Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Lecture 3 Basic Chemistry

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Matter

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Matter  The “stuff” of the universe  Anything that has mass and takes up space  Weight and mass.  States of matter  Solid – has definite shape and volume e.g. bone  Liquid – has definite volume, changeable shape e.g. blood  Gas – has changeable shape and volume e.g. air

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Energy  The capacity to do work or put matter into motion  Energy has no mass,does not take up space.It can be measured by effect on matter.  Types of energy  Kinetic – energy in action  Potential – energy of position; stored (inactive) energy

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  Kinetic energy performs work by transferring motion to other matter – For example, water moving through a turbine generates electricity – Heat, or thermal energy, is kinetic energy associated with the random movement of atoms Copyright © 2009 Pearson Education, Inc.

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  An example of potential energy is water behind a dam – Chemical energy is potential energy because of its energy available for release in a chemical reaction Copyright © 2009 Pearson Education, Inc.

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Energy Form Conversions  Energy is easily converted from one form to another  During conversion, some energy is “lost” as heat e.g. body temperature, lit bulb.

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5.11 Two laws govern energy transformations  Energy transformations within matter are studied by individuals in the field of thermodynamics – Biologists study thermodynamics because an organism exchanges both energy and matter with its surroundings Copyright © 2009 Pearson Education, Inc.

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 5.11 Two laws govern energy transformations  It is important to understand two laws that govern energy transformations in organisms – The first law of thermodynamics—energy in the universe is constant – The second law of thermodynamics—energy conversions increase the disorder of the universe – Entropy is the measure of disorder, or randomness Copyright © 2009 Pearson Education, Inc.

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Fuel Gasoline Energy conversion in a cell Energy for cellular work Cellular respiration Waste productsEnergy conversion Combustion Energy conversion in a car Oxygen Heat Glucose Oxygen Water Carbon dioxide Water Carbon dioxide Kinetic energy of movement Heat energy

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Forms of Energy  Chemical – stored in the bonds of chemical substances e.g.ATP  Electrical – results from the movement of charged particles e.g. nerve impulse,  Mechanical – directly involved in moving matter  Radiant or electromagnetic – energy traveling in waves (i.e., visible light, ultraviolet light, and X-rays)

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Composition of Matter  Elements – unique substances that cannot be broken down by ordinary chemical means  Atoms – more-or-less identical building blocks for each element  Atomic symbol – one- or two-letter chemical shorthand for each element

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Properties of Elements  Each element has unique physical and chemical properties  Physical properties – those detected with our senses  Chemical properties – pertain to the way atoms interact with one another

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  What are the major elements of our body

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Major Elements of the Human Body  Oxygen (O)  Carbon (C)  Hydrogen (H)  Nitrogen (N)

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Lesser and Trace Elements of the Human Body  Lesser elements make up 3.9% of the body and include:  Calcium (Ca), phosphorus (P), potassium (K), sulfur (S), sodium (Na), chlorine (Cl), magnesium (Mg), iodine (I), and iron (Fe)

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Lesser and Trace Elements of the Human Body  Trace elements make up less than 0.01% of the body  They are required in minute amounts, and are found as part of enzymes

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Atomic Structure  The nucleus consists of neutrons and protons  Neutrons – have no charge and a mass of one atomic mass unit (amu)  Protons – have a positive charge and a mass of 1 amu  Electrons are found orbiting the nucleus  Electrons – have a negative charge and 1/2000 the mass of a proton (0 amu)

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Models of the Atom  Planetary Model – electrons move around the nucleus in fixed, circular orbits  Orbital Model – regions around the nucleus in which electrons are most likely to be found

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Models of the Atom Figure 2.1

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Magnesium Lithium Hydrogen Third shell First shell Second shell Sodium Beryllium Aluminum Boron Silicon Carbon Phosphorus Nitrogen Sulfur Oxygen Chlorine Fluorine Argon Neon Helium

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Identification of Elements  Atomic number – equal to the number of protons  Mass number – equal to the mass of the protons and neutrons  Atomic weight – average of the mass numbers of all isotopes

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Identification of Elements  Isotope – atoms with same number of protons but a different number of neutrons  Radioisotopes – atoms that undergo spontaneous decay called radioactivity

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Identification of Elements: Atomic Structure Figure 2.2

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Identification of Elements: Isotopes of Hydrogen Figure 2.3

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Why are the number of neutrons so important???  Isotopes = variant forms of the same element  Different # of neutrons  Different mass number  Naturally occurring  Virtually the same chemical properties  Unstable nuclei spontaneously release energy ~ radiation

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Radioactive Isotopes  Release detectable signals, so they can be used in tracing and tracking portions of atoms or molecules  Medical Applications:  Treatment (ex: cancer)  Diagnosis (tracers used in scans)  Sterilization (ionizing radiation)  Research  Dating fossils or items (Carbon 14 dating)

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Carbon 14 dating  99% of all carbon is C 12 (6 protons, 6 neutrons)  1% of all carbon is either: C 13 (6 protons and 7 neutrons) Or C 14 (6 protons and 8 neutrons)  Scientists date materials based on the ratio of C12:C13:C14 and the mathematical decay rate

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Molecules and Compounds  Molecule – two or more atoms held together by chemical bonds  Compound – two or more different kinds of atoms chemically bonded together

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Mixtures and Solutions  Mixtures – two or more components physically intermixed (not chemically bonded)  Solutions – homogeneous mixtures of components  Solvent – substance present in greatest amount  Solute – substance(s) present in smaller amounts

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Concentration of Solutions  Percent, or parts per 100 parts  Molarity, or moles per liter (M)  A mole of an element or compound is equal to its atomic or molecular weight (sum of atomic weights) in grams

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Colloids and Suspensions  Colloids (emulsions) – heterogeneous mixtures whose solutes do not settle out  Suspensions – heterogeneous mixtures with visible solutes that tend to settle out

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Mixtures Compared with Compounds  No chemical bonding takes place in mixtures  Most mixtures can be separated by physical means  Mixtures can be heterogeneous or homogeneous  Compounds cannot be separated by physical means  All compounds are homogeneous

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