1. Chemistry and the environment
Chemistry is central to environmental science:
• Carbon dioxide and climate change
• Sulfur dioxide and acid rain
• Pesticides and public health
• Nitrogen and wastewater treatment
• Ozone and its atmospheric depletion

2. Atoms and elements
An element is a fundamental type of chemical substance.
Elements are composed of atoms.
Each atom has a certain number of:
protons (+ charge)
electrons (– charge)
neutrons (no charge)
Figure 4.1

3. Atoms and elements
92 elements occur in nature, each with its characteristic number of protons, neutrons, and electrons.
Figure 4.1

4. Chemical symbols Each element is abbreviated with a chemical symbol:
H = hydrogen
C = carbon
N = nitrogen
O = oxygen
P = phosphorus
Cl = chlorine
Fe = iron
CHOPKINS CaFe

5. Isotopes
Isotopes are alternate versions of elements, which differ in mass by having a different number of neutrons.
Carbon-14 has two extra neutrons beyond normal carbon’s 6.
Figure 4.2

6. Ions Atoms electrically charged, due to gain or loss of electrons
Figure 4.3

7. Molecules, compounds, and bonds
Molecules = combinations of two or more atoms
Compounds = molecules consisting of multiple elements
Atoms are held together by bonds:
covalent bond = uncharged atoms sharing electrons (CO2)
ionic bond = charged atoms held together by electrical attraction (NaCl)

8. Water is a unique compound
Hydrogen bonds give water properties that make it a vital molecule for life:
• Is cohesive
• Resists temperature change
• Ice insulates
• Dissolves many chemicals
Figure 4.4

9. Acidity In an aqueous solution,
If H+ concentration is greater than OH– concentration,
then solution is acidic.
If OH– is greater than H +,
then solution is basic.

10. pH scale pH scale measures acidity and basicity. Pure water = 7
Acids < 7
Bases > 7
Figure 4.6

11. pH Scale

12. Organic compounds
Consist of carbon atoms and, generally, hydrogen atoms
Joined by covalent bonds
May include other elements
Highly diverse; C can form many elaborate molecules
Vitally important to life
ethane

13. Hydrocarbons
C and H only; major type of organic compound Mixtures of hydrocarbons make up fossil fuels.
Figure 4.7

14. Macromolecules Large molecules essential for life: • Proteins
• Nucleic acids
• Carbohydrates
• Lipids
The first three are polymers, long chains of repeated molecules.

15. Proteins
Consist of chains of amino acids; fold into complex shapes For structure, energy, immune system, hormones, enzymes

16. Protein Examples

17. Carbohydrates
Complex carbohydrates consist of chains of sugars. For energy, also structural (cellulose, chitin)

18. Lipids Do not dissolve in water • Fats and oils • Phospholipids
• Waxes
• Steroids

19. Triglyceride

20. Nucleic acids DNA and RNA
Encode genetic information and pass it on from generation to generation
DNA = double-stranded chain (double helix)
RNA = single-stranded chain

21. Nucleic acids
Paired strands of nucleotides make up DNA’s double helix.
Figure 4.9

22. Genes and heredity
Genes, functional stretches of DNA, code for the synthesis of proteins.
Figure 4.10

23. Cells
Basic unit of organismal organization; compartmentalize macromolecules and organelles
Plant cell
Animal cell
Prokaryotic cell
Eukaryotic cell
Figure 4.12

24. Energy and Matter
Energy can change the position, physical composition, or temperature of matter
What again is matter?

25. Matter
Matter—anything that occupies space and has mass Matter may exist as one of three states: Solid: definite shape and volume Liquid: definite volume; shape of container Gaseous: neither a definite shape nor volume

26. Matter and Energy
Matter may be changed Physically Changes do not alter the basic nature of a substance Chemically Changes alter the chemical composition of a substance

27. Forms of Energy
Chemical energy is stored in chemical bonds Electrical energy results from movement of charged particles Mechanical energy is energy directly involved in moving matter Radiant energy travels in waves (light/heat)

28. Identify examples of potential and kinetic energy in these pictures.
Matter and Energy
Energy—the ability to do work. Has no mass and does not take up space Kinetic energy: energy is doing work Potential energy: energy is inactive; stored
Identify examples of potential and kinetic energy in these pictures.

29. Potential and kinetic energy
Potential energy stored in food is converted to kinetic energy when we exercise.

30. Chemical Potential Energy (CPE)

31. Energy and Human Life