matter and energy chapter two. concepts matter consists of elements and compounds, which in turn are...
TRANSCRIPT
Concepts
• Matter consists of elements and compounds, which in turn are made up of atoms, ions, or molecules
• Whenever matter undergoes a physical or chemical change, no atoms are created or destroyed (the law of conservation of matter)
What is matter?
• Three physical states:– Solid– Liquid– Gas
• Two chemical forms of matter:– Elements– Compounds
Other facts about matter:
• The smallest unit of matter is ___?
• What is an ion?• What is a molecule
and how are they held together?
• What are subscripts and what do they represent?
• The three physical states of matter on earth are____.
What is an element?
• A fundamental type of matter that has a unique set of properties and cannot be broken down into simpler substances by chemical means
• Periodic table: elements arranged based on their chemical behavior
Some important elements
• Composition of the earth’s crust
• Inorganic compounds• All compounds that do
not contain carbon• Crust - outermost
layer of earth - mainly inorganic minerals and rocks
Atomic Theory
• All elements are made of atoms
• Most widely accepted scientific theory in chemistry
The Atom
• Major parts of the atom are:– Protons
– Neutrons
– Electrons
• The protons and neutrons form the ___
• Electrons are located in ____
• What is the atomic number?
• What is the mass number?
• What are isotopes?• How do you identify
isotopes in the symbol?
Molecule
• A second building block of matter
• Combination of two or more atoms of the same or different elements held together by chemical bonds
• Basic building blocks of any compound
WHAT ARE IONS?
• IF AN ATOM HAS 11 PROTONS AND 10 ELECTRONS IT IS A ______ION.
• IF IT HAS 17 PROTONS AND 18 ELECTRONS IT IS A ___ ION.
• HOW ARE THE CHARGES ON AN ION SHOWN AFTER THE SYMBOL?
Holding atoms together
• What does a chemical formula tell you?
• What are the characteristics of ionic bonds?
• What is an example of an ionic bond?
• What are covalent bonds?
• What is an example of a covalent bond?
• What are hydrogen bonds?
• What is an example of a hydrogen bond compound?
What are organic compounds?
• What element do all organic compounds contain? What other elements can be also combined?
• Organic compounds can be natural or synthetic.
• Most organic compounds are covalent bonds.
Types of organic compounds:
• Hydrocarbons made up of ___
• Chlorinated hydrocarbons– An example would be:
• Chlorofluorocarbons -– An example would be:
• Simple carbohydrates
• Monomers• Polymers• Complex
carbohydrates• Proteins• Nucleic acids
MORE ON PROTEINS:
• ALPHA-AMINO ACIDS - 20 DIFFERENT MONOMERS - # & SEQUENCE SPECIFIED BY GENETIC CODE IN DNA MOLECULES IN CELLS
• NUCLEIC ACIDS - DNA & RNA - MADE BY LINKING MONOMERS CALLED NUCLEOTIDES TOGETHER
• GENES - SEUQENCES OF NUCLEOTIDES - CARRIES A CODE WHICH CONTAINS TRAITS PASSED FROM PARENTS TO OFFSPRING
• GENOME - ALL OF THE GENETIC INFORMATION FOR AN ORGANISM.
• What are GENE MUTATIONS?
• What are CHROMOSOMES?
Matter quality
• A measure of how useful a matter resource is - based on availability and concentration
• High quality matter -organized, concentrated and usually found near earth’s surface
• Low quality - disorganized, dilute,often deep underground or dispersed in the ocean or atmosphere - have little potential use as a matter resource.
WHAT IS ENERGY?
• What is ENERGY ?
• What is WORK?
• What is a FORCE?
• Forms of energy - light, heat, electricity, chemical energy, mechanical energy, and nuclear energy
Types of energy
• What is Kinetic energy? • What does it depend
on?• Examples: wind,
flowing water, electricity, electromagnetic radiation, heat, temperature
• What is Potential energy?
• What does it depend on?
• Potential energy changes into kinetic energy etc.
Kinetic Energy
• Heat (thermal energy)– Total kinetic energy of all moving atoms, ions,
or molecules in an object, a body of water, or the atmosphere
– Faster moving particles = warmer
Temperature vs Heat
• What is temperature?– The average speed of the
motion of the molecules in a given sample of matter
• What is heat?– The total kinetic energy of
all the moving molecules within a given substance
Kinetic Energy
• Electromagnetic radiation– Energy travels in the form of a wave as a result
of changes in electrical and magnetic fields– Each form of electromagnetic radiation has a
• Wavelength
• Energy content
• Short wavelengths = more energy (gamma rays)
Electromagnetic spectrum
• Ionizing radiation - harmful forms of electromagnetic radiation
• Non-ionizing radiation - does not contain enough energy to form ions
• Ionizing Radiation – from natural or background sources– Can come from space, soil, food, etc.– Has energy to knock electrons from atoms
• Can disrupt living cells, interfere with body processes and cause cancer.
– Nonionizing radiation doesn not contain enough energy to form ions.
Energy quality
• An energy source’s ability to do useful work
• High-quality - organized or concentrated - can perform useful work– Electricity, coal, gasoline, sunlight,uranium
• Low - quality - disorganized or dispersed- can perform little useful work– Heat in water, air, etc.
Changes in matter
• What is a Physical change?
• What are some examples of physical changes?
• All changes involve energy - taken in or released
• What is a Chemical change ?
• What is an example?• What is a CHEMICAL
Equation?• Reactants --> products
Law of Conservation of Matter
• All the matter on earth is here and cannot be “thrown away” - there is no “away”
• Earth is a closed system
• Matter cannot be created nor destroyed
• Matter is not consumed
Law of Conservation of matter and energy
• Applies to nuclear changes because a certain amount of mass (matter) is changed into energy.
• The TOTAL amount of matter and energy involved remains the same
Nuclear Changes
• Natural radioactivity- when nuclei of certain isotopes spontaneously break down into one or more different isotopes
• Three types:– Natural radioactive decay
– Nuclear fission
– Nuclear fusion
Natural radioactive decay
Unstable isotopes - radioisotopes - spontaneously break down and emit:
• Alpha particles - positively charged helium nuclei
• Beta particles - high speed electrons
• Gamma rays - high speed ionizing electromagnetic radiation
Half-life
• Rate of decay
• Time needed for one half of the nuclei in a radioisotope to decay and emit their radiation
• Eventually forms a new element
• Is not affected by temp. pressure, chemical changes, etc.
• Rule is store for 10 half-lives for safety
Nuclear fission
• Nuclei of atoms with large mass numbers are split into lighter nuclei
• Neutrons used to split• Releases more
neutrons and energy• Critical mass - needed
to start reaction
More on fission
• Atomic bombs - uncontrolled nuclear fission
• Damage cells• Used in nuclear power
plants
Nuclear fusion
• Two isotopes of light elements are combined under great heat and pressure to form a heavier nucleus
• Harder to initiate• Thermonuclear
weapons
Net Energy• Only Energy that really counts
• Energy Quality – we want to use resources that produce the most net energy and expend very little energy
• P 375
• Net energy yield: the usable amount of high-quality energy available from an energy resource
What is energy efficiency?
• A measure of how much useful work is accomplished by a particular input of energy into a system
• Always measured as a percent (%)
• Affects life because you get and use high quality matter and energy , use it and add low quality heat and waste back into the environment.
Energy Inefficiency• Costs $570,000 per minute (US)• Due to:
– Data Centers (electronic clouds) – use only 10% of the electric energy they pull from the grid – other 90% ends up as low-quality heat that flows into the environment
– Internal combustion engine – motor vehicles (wastes 80% of the energy in the fuel)
– Nuclear power plants – produce electricity but waste about 75% of the energy in the nuclear fuel
– Coal-fired power plants – wastes about 65% of the energy that is released by burning coal
Nuclear Power Plants
• Thermal power station in which the heat source is a nuclear reactor
• Heat is used the generate steam, which drives a steam turbine connected to an electric generator
• This produces electricity
• 435 nuclear power plants
LWRs• Core
– fuel rods – packed with pellets = 1 ton of coal • Provide fuel for nuclear reactors
– control rods - absorb neutrons and slow reaction down
– water - keeps core cool(coolant), slows down the neutrons so that they are at the right speed to trigger the next reaction (moderator) and produces steam to make electricity
• high pressure steam from reactor is used to heat water which then produces steam used to run a turbine
Pressurized Water Reactor
• Constitutes the large majority of all Western nuclear power plants
• Light water reactor• The primary coolant (water) is pumped under high
pressure to the reactor core where it is heated by the energy generated by the fission of atoms
• The water then flows to a steam generator where it transfers its thermal energy to a secondary system where steam is generated and flows to turbines
Pressurized Water Reactor
• Animation
• http://commons.wikimedia.org/w/index.php?title=File%3APWR_nuclear_power_plant_animation.ogv
Boiling water reactors
• Light water nuclear reactor used to generate electrical power
• Main difference from PWR: the reactor core in the PWR does not boil the water
• Developed by Idaho National Laboratory and General Electric in the mid-1950s
Turbine
• Greek: “Turbulence”
• A rotary mechanical device that extracts energy from a fluid flow and converts it into useful work
• Purpose of steam turbine: convert the heat contained in steam into mechanical energy
First law of thermodynamics
• In all physical and chemical changes, energy is neither created nor destroyed but it may be converted from one form to another
• Energy input always equals energy output
• You can’t get something for nothing - cannot get more energy out of a system than is put in!!!
Second law of thermodynamics
• When energy is changed from one form to another, some useful energy is always degraded to lower quality less useful energy usually heat lost to the environment
• We ALWAYS end up with less useful energy than we started with.
• An incandescent light bulb - 5 % light, 95% heat