Science, System, Matter, Energy

Shohail ChoudhuryShohail Choudhury

Introduction toIntroduction to

ENVIRONMENTAL SCIENCEENVIRONMENTAL SCIENCEIntroduction toIntroduction to

ENVIRONMENTAL SCIENCEENVIRONMENTAL SCIENCE

Living in the EnvironmentLiving in the Environment

1414thth Edition Edition

Chapter 3Chapter 3

Science, Systems, Science, Systems, Matter and EnergyMatter and Energy

33

The Nature of ScienceThe Nature of ScienceThe Nature of ScienceThe Nature of Science

Ask a question

Do experimentsand collect data

Formulatehypothesis

to explain data

Do moreExperiments totest hypothesis

Revise hypothesisif necessary

Well-tested andaccepted

hypothesesbecome

scientific theories

Interpret data

Well-tested andaccepted patternsIn data becomescientific laws

Ask a question

Do experimentsand collect data

Formulatehypothesis

to explain data

Do moreExperiments totest hypothesis

Revise hypothesisif necessary

Well-tested andaccepted

hypothesesbecome

scientific theories

Interpret data

Well-tested andaccepted patternsIn data becomescientific laws

What is Science What is Science and What Do Scientists do?and What Do Scientists do?

Science is an attempt to discover order Science is an attempt to discover order in the natural world and use that to in the natural world and use that to predict.predict.

Scientists collect data, form Scientists collect data, form hypotheses, and develop theories, hypotheses, and develop theories, models and laws about how nature models and laws about how nature works.works.

Fig: What scientists do?

Models and Behaviour of SystemsModels and Behaviour of SystemsModels and Behaviour of SystemsModels and Behaviour of Systems

Scientists use models or simulations to find out how systems Scientists use models or simulations to find out how systems work and to evaluate ideas or hypothesis. work and to evaluate ideas or hypothesis.

A system is a set of components that function A system is a set of components that function in some regular manner.in some regular manner.

Most systems haveMost systems have

1.1. Inputs (from the environment)Inputs (from the environment)

2.2. Flows or throughputsFlows or throughputs

3.3. Outputs (to environment) Outputs (to environment)

MatterMatterMatterMatter

What types of matter do we find in nature?What types of matter do we find in nature?

Matter is anything that has mass and takes up space. Matter is anything that has mass and takes up space.

Matter has two forms:Matter has two forms:

1. Elements: building blocks of matter.1. Elements: building blocks of matter.

2. Compounds: 2 or more elements held together by 2. Compounds: 2 or more elements held together by chemical bonds.chemical bonds.

Chemists use symbols: e.g. Carbon (C), Oxygen (O), Chemists use symbols: e.g. Carbon (C), Oxygen (O), Calcium (Ca).Calcium (Ca).

Building Blocks of MatterBuilding Blocks of MatterBuilding Blocks of MatterBuilding Blocks of Matter

Atom: The smallest unit of matter.Atom: The smallest unit of matter.

Ion: An electrically charged atom/atomsIon: An electrically charged atom/atoms

Molecule: A combination of two or more atoms of Molecule: A combination of two or more atoms of the same or different elements.the same or different elements.

In nature we find molecules. For example nitrogen (NIn nature we find molecules. For example nitrogen (N22) )

and oxygen (Oand oxygen (O22) are found in air. ) are found in air.

Here 2 is number of Atoms. Here 2 is number of Atoms.

Ex: OEx: O33 is Ozone. is Ozone.

Inside AtomInside AtomInside AtomInside Atom

1. Protons (positively charged)1. Protons (positively charged)

2. Neutrons (uncharged)2. Neutrons (uncharged)

3. Electron (negatively charged)3. Electron (negatively charged)

Centre of the atom is Nucleus.Centre of the atom is Nucleus.

Equal number of protons and Equal number of protons and electrons. So no net electrical charge.electrons. So no net electrical charge.

Each element has a specific atomic number.Each element has a specific atomic number. Atomic number is equal to number of protons in the nucleus.Atomic number is equal to number of protons in the nucleus.

H=1, C=6, U=92H=1, C=6, U=92

An atom is made up of a cloud of electrons that surrounds a nucleus An atom is made up of a cloud of electrons that surrounds a nucleus containing protons and (in most cases) neutrons.containing protons and (in most cases) neutrons.

Most of the mass of an atom is concentrated in the nucleus. So Most of the mass of an atom is concentrated in the nucleus. So Atomic Mass= P+N in its nucleus. Atomic Mass= P+N in its nucleus.

Examples of IsotopesExamples of IsotopesExamples of IsotopesExamples of Isotopes

Different isotopes of an Different isotopes of an element have different element have different mass numbers.mass numbers.

Isotopes: Elements Isotopes: Elements with different Neutron with different Neutron numbers.numbers.

Atomic Mass= P+NAtomic Mass= P+N

Ions and Ions and PPHHIons and Ions and PPHH

Atoms of some elements can lose or gain electrons to form ions.Atoms of some elements can lose or gain electrons to form ions.

(See CD: (See CD:

Metals: Electron giversMetals: Electron giversNon-metals: Electron receiversNon-metals: Electron receivers

HH+ + ions in a solution are a measure of how acidic or basic it is. ions in a solution are a measure of how acidic or basic it is.

The pH of a solution is a measure of its concentration of The pH of a solution is a measure of its concentration of hydrogen ions (Hhydrogen ions (H++). ).

Neutral pH is 7; acid solutions are below 7; Neutral pH is 7; acid solutions are below 7; and basic solutions are above 7.and basic solutions are above 7.

Chemical formulas of a compoundChemical formulas of a compound

Chemical formulas are a type of shorthand to show the type Chemical formulas are a type of shorthand to show the type and number of atoms/ions in a compound.and number of atoms/ions in a compound.

1.1. Each element in the compound is represented by a Each element in the compound is represented by a symbol: H = hydrogen, N = nitrogen.symbol: H = hydrogen, N = nitrogen.

2.2. Subscripts show the number of atoms/ions in the Subscripts show the number of atoms/ions in the compound.compound.

3.3. Ionic compounds are made up of oppositely charged Ionic compounds are made up of oppositely charged ions, (Na+ and Cl-). ions, (Na+ and Cl-). (See CD)

4.4. Compounds made of uncharged atoms are called Compounds made of uncharged atoms are called covalent (or molecular) compounds (CHcovalent (or molecular) compounds (CH44) (H) (H22O).O).

Organic compounds contain carbon atoms Organic compounds contain carbon atoms combined with one another and with combined with one another and with various other atoms. Only methane (CHvarious other atoms. Only methane (CH44) )

has one carbon atom.has one carbon atom.

1.1. Hydrocarbons: compounds of carbon and Hydrocarbons: compounds of carbon and hydrogen atoms. hydrogen atoms. Methane (CH4)Methane (CH4)

2.2. Chlorinated hydrocarbons: compounds of Chlorinated hydrocarbons: compounds of carbon, hydrogen, and chlorine atoms.carbon, hydrogen, and chlorine atoms.DDT (CDDT (C1414HH99ClCl55))

3. 3. Simple carbohydrates: specific types of Simple carbohydrates: specific types of compounds of carbon, hydrogen, and compounds of carbon, hydrogen, and oxygen atoms. oxygen atoms. Glucose (CGlucose (C66HH1212OO66))

CH4

1 atom carbon

4 atoms hydrogen

CH4

1 atom carbon

4 atoms hydrogen

C3H4C3H4

Organic compoundsOrganic compounds

All compounds without the combination of carbon atoms All compounds without the combination of carbon atoms and other elements’ atoms are and other elements’ atoms are inorganic compoundsinorganic compounds..

Water, Carbon monoxide, Ammonia, Sulfuric Acid. Water, Carbon monoxide, Ammonia, Sulfuric Acid.

Inorganic CompoundsInorganic Compounds

Matter exists in four states: Matter exists in four states: solid, liquid, and gaseoussolid, liquid, and gaseous physical states and a fourth state known as physical states and a fourth state known as plasmaplasma. .

1.Water exists as ice, liquid, or water vapor depending on its 1.Water exists as ice, liquid, or water vapor depending on its temperature. temperature.

2.Plasma is a high-energy mixture of positively charged ions 2.Plasma is a high-energy mixture of positively charged ions and negatively charged electrons. It is the most abundant and negatively charged electrons. It is the most abundant form of matter in the universe, but very little is found on form of matter in the universe, but very little is found on Earth.Earth.

3. Scientists make artificial plasmas in fluorescent light, arc 3. Scientists make artificial plasmas in fluorescent light, arc lamps, neon signs, gas discharge lasers, and TV and lamps, neon signs, gas discharge lasers, and TV and computer screens.computer screens.

Four States of MatterFour States of Matter

Energy is the capacity to do work and transfer heat; it Energy is the capacity to do work and transfer heat; it moves matter.moves matter.

1.1. Kinetic energyKinetic energy has mass and speed; wind and has mass and speed; wind and electricity are examples.electricity are examples.

2. Potential energy2. Potential energy is stored energy, ready to be used: an is stored energy, ready to be used: an unlit match, for example.unlit match, for example.

Potential energy can be changed to kinetic energy: drop Potential energy can be changed to kinetic energy: drop an object, for example.an object, for example.

EnergyEnergy

Electromagnetic radiation is energy that travels as a wave, a result of Electromagnetic radiation is energy that travels as a wave, a result of changing electric and magnetic fields. changing electric and magnetic fields.

1.1. Each form of electromagnetic radiation has a different wavelength and Each form of electromagnetic radiation has a different wavelength and energy content. energy content.

2.2. The electromagnetic spectrum describes the range of electromagnetic The electromagnetic spectrum describes the range of electromagnetic waves that have different wavelengths and energy content.waves that have different wavelengths and energy content.

Electromagnetic radiationElectromagnetic radiation

Heat is the total kinetic energy of all moving atoms, ions, or Heat is the total kinetic energy of all moving atoms, ions, or molecules in a substance. molecules in a substance.

1.1. It can be transferred from one place to another by convection, It can be transferred from one place to another by convection, conduction, and radiation.conduction, and radiation.

2. Temperature is the average speed of motion of atoms, ions, or 2. Temperature is the average speed of motion of atoms, ions, or molecules in a sample of matter.molecules in a sample of matter.

3.3. Energy quality is measured by its usefulness. High energy is Energy quality is measured by its usefulness. High energy is concentrated and has high usefulness. Low energy is dispersed concentrated and has high usefulness. Low energy is dispersed and can do little work.and can do little work.

Heat and TemperatureHeat and Temperature

When matter has a physical change, its chemical composition is When matter has a physical change, its chemical composition is not changed; the molecules are organized in different patterns.not changed; the molecules are organized in different patterns.

In a chemical change, the chemical composition of the In a chemical change, the chemical composition of the elements/compounds change. Shorthand chemical equations elements/compounds change. Shorthand chemical equations represent what happens in the reaction.represent what happens in the reaction.

The Law of Conservation of Matter states that no atoms are The Law of Conservation of Matter states that no atoms are created/destroyed during a physical or chemical change. The created/destroyed during a physical or chemical change. The same is true for energy.same is true for energy.

1. Atoms are rearranged into different patterns/combinations.1. Atoms are rearranged into different patterns/combinations.2. Atoms can have physical or chemical changes, but they are 2. Atoms can have physical or chemical changes, but they are never created nor destroyed.never created nor destroyed.

The Law of Conservation of MatterThe Law of Conservation of Matter

Chemical equations are used to verify that no atoms are created or Chemical equations are used to verify that no atoms are created or destroyed in a chemical reaction. destroyed in a chemical reaction.

The number of atoms on one side of the equation must equal the The number of atoms on one side of the equation must equal the number of atoms on the other side of the equation.number of atoms on the other side of the equation.

HH22O O H H22 + O + O22

2H20 2H20 H H2 2 + O+ O22

2H2H220 0 2H 2H22 + O + O22

Chemical EquationsChemical Equations

Fig. 3-9 p. 44

Harmful PollutantsHarmful Pollutants

We will always have some pollutants, but we can We will always have some pollutants, but we can produce less and clean up some that we do produce less and clean up some that we do produce.produce.

1.1. Three factors determine the severity of a pollutant’s Three factors determine the severity of a pollutant’s harmful effects: harmful effects: chemical nature, concentration, and chemical nature, concentration, and persistencepersistence..

2.2. Dilution of concentration of a pollutant is only a Dilution of concentration of a pollutant is only a partial answer.partial answer.

3.3. Pollutants are classified into four categories based Pollutants are classified into four categories based on persistence: on persistence: degradable, biodegradable, slowly degradable, biodegradable, slowly degradable, and non-degradabledegradable, and non-degradable..

Energy efficiency/productivityEnergy efficiency/productivity measures the amount of useful work by measures the amount of useful work by a specific input of energy. Overall, energy efficiency is very poor—a specific input of energy. Overall, energy efficiency is very poor—about 16% of energy produces useful work.about 16% of energy produces useful work.

41% is unavoidable waste energy, and 43% is unnecessarily wasted 41% is unavoidable waste energy, and 43% is unnecessarily wasted energy. energy. A change in habits can further reduce this wasteA change in habits can further reduce this waste..

Energy Laws: Two Rules We Cannot BreakEnergy Laws: Two Rules We Cannot Break

The First Law of ThermodynamicsThe First Law of Thermodynamics states that energy can neither be states that energy can neither be created nor destroyed, but can be converted from one form to created nor destroyed, but can be converted from one form to another. another. The Second Law of ThermodynamicsThe Second Law of Thermodynamics states that when energy is states that when energy is changed from one form to another, there is always less usable changed from one form to another, there is always less usable energy. Energy quality is depleted.energy. Energy quality is depleted.

In changing forms of energy, there is a loss in energy quality; heat In changing forms of energy, there is a loss in energy quality; heat is often produced and lost.is often produced and lost.In living systems, solar energy is changed to chemical energy, then to In living systems, solar energy is changed to chemical energy, then to mechanical energy. High quality energy degrades to low quality heat.mechanical energy. High quality energy degrades to low quality heat.

A.A. Resource use automatically adds some waste heat/waste matter Resource use automatically adds some waste heat/waste matter to the environment.to the environment.

B.B. Advanced industrialized countries have high-throughput (high Advanced industrialized countries have high-throughput (high waste) economies.waste) economies.

1.1. Resources flow into planetary sinks (air, water, soil, organisms) Resources flow into planetary sinks (air, water, soil, organisms) with accumulation to harmful levels.with accumulation to harmful levels.2.2. Eventually consumption will exceed capacity of the Eventually consumption will exceed capacity of the

environment to dilute/degrade wastes.environment to dilute/degrade wastes.

Recycling/reusing more of Earth’s matter resources slows depletion Recycling/reusing more of Earth’s matter resources slows depletion of nonrenewable resources and reduces environmental impact.of nonrenewable resources and reduces environmental impact.

Shifting to a more sustainable, low-throughput (low-waste) Shifting to a more sustainable, low-throughput (low-waste) economy is the best long-term solution to environmental economy is the best long-term solution to environmental problems. problems.

Waste less matter; live more simply; and slow population growth.Waste less matter; live more simply; and slow population growth.

Energy Laws and Environmental ProblemsEnergy Laws and Environmental Problems

Next ClassNext Class

ECOSYSTEMS: ECOSYSTEMS: How do they workHow do they work

Chapter 4Chapter 4

Quiz Quiz 11