1. Matter and Energy  Matter—anything that occupies space and has mass (weight)  Energy—the ability to do work  Chemical  Electrical  Mechanical  Radiant

2. Composition of Matter  Elements—fundamental units of matter  96% of the body is made from four elements Carbon (C) Oxygen (O) Hydrogen (H) Nitrogen (N)  Atoms—building blocks of elements

3. Atomic Structure  Nucleus  Protons (p + )  Neutrons (n 0 )  Outside of nucleus  Electrons (e - ) Figure 2.1

4. Identifying Elements  Atomic number—equal to the number of protons that the atom contains  Atomic mass number—sum of the protons and neutrons

5. Isotopes and Atomic Weight  Isotopes  Have the same number of protons  Vary in number of neutrons Figure 2.3

6. Radioactivity  Radioisotope  Heavy isotope  Tends to be unstable  Decomposes to more stable isotope  Radioactivity—process of spontaneous atomic decay  Isotopes in Medicine Isotopes in Medicine

7. Molecules and Compounds  Molecule—two or more like atoms combined chemically  Compound—two or more different atoms combined chemically Figure 2.4

8. Electrons and Bonding  Electrons occupy energy levels called electron shells  Electrons closest to the nucleus are most strongly attracted  Each shell has distinct properties  The number of electrons has an upper limit  Shells closest to the nucleus fill first  Bonding involves interactions between electrons in the outer shell (valence shell)

9. Inert Elements Figure 2.5a

10. Figure 2.5b Reactive Elements  Valence shells are not full and are unstable  Tend to gain, lose, or share electrons  Allow for bond formation, which produces stable valence

11. Chemical Bonds  Ionic bonds  Form when electrons are completely transferred from one atom to another  Ions  Charged particles Anions are negative Cations are positive Either donate or accept electrons

12. Ionic Bonds Figure 2.6 +– Sodium atom (Na) (11p + ; 12n 0 ; 11e – ) Chlorine atom (Cl) (17p + ; 18n 0 ; 17e – ) Sodium ion (Na + )Chloride ion (Cl – ) Sodium chloride (NaCl) ClNaCl Na

13. Ionic Bonds Figure 2.6, step 1 Sodium atom (Na) (11p + ; 12n 0 ; 11e – ) Chlorine atom (Cl) (17p + ; 18n 0 ; 17e – ) Cl Na

14. Ionic Bonds Figure 2.6, step 2 Sodium atom (Na) (11p + ; 12n 0 ; 11e – ) Chlorine atom (Cl) (17p + ; 18n 0 ; 17e – ) Cl Na

15. Ionic Bonds Figure 2.6, step 3 +– Sodium atom (Na) (11p + ; 12n 0 ; 11e – ) Chlorine atom (Cl) (17p + ; 18n 0 ; 17e – ) Sodium ion (Na + )Chloride ion (Cl – ) Sodium chloride (NaCl) ClNaCl Na

16. Covalent Bonds Figure 2.7a

17. Examples of Covalent Bonds Figure 2.7b

18. Examples of Covalent Bonds Figure 2.7c

19. Polarity  Covalently bonded molecules  Some are non-polar Electrically neutral as a molecule  Some are polar Have a positive and negative side Figure 2.8

20. Hydrogen Bonds  Weak chemical bonds  Hydrogen is attracted to the negative portion of polar molecule  Provides attraction between molecules

21. Hydrogen Bonds Figure 2.9

22. Patterns of Chemical Reactions  Synthesis reaction (A + B  AB)  Atoms or molecules combine  Energy is absorbed for bond formation  Decomposition reaction (AB  A + B)  Molecule is broken down  Chemical energy is released

23. Synthesis Reactions Figure 2.10a

24. Decomposition Reactions Figure 2.10b

25. Exchange Reactions  Exchange reaction (AB + C  AC + B)  Involves both synthesis and decomposition reactions  Switch is made between molecule parts and different molecules are made

26. Exchange Reactions Figure 2.10c