1. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Matter  Matter - has mass and takes up space  States of matter: Solid, Liquid,Gas  Elements – unique physical and chemical properties; 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

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

3. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Chemical Bonds  Molecule – two or more atoms held together by chemical bonds  Compound – two or more different kinds of atoms chemically bonded together  Bonds are formed using the electrons in the outermost energy level, Valence shell  Octet rule – except for the first shell which is full with two electrons, atoms interact in a manner to have eight electrons in their valence shell

4. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Chemically Inert Elements  Inert elements have their outermost energy level fully occupied by electrons Figure 2.4a

5. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Chemically Reactive Elements  Reactive elements do not have their outermost energy level fully occupied by electrons Figure 2.4b

6. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Types of Chemical Bonds  Ionic  Covalent  Hydrogen

7. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Ionic Bonds  Ions are charged atoms resulting from the gain or loss of electrons  Anions (negative ions) have gained one or more electrons  Cations (positive ions) have lost one or more electrons

8. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Covalent Bonds  Covalent bonds are formed by the sharing of two or more electrons produces molecules

9. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Double Covalent Bonds Figure 2.7b

10. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Triple Covalent Bonds Figure 2.7c

11. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Nonpolar and Polar Molecules  Electrons shared equally - nonpolar molecules - nonpolar covalent bond  Unequal sharing of electrons - polar molecules - polar covalent bond  Hydrogen bonds

12. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.7

13. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hydrogen Bonds  weak bond  Responsible for surface tension in water  Important as intramolecular bonds  Proteins, DNA & RNA

14. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.8

15. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Comparison of Ionic, Polar Covalent, and Nonpolar Covalent Bonds Figure 2.9

16. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Chemical Reactions  Occur when chemical bonds are formed, rearranged, or broken  Chemical equations contain:  Number and type of reacting substances, and products produced  Relative amounts of reactants and products

17. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.13

18. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Patterns of Chemical Reactions  Synthesis reactions A + B  AB  Decomposition reactions: Molecules are broken down into smaller molecules AB  A + B  All chemical reactions are theoretically reversible A + B  AB AB  A + B  Catalysts – increase the rate of a reaction without being chemically changed  Enzymes – biological catalysts