Slides 1 to 74 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Chapter 2 Atoms and Bonds

Matter: Atoms and Molecules Smallest unit of an element Subatomic particles Protons: (+) charge Neutrons: neutral Electrons: (-) charge Figure 2-1

Matter: Atoms and Molecules Structure of an atom Nucleus Protons Neutrons Electron Shell Figure 2-2(b)

Matter: Atoms and Molecules Atoms and Electron Shells Figure 2-3

Matter: Atoms and Molecules Atomic number Equals number of protons Atomic mass Equals protons + neutrons Isotopes of element Reflects number of neutrons Atomic weight Averages isotope abundance Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Matter: Atoms and Molecules All matter is composed of atoms in various combinations. Their interactions establish the foundations of anatomy and physiology at the cellular level. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Matter: Atoms and Molecules Chemical Bonds and Compounds Atoms bond in chemical reactions Reactions transfer electrons Electrons are gained, lost, or shared Molecules or compounds result Compounds contain several elements Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Matter: Atoms and Molecules Ionic Bonds Atoms gain or lose electrons Charged atoms are ions Ions bear (+) or (-) charge Cations have (+) charge Anions have (-) charge Cations and anions attract Ions form bonds Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Matter: Atoms and Molecules Ionic Bonding Figure 2-4(a)

Matter: Atoms and Molecules Sodium chloride crystal Figure 2-4(b)

Matter: Atoms and Molecules Table 2-2

Matter: Atoms and Molecules Covalent bonds Some atoms share electrons Shared electrons complete outer shell Sharing atoms bond covalently Single covalent bond One shared electron Double covalent bond Two shared electrons Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Matter: Atoms and Molecules Covalent Bonds Figure 2-5

Matter: Atoms and Molecules Nonpolar and Polar Covalent Bonds Equal electron sharing Nonpolar covalent bonds Example: carbon-carbon bonds Non-equal electron sharing Polar covalent bonds Example: oxygen-hydrogen bonds Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Matter: Atoms and Molecules Hydrogen bonds Weak attractive force Between 2 neighboring atoms A polar-bonded hydrogen A polar-bonded oxygen or nitrogen For example, between water molecules Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Matter: Atoms and Molecules Hydrogen Bonds Figure 2-6

Inorganic Compounds Water and its properties Most important body chemical Excellent solvent High heat capacity Essential chemical reactant Surface Tension Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings