

Ion: When an atom loses or gains electrons
and become charged



Cation: Positively charged ion
Anion: Negatively charged ion
Ionic Bonding

Cations and anions are attracted to each other
Ions
 An
ion is an atom or group of atoms with one
or more net positive or negative electrical
charges.
 The number of positive or negative charges
on an ion is shown as a superscript after the
symbol for an atom or group of atoms


Hydrogen ions (H+), Hydroxide ions (OH-)
Sodium ions (Na+), Chloride ions (Cl-)
Compounds and Chemical Formulas
 Chemical
formulas are shorthand ways to
show the atoms and ions in a chemical
compound.


Combining Hydrogen ions (H+) and Hydroxide
ions (OH-) makes the compound H2O
(dihydrogen oxide, a.k.a. water).
Combining Sodium ions (Na+) and Chloride ions
(Cl-) makes the compound NaCl (sodium chloride
a.k.a. salt).
Synthesis and Decomposition
Reactions


Synthesis Reactions
 Two or more
reactants chemically
combine to form a
larger product
Decomposition
Reactions
 Reverse of synthesis
reactions
Acids and Bases; Salts and Buffers
 Acid:
A proton donor or any substance
that releases hydrogen ions
 Bases: A proton acceptor or any
substance that binds to or accepts
hydrogen ions
 Buffers: Able to maintain the pH
The pH Scale

Refers to the
Hydrogen ion
concentration in a
solution



Neutral: pH of 7 or
equal hydrogen and
hydroxide ions
Acidic: a greater
concentration of
hydrogen ions
Alkaline or basic: a
greater concentration
of hydroxide ions
 The
pH (potential of Hydrogen) is the
concentration of hydrogen ions in one liter of
solution.
Figure 2-5
Chemistry
 Inorganic
Chemistry: Generally substances
that do not contain carbon


Water
Oxygen
 Organic
Chemistry: Study of carboncontaining substances
Organic Compounds: Carbon Rules
 Organic
compounds contain carbon atoms
combined with one another and with various
other atoms such as H+, N+, or Cl-.
 Contain at least two carbon atoms combined
with each other and with atoms.


Methane (CH4) is the only exception.
All other compounds are inorganic.
Organic Chemistry
 Carbohydrates

Composed of carbon, hydrogen, oxygen
 Lipids

Composed mostly of carbon, hydrogen, oxygen
 Proteins

Composed of carbon, hydrogen, oxygen,nitrogen
 Nucleic

Acids: DNA and RNA
Composed of carbon, hydrogen, oxygen, nitrogen,
phosphorus
 Adenosine

Triphosphate (ATP)
Composed of adenosine and three phosphate groups
Carbohydrates
 Monosaccharides

or building blocks
Simple sugars: glucose, fructose, galactose
 Disaccharides

Two simple sugars bound together by
dehydration: sucrose, lactose, maltose
 Polysaccharides

Long chains of many monosaccharides:
glycogen in animals; starch and cellulose in
plants
Lipids

Lipids: Can be dissolved in nonpolar organic
solvents as alcohol or acetone but relatively
insoluble in water





Fats, Oils and Waxes.
Triglycerides: composed of glycerol and fatty
acids
Phospholipids: Important structural component
of cell membranes
Steroids: Cholesterol, bile salts, estrogen,
testosterone
Fat-soluble Vitamins
Proteins
 Amino
acids: The building blocks of
protein
 Peptide bonds: Covalent bonds formed
between amino acids during protein
synthesis
 Structure

Primary, secondary, tertiary, quartenary
 Enzymes:



Protein catalysts
Lock-and-key model
Active site
Coenzymes
Protein Structure and Enzyme Action
Nucleic Acids: DNA and RNA
 DNA:


Deoxyribonucleic acid
Genetic material of cells copied from one
generation to next
Composed of 2 strands of nucleotides
• Each nucleotide contains one of the organic
bases of adenine or guanine which are purines
and thymine or cystosine which are pyrimidines
 RNA:

Ribonucleic acid
Similar to a single strand of DNA
• Four different nucleotides make up organic
bases except thymine is replaced with uracil
(pyrimidine)
DNA Structure
Water
 Inorganic
 Stabilizes
body temperature
 Protection
 Necessary
for many chemical reactions
of life
 Mixing Medium

Mixture: Substance physically but not
chemically combined
• Solution: Liquid, gas, or solid uniformly
distributed


Solvent: What dissolves the solute
Solute: What is to be dissolved
Acids and Bases; Salts and Buffers
 Acid:
A proton donor or any substance
that releases hydrogen ions
 Bases: A proton acceptor or any
substance that binds to or accepts
hydrogen ions
 Salts: A cation consisting of other than
a hydrogen ion and other than an anion
or hydroxide ion
 Buffers: A solution of a conjugate acidbase pair in which acid and base
The pH Scale

Refers to the
Hydrogen ion
concentration in a
solution



Neutral: pH of 7 or
equal hydrogen and
hydroxide ions
Acidic: a greater
concentration of
hydrogen ions
Alkaline or basic: a
greater concentration
of hydroxide ions
Energy
 Energy:





The capacity to do work
Potential Energy: Stored energy
Kinetic Energy: Does work and moves
matter
Mechanical Energy: Energy resulting from
the position or movement of objects
Chemical Energy: Form of potential energy
in the chemical bonds of a substance
Heat Energy: Energy that flows between
objects of different temperatures
Energy and Chemical Reactions
Speed of Chemical Reactions

Activation Energy: Minimum energy reactants
must have to start a chemical reaction


Catalysts: Substances that increase the rate of
chemical reactions without being permanently
changed or depleted
Enzymes: Increase the rate of chemical reactions
by lowering the activation energy necessary for
reaction to begin
Activation Energy and Enzymes
Cells: The Fundamental Units of Life
 Cells
are the basic
structural and
functional units of all
forms of life.


Prokaryotic cells
(bacteria) lack a distinct
nucleus.
Eukaryotic cells (plants
and animals) have a
distinct nucleus.
Figure 2-6
Animation: Prokaryotic and
Eukaryotic Cells
PLAY
ANIMATION
A human body contains trillions
of cells, each with an identical
set of genes.
There is a nucleus inside each
human cell (except red blood cells).
Each cell nucleus has an identical
set of chromosomes, which are
found in pairs.
A specific pair of chromosomes
contains one chromosome from
each parent.
Each chromosome contains a long
DNA molecule in the form of a coiled
double helix.
Genes are segments of DNA on
chromosomes that contain instructions
to make proteins—the building blocks
of life.
The genes in each cell are coded
by sequences of nucleotides in
their DNA molecules.
Stepped Art
Fig. 2-7, p. 38
 All
Living Organisms are
made up of Macromolecules:




Complex Carbohydrates
Proteins
Nucleic Acids
Lipids
Figure 2-7
States of Matter
 The
atoms, ions, and molecules that make up
matter are found in three physical states:

solid, liquid, gaseous.
A
fourth state, plasma, is a high energy
mixture of positively charged ions and
negatively charged electrons.


The sun and stars consist mostly of plasma.
Scientists have made artificial plasma (used in
TV screens, gas discharge lasers, florescent
light).
Matter Quality
 Matter
can be classified
as having high or low
quality depending on
how useful it is to us as
a resource.


High quality matter is
concentrated and easily
extracted.
low quality matter is more
widely dispersed and
more difficult to extract.
Figure 2-8
CHANGES IN MATTER
 Matter
can change from one physical form to
another or change its chemical composition.

When a physical or chemical change occurs, no
atoms are created or destroyed.
• Law of conservation of matter.


Physical change maintains original chemical
composition.
Chemical change involves a chemical reaction
which changes the arrangement of the elements
or compounds involved.
• Chemical equations are used to represent the
reaction.
Chemical Change

Energy is given off during the reaction as a product.
Types of Pollutants
 Factors
that determine the severity of a
pollutant’s effects: chemical nature,
concentration, and persistence.
 Pollutants are classified based on their
persistence:




Degradable pollutants
Biodegradable pollutants
Slowly degradable pollutants
Nondegradable pollutants
Nuclear Changes in Atoms
 Natural
radioactive decay: unstable isotopes
spontaneously emit fast moving chunks of
matter (alpha or beta particles), high-energy
radiation (gamma rays), or both at a fixed
rate.


Radiation is commonly used in energy production
and medical applications.
The rate of decay is expressed as a half-life (the
time needed for one-half of the nuclei to decay to
form a different isotope).
Animation: Positron-Emission
Tomography
PLAY
ANIMATION
Animation: Half-Life
PLAY
ANIMATION
Nuclear Changes: Fission
 Nuclear
fission:
nuclei of certain
isotopes with large
mass numbers are
split apart into
lighter nuclei when
struck by neutrons.
Figure 2-9
Uranium-235
Uranium-235
Uranium-235
Energy
Fission
fragment
Uranium-235
n
n
Neutron
n
n
Energy
n
Uranium-235
Uranium-235
Energy
n
Fission
fragment
Uranium-235
Energy
Uranium-235
Uranium-235
Uranium-235
Stepped Art
Fig. 2-6, p. 28
Nuclear Changes: Fusion
 Nuclear
fusion: two isotopes of light elements
are forced together at extremely high
temperatures until they fuse to form a heavier
nucleus.
Figure 2-10
Video: Nuclear Energy
PLAY
VIDEO

From ABC News, Environmental Science in the Headlines, 2005 DVD.
ENERGY
 Energy
is the ability to do work and transfer
heat.

Kinetic energy – energy in motion
• heat, electromagnetic radiation

Potential energy – stored for possible use
• batteries, glucose molecules
Electromagnetic Spectrum
 Many
different forms of electromagnetic
radiation exist, each having a different
wavelength and energy content.
Figure 2-11
Electromagnetic Spectrum
 Organisms
vary
in their ability to
sense different
parts of the
spectrum.
Figure 2-12
Animation: Visible Light
PLAY
ANIMATION
Source of Energy
Electricity
Very high temperature heat
(greater than 2,500°C)
Nuclear fission (uranium)
Nuclear fusion (deuterium)
Concentrated sunlight
High-velocity wind
Relative
Energy Tasks
Energy Quality
(usefulness)
Very high-temperature heat
(greater than 2,500°C) for
industrial processes and
producing electricity to run
electrical devices (lights,
motors)
High-temperature heat
(1,000–2,500°C)
Hydrogen gas
Natural gas
Gasoline
Coal
Food
Mechanical motion to move
vehicles and other things)
High-temperature heat
(1,000–2,500°C) for
industrial processes and
producing electricity
Normal sunlight
Moderate-velocity wind
High-velocity water flow
Concentrated geothermal energy
Moderate-temperature heat
(100–1,000°C)
Wood and crop wastes
Moderate-temperature heat
(100–1,000°C) for
industrial processes, cooking,
producing
steam, electricity, and
hot water
Dispersed geothermal energy
Low-temperature heat
(100°C or lower)
Low-temperature heat
(100°C or less) for
space heating
Fig. 2-13, p. 44
ENERGY LAWS: TWO RULES WE
CANNOT BREAK
 The
first law of thermodynamics: we cannot
create or destroy energy.

We can change energy from one form to another.
 The
second law of thermodynamics: energy
quality always decreases.


When energy changes from one form to another,
it is always degraded to a more dispersed form.
Energy efficiency is a measure of how much
useful work is accomplished before it changes to
its next form.
Chemical
energy
(photosynthesis)
Solar
energy
Waste
Heat
Mechanical
energy
(moving,
thinking,
living)
Chemical
energy
(food)
Waste
Heat
Waste
Heat
Waste
Heat
Fig. 2-14, p. 45
SUSTAINABILITY AND MATTER
AND ENERGY LAWS
 Unsustainable
High-Throughput Economies:
Working in Straight Lines

Converts resources to goods in a manner that
promotes waste and pollution.
Figure 2-15
Sustainable Low-Throughput
Economies: Learning from Nature
 Matter-Recycling-and-Reuse
Economies:
Working in Circles


Mimics nature by recycling and reusing, thus
reducing pollutants and waste.
It is not sustainable for growing populations.
Inputs
(from environment)
Energy
Matter
System
Throughputs
Outputs
(into environment)
Energy
conservation
Waste
and
pollution
Low-quality
Energy
(heat)
Sustainable
low-waste
economy
Pollution
control
Matter
Feedback
Waste
and
pollution
Recycle
and
reuse
Energy Feedback
Fig. 2-16, p. 47
Animation: Economic Types
PLAY
ANIMATION