1. 2
Basic Chemistry

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

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

4. Subatomic Particles Nucleus Protons (p+) Neutrons (n0)
Orbiting the nucleus
Electrons (e–)
Number of protons equals numbers of electrons in an atom

5. Nucleus Nucleus Helium atom Helium atom 2 protons (p+) 2 neutrons (n0)
2 electrons (e–)
2 protons (p+)
2 neutrons (n0)
2 electrons (e–)
(a) Planetary model
(b) Orbital model
KEY:
= Proton
= Electron
= Neutron
= Electron cloud
Figure 2.1

6. Figure 2.2

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

8. Isotopes and Atomic Weight
Atoms of the same element with the same number of protons and the same atomic number
Vary in number of neutrons

9. Figure 2.3

10. Isotopes and Atomic Weight
Close to mass number of most abundant isotope
Atomic weight reflects natural isotope variation

11. Radioactivity Radioisotope Heavy isotope Tends to be unstable
Decomposes to more stable isotope
Radioactivity—process of spontaneous atomic decay

12. Molecules and Compounds
Molecule—two or more atoms of the same elements combined chemically
Compound—two or more atoms of different elements combined chemically

13. Figure 2.4

14. Chemical Reactions Atoms are united by chemical bonds
Atoms dissociate from other atoms when chemical bonds are broken

15. 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

16. Electrons and Bonding
Bonding involves interactions between electrons in the outer shell (valence shell)
Full valence shells do not form bonds

17. Inert Elements
Atoms are stable (inert) when the outermost shell is complete
How to fill the atom’s shells
Shell 1 can hold a maximum of 2 electrons
Shell 2 can hold a maximum of 8 electrons
Shell 3 can hold a maximum of 18 electrons

18. Inert Elements
Atoms will gain, lose, or share electrons to complete their outermost orbitals and reach a stable state
Rule of eights
Atoms are considered stable when their outermost orbital has 8 electrons
The exception to this rule of eights is Shell 1, which can only hold 2 electrons

19. Figure 2.5a

20. 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

21. Figure 2.5b

22. Chemical Bonds Ionic bonds
Atoms become stable through the transfer of electrons
Form when electrons are completely transferred from one atom to another
Ions
Result from the loss or gain of electrons
Anions are negative due to gain of electron(s)
Cations are positive due to loss of electron(s)

23. Figure 2.6

24. Figure 2.6, step 1

25. Figure 2.6, step 2

26. Figure 2.6, step 3

27. Chemical Bonds Covalent bonds
Atoms become stable through shared electrons
Electrons are shared in pairs
Single covalent bonds share one pair of electrons
Double covalent bonds share two pairs of electrons

28. Figure 2.7a

29. Figure 2.7b

30. Figure 2.7c

31. Covalent Bonds Covalent bonds are either nonpolar or polar Nonpolar
Electrons are shared equally between the atoms of the molecule
Electrically neutral as a molecule

32. Figure 2.8a

33. Covalent Bonds Covalent bonds are either nonpolar or polar Polar
Electrons are not shared equally between the atoms of the molecule
Have a positive and negative side or pole

34. Figure 2.8b

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

36. + H H O –
Hydrogen bonds + H O + H – – – H H O O + + H H H + O H –
(a)
(b)
Figure 2.9

37. 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

38. Figure 2.10a

39. Figure 2.10b

40. Patterns of Chemical Reactions
Exchange reaction (AB + CAC + B)
Involves both synthesis and decomposition reactions
Switch is made between molecule parts and different molecules are made

41. Figure 2.10c

42. Biochemistry: Essentials for Life
Organic compounds
Contain carbon
Most are covalently bonded
Includes carbohydrates, lipids, proteins, nucleic acids
Inorganic compounds
Lack carbon
Tend to be simpler compounds
Includes water, salts, and some acids and bases