Biology - Chapter 3

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Biology - Chapter 3Introduction to Chemistry

• Charles Page High School
• Stephen L. Cotton

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Section 3.1The Nature of Matter

• Objectives
• Identify several important properties of matter.

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Section 3.1The Nature of Matter

• Objectives
• Compare physical and chemical properties.

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Section 3.1The Nature of Matter

• Questions
• What are living things made of?
• Are there any special substances found in living
  things, but not found in nonliving things?
• To answer these questions, we must examine the
  world around usa world made up of matter and
  energy!

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Section 3.1The Nature of Matter

• Properties of Matter matter is all around us
  everything we see, touch, or smell
• Matter is anything that has mass and occupies
  volume
• Mass- the quantity of matter in an object
• Volume- amount of space taken up

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Section 3.1The Nature of Matter

• Mass is closely related to weight, a measure of
  gravity on an object
• Mass is constant weight changes due to different
  locations and gravity
• Matter also has other physical properties such
  as color, odor, shape, texture, taste, hardness

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Section 3.1The Nature of Matter

• Two other physical properties
• melting point and boiling point
• Physical properties- can be measured without
  changing the identity of the matter
• Chemical properties- describe the ability to
  change into another material due to a chemical
  change

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Section 3.1The Nature of Matter

• A chemical change is difficult to reverse
• lump of coal that has been burned
• Phases of matter
• physical states are gases, liquids, solids
• change from one to another is physical
• water is still water regardless of the physical
  state ice (solid), liquid, or vapor (gas stage)

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Section 3.2Composition of Matter

• Objectives
• Describe the structure of an atom.

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Section 3.2Composition of Matter

• Objectives
• Compare elements and compounds.

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Section 3.2Composition of Matter

• Objectives
• Discuss the uses of radioactive isotopes.

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Section 3.2Composition of Matter

• Think of breaking a piece of chalk.
• Greek philosopher Democritus, nearly 3000 years
  ago - piece of chalk?
• called the elementary particles atoms from the
  Greek word atomos, meaning unable to be cut
• not an experimental approach thus poor science-
  no follow up

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Section 3.2Composition of Matter

• The Atom
• the basic unit of matter very small
• contains even smaller particles (gt200!)
• 3 principal subatomic particles we will study
  are protons, neutrons, electrons
• Atomic structure
• center is called the nucleus- very small, but is
  most of the mass of the atom

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Section 3.2Composition of Matter

• Nucleus made of 2 particles
• protons- positively charged
• neutrons- electrically neutral
• proton and neutron are about equal in mass to
  each other (1 atomic mass unit)
• Third particle electron- negative charge, very
  lightweight travel outside the nucleus in energy
  levels
• Fig. 3-6, page 48

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Section 3.2Composition of Matter

• The number of negative charged electrons the
  number of positive charged protons thus the atom
  is neutral as a whole!
• Atomic number the number of protons
• identifies an atom a unique number
• Mass number protons neutrons (electrons are
  too light to contribute much)

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Section 3.2Composition of Matter

• Chemical Elements consist of entirely one type of
  atom
• about 90 naturally occur others are man-made
• represented by a chemical symbol, one or two
  letters from the name, some from Latin or Greek
  (ex. Pb is plumbum)
• Fig. 3-8, page 49

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Section 3.2Composition of Matter

• Most elements are solids C, Fe, S, Ca
• Few are gases H, O, N, Cl
• Very few are liquids Hg, Br
• Isotopes atoms with the same atomic number
  (protons), but different number of neutrons
• Examples Protium, Deuterium, Tritium are all
  isotopes of Hydrogen
• Fig. 3-9, page 50

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Section 3.2Composition of Matter

• Radioactive Isotopes some nuclei are unstable,
  and release particles called radiation
• Many practical uses
• study living organisms diagnose and treat
  disease sterilize foods measure the age of
  certain rocks

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Section 3.2Composition of Matter

• Radioactive isotopes may be used as tracers in
  diagnosing diseases
• iodine-131 function of thyroid gland
• sodium-24 diseases of circulatory system
• iron-59 study blood circulation
• Also treat certain diseases
• cobalt-60 cancer radiation treatment
• carbon-14 treat brain tumors

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Section 3.2Composition of Matter

• Other uses of radioactive isotopes
• kill bacteria that cause food spoilage
• measuring age of certain rocks
• However, they must be handled with great care
• can damage or kill living things
• be aware of radiation in the environment

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Section 3.2Composition of Matter

• Chemical compounds when two or more different
  kinds of elements combine (chemically) to form a
  totally new material
• most things around us are compounds
• have a definite proportion of elements
• also represented by a chemical formula
• NaCl H2SO4

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Section 3.3Interactions of Matter

• Objectives
• Explain how electron arrangement determines an
  atoms reactivity.

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Section 3.3Interactions of Matter

• Objectives
• Describe the two types of chemical bonds.

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Section 3.3Interactions of Matter

• Chemical compounds are formed by the interactions
  of individual atoms
• called chemical bonding
• formed in very definite ways, according to
  certain rules
• Each energy level can hold only a certain number
  of electrons (outer level has 8 maximum)
• Fig. 3-12, page 52

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Section 3.3Interactions of Matter

• When the outermost level has the maximum number
  allowed, it is very stable- such compounds do not
  usually further react
• In order to achieve stability, an atom can a)
  gain electrons, b) lose electrons, or c) share
  electrons
• This is done so that both atoms will become full-
  thus stable!

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Section 3.3Interactions of Matter

• Ionic Bonds due to a transfer (loss or gain) of
  electrons, forming an ionic bond
• Forms ions- or charged particles
• Normally between a metal (which loses electrons
  easily) and a nonmetal (which gains electrons
  easily)
• Consider Sodium Chlorine

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Section 3.3Interactions of Matter

• Fig. 3-13, page 53
• Covalent Bond due to the sharing of electrons
  between atoms
• by sharing, each atoms fills its outer level
• Consider water and carbon dioxide
• Fig. 3-15, page 54
• resulting particle called molecule
• New properties of a compound!

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Section 3.4Chemical Reactions

• Objectives
• Identify the substances involved in a chemical
  reaction.

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Section 3.4Chemical Reactions

• Objectives
• Describe the role of energy in chemical
  reactions.

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Section 3.4Chemical Reactions

• Chemical Reaction any process in which a
  chemical change occurs
• difficult to reverse
• new physical and chemical properties
• occur all the time, very much a part of our daily
  lives
• some are slow, like rusting
• others fast, like a firecracker blasting

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Section 3.4Chemical Reactions

• Always 2 types of materials
• starting materials (called reactants)
• final materials (called products)
• Reaction described by an equation
• O2 2H2 ? 2H2O
• the plus sign joins the reactants, the arrow read
  as yields or equals
• can be reversible not normally done

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Section 3.4Chemical Reactions

• The most important factor in whether a reaction
  occurs is ENERGY.
• Reactions that release energy will occur
  spontaneously
• those that require energy will not occur without
  a source of energy
• Why is this significant? Living things carry on
  both types of reactions