Why study chemistry in an anatomy and physiology course? The answer is simple. Your entire body is made up of chemicals, thousands of them, continuously interacting with one another at an incredible pace. Although it is possible to study anatomy without much reference to chemistry, chemical reactions underlie all physiological processes—movement, digestion, the pumping of your heart, and even your thoughts. This chapter presents the basic chemistry and biochemistry (the chemistry of living material) you need to understand body functions.
Trang 1Part A Chemistry Comes Alive
Trang 7 Atoms
◦ Unique building blocks for each element
Atomic symbol: one or twoletter chemical shorthand for each element
Eg: Copper Cu Sulfur S
Iron Fe Potassium K
Mercury Hg Phosphorus P
Gold Au Iodine I
Trang 9 About 3.9% of body mass:
◦ calcium (Ca), phosphorus (P), potassium (K), sulfur (S), sodium (Na), chlorine (Cl),
magnesium (Mg), iodine (I), and iron (Fe)
Trang 10 < 0.01% of body mass:
◦ Part of enzymes, e.g., chromium (Cr), manganese (Mn), and zinc (Zn)
Trang 11 Determined by numbers of subatomic particles
Nucleus consists of neutrons and protons
Trang 14 Planetary model
◦ Depicts fixed circular electron paths
◦ Useful for illustrations (as in the text)
Trang 15Copyright © 2010 Pearson Education, Inc. Figure 2.1
(a) Planetary model (b) Orbital model
Trang 16 Atoms of different elements contain different numbers of subatomic particles
◦ Compare hydrogen, helium and lithium (next slide)
Trang 17Copyright © 2010 Pearson Education, Inc. Figure 2.2
Proton
Neutron
Electron
Helium (He) (2p + ; 2n 0 ; 2e – )
Lithium (Li) (3p + ; 4n 0 ; 3e – ) Hydrogen (H)
(1p + ; 0n 0 ; 1e – )
Trang 18 Atomic number = number of protons in nucleus
Trang 19 Atomic weight = mass of the protons and neutrons
Trang 20
Copyright © 2010 Pearson Education, Inc. Figure 2.3
Proton Neutron Electron
Deuterium ( 2 H) (1p + ; 1n 0 ; 1e – )
Tritium ( 3 H) (1p + ; 2n 0 ; 1e – ) Hydrogen ( 1 H)
(1p + ; 0n 0 ; 1e – )
Trang 21 Spontaneous decay (radioactivity)
Similar chemistry to stable isotopes
Can be detected with scanners
Trang 22 Valuable tools for biological research and medicine
Cause damage to living tissue:
◦ Useful against localized cancers
◦ Radon from uranium decay causes lung cancer
Trang 25 Solutions are homogeneous mixtures
Usually transparent, e.g., atmospheric air or seawater
Trang 27Copyright © 2010 Pearson Education, Inc. Figure 2.4
Solution
Solute particles
Solute particles
Solute particles
Solute particles are very tiny, do not settle out or scatter light.
Colloid
Solute particles are larger than in a solution and scatter light; do not settle out.
Trang 30 Stable and unreactive
Outermost energy level fully occupied or contains eight electrons
Trang 31Copyright © 2010 Pearson Education, Inc. Figure 2.5a
Helium (He) (2p + ; 2n 0 ; 2e – )
Neon (Ne) (10p + ; 10n 0 ; 10e – )
Outermost energy level (valence shell) complete
Trang 32 Outermost energy level not fully occupied by electrons
Tend to gain, lose, or share electrons (form bonds) with other atoms to achieve stability
Trang 33Copyright © 2010 Pearson Education, Inc. Figure 2.5b
2e 4e
2e 8e 1e
Outermost energy level (valence shell) incomplete
Hydrogen (H) (1p + ; 0n 0 ; 1e – )
Carbon (C) (6p + ; 6n 0 ; 6e – ) 1e
Oxygen (O) (8p + ; 8n 0 ; 8e – ) Sodium (Na)
(11p + ; 12n 0 ; 11e – ) 2e 6e
Trang 34 Ionic
Covalent
Hydrogen
Trang 35 Ions are formed by transfer of valence shell electrons between atoms
◦ Anions (– charge) have gained one or more electrons
◦ Cations (+ charge) have lost one or more electrons
Attraction of opposite charges results in an ionic bond
Trang 36Copyright © 2010 Pearson Education, Inc. Figure 2.6a-b
Sodium atom (Na)
(11p + ; 12n 0 ; 11e – )
Chlorine atom (Cl) (17p + ; 18n 0 ; 17e – )
Sodium chloride (NaCl)
(a) Sodium gains stability by losing one electron, and
chlorine becomes stable by gaining one electron
(b) After electron transfer, the oppositely charged ions formed attract each other.
Trang 37 Ionic compounds form crystals instead of individual molecules
◦ NaCl (sodium chloride)
Trang 38Copyright © 2010 Pearson Education, Inc. Figure 2.6c
Trang 39 Formed by sharing of two or more valence shell electrons
Allows each atom to fill its valence shell at least
part of the time
Trang 40Copyright © 2010 Pearson Education, Inc. Figure 2.7a
+
Hydrogen
atoms
Carbon atom
Molecule of methane gas (CH 4 )
Structural formula shows single bonds.
(a) Formation of four single covalent bonds:
carbon shares four electron pairs with four hydrogen atoms.
or
Resulting molecules Reacting atoms
Trang 41Copyright © 2010 Pearson Education, Inc. Figure 2.7b
or
Oxygen
atom
Oxygen atom
Molecule of oxygen gas (O 2 )
Structural formula shows double bond.
(b) Formation of a double covalent bond: Two oxygen atoms share two electron pairs.
Resulting molecules Reacting atoms
+
Trang 42Copyright © 2010 Pearson Education, Inc. Figure 2.7c
Nitrogen
atom
Nitrogen atom
Molecule of nitrogen gas (N 2 )
Structural formula shows triple bond.
(c) Formation of a triple covalent bond: Two nitrogen atoms share three electron pairs.
Resulting molecules Reacting atoms
Trang 43 Sharing of electrons may be equal or unequal
◦ Equal sharing produces electrically balanced nonpolar molecules
CO 2
Trang 44Copyright © 2010 Pearson Education, Inc. Figure 2.8a
Trang 45 Unequal sharing by atoms with different electronattracting abilities produces polar molecules
Trang 46Copyright © 2010 Pearson Education, Inc. Figure 2.8b
Trang 47Copyright © 2010 Pearson Education, Inc. Figure 2.9
Trang 48 Attractive force between electropositive hydrogen
of one molecule and an electronegative atom of another molecule
Trang 49Copyright © 2010 Pearson Education, Inc.
(a) The slightly positive ends ( + ) of the water molecules become aligned with the slightly negative ends ( –) of other water molecules
+ –
–
–
+ +
+
+ +
Hydrogen bond (indicated by dotted line)
Figure 2.10a
Trang 50 Occur when chemical bonds are formed, rearranged, or broken
Represented as chemical equations
Chemical equations contain:
◦ Molecular formula for each reactant and product
◦ Relative amounts of reactants and products, which should balance
Trang 51H + H H2 (hydrogen gas)4H + C CH4 (methane)
Trang 52 Synthesis (combination) reactions
Decomposition reactions
Exchange reactions
Trang 53 A + B AB
◦ Always involve bond formation
◦ Anabolic
Trang 54Copyright © 2010 Pearson Education, Inc. Figure 2.11a
Example
Amino acids are joined together to form a protein molecule
(a) Synthesis reactions
Smaller particles are bonded together to form larger, more complex molecules.
Amino acid molecules
Protein molecule
Trang 55 AB A + B
◦ Reverse synthesis reactions
◦ Involve breaking of bonds
◦ Catabolic
Trang 56Copyright © 2010 Pearson Education, Inc. Figure 2.11b
(b) Decomposition reactions
Glucose molecules Glycogen
Trang 57 AB + C = AC + B
AB + CD = AD + CB
◦ Also called displacement reactions
◦ Bonds are both made and broken
Trang 58Copyright © 2010 Pearson Education, Inc. Figure 2.11c
Adenosine diphosphate (ADP)
Glucose phosphate
+ +
Trang 59 Decomposition reactions: Reactions in which fuel
is broken down for energy
Also called exchange reactions because electrons are exchanged or shared differently
◦ Electron donors lose electrons and are oxidized
◦ Electron acceptors receive electrons and become
reduced
Trang 62◦Enzymes are biological catalysts