Chemistry of Life

1. Chemistry of Life Chapter 2

2. Matter • Matter is anything that takes up space and has mass. • All living and non-living things are made up of matter • Chemistry is important to understanding of how biological processes occur in living things. • You must know basic chemical principles to understand science

3. Composition of MatterELEMENTS • Elements are found on the periodic table. • Element – cannot be broken down any further without losing the properties of the material • Elements are made up of atoms • Atoms are made up of Subatomic particles • Neutron – no charge, found in the nucleus • Proton – positive charge, found in the nucleus • Electron – negative charge, orbits around the nucleus

4. Atomic structure • Nucleus contains protons and neutrons • Electrons fly around it.

6. Composition of Matter • Atomic number – the number of protons, determines what element it is • Atomic mass • Sum of the number of protons and neutrons • Electrons are so tiny they do not contribute to mass • Isotope • Element with same number of protons, but a different number of neutrons (mass is different!)

7. Compounds • Made up of atoms of two or more elements in a fixed proportion • Most elements do not exist alone in nature • Forming compounds changes the chemical properties • Example: Sodium reacts with water in the air and explodes. Chlorine is a poisonous gas. But when in compound (NaCl) is makes food tasty, and is harmless!

8. Compounds • Elements alone are usually not stable • They want to be stable, so they will combine with other elements to form compounds • Elements want their pockets full (their outer electron shell) usually 8 electrons! • In order to accomplish this, they must bind with other elements (or sometimes an element of the same type)

9. Chemical Bonding • Ionic bonds • Donate/receive electrons from another element • Metal to non-metal • Covalent bonds • Sharing of electrons, does not have to be equal • Polarity • Polar covalent bonds have unequal sharing of electrons • This results in a partial charge on the atom

10. Ionic or covalent? • 1. I2 • 2. LiF • 3. O2 • 4. CaCl • 5. NO3

11. Topic: Energy • 1. In order to start a car engine, what has to ignite the gas ? • 2. A car uses gas to go and creates carbon monoxide gas. What are the reactants and products and energy source in this process? • 3. How are enzymes and catalysts related? TIL:

12. Energy All living things require energy to carry out daily processes Energy exists in many forms, and can be changed into different forms • In biology, the important forms of energy are: • Chemical (breaking down food) • Thermal (heat) • Electrical (nerve impulses) • Mechanical (movement)

13. Energy • Energy is absorbed or released when chemical bonds are broken and formed • Exergonic reactions – release energy • Endergonic reactions – absorb energy • Metabolism – all of the chemical reactions involving energy in the body

14. Activation Energy • Most chemical reactions in the body require energy input in order to start the reaction • Catalysts are substances that help reduce the amount of energy required to start the reaction • Enzymes are the main biological catalysts in the body • Enzymes are proteins (and RNA)

15. Energy • Without biological catalysts, most of the reactions that occur in the body cannot occur or occur too slowly to sustain life • Enzymes are not part of the reaction, and are reusable

16. REVIEW • What is the name of the energy that starts biological chemical reactions? • What is the name of the catalyst found in the human body? • What does the catalyst do in chemical reactions?

17. Chemical Reactions-where is the energy? Na + Cl Na Cl Reactants Product 2HCl  H2 + 2Cl Reactant Products 2H2O  2H2 + O2

18. Chemical Reactions-Can go both directions! Reactants and Products CO2 + H2O H2CO3 Carbon dioxide water carbonic acid Your cells create carbon dioxide as a waste product. It crosses the cell membrane into the blood. The blood has water in it. A reaction changes it to carbonic acid in the blood. Blood goes to the lungs, CO2 diffuses out of the blood, into the alveoli of the lung and water is left behind in the blood, replaced with O2, which diffuses in to replace the CO2. (book pg. 36)

19. Water & Solutions

20. Importance of Water • Your body is 60-70% water • Water’s unique properties are due to the structure of the molecule • Water is a polar covalent molecule • This results in a partial charge on the molecule • Polarity of water allows water to dissolve other polar molecules • Dissolved particles are critical to daily functioning in biological systems

21. Water • The polarity of water also causes it to be “sticky” • Water is attracted to other water molecules (adhesion) • Water is also attracted to other surfaces (cohesion) • These two properties along with capillary action allow water (and aqueous solutions) to move upward against gravity

22. Water • Water also has a high specific heat. • This means that water can absorb large amounts of energy and only change temperature a small amount • This is important in controlling body temperature • Also important in regulating temperature of the Earth (our external environment)

23. Solutions • Mixture of one or more substances • Can be solid, liquid or gas • Solute – substance being dissolved • Solvent – substance doing the dissolving • Saturated solution • Solution in which the max amount of solute is dissolved

24. Solutions • Aqueous solution – a solution in which water is the solvent • Our body cells are in aqueous solution (remember that the majority of our body and cells are water) • Water helps us maintain homeostasis (a balanced internal environment)

25. Acids/Bases • As water moves around, it is likely that the polarity will cause some hydrogen molecules to come apart from the water molecule (forming hydrogen ions & hydroxide ions) • Basically, H20  H+ + OH- • The free hydrogen ions can associate with other water molecules to form hydronium ions (H3O+)

26. Acids/Bases • Acidity and alkalinity are related to the measure of the hydroxide and hydronium ions in the solution • Equal OH- & H3O+ = neutral solution • More OH- than H3O+ = basic solution • More H3O+ than OH- = acidic solution

27. Acids/Bases • pH – potential of hydrogen • Measure of the acidity & alkalinity • 0-14 scale (0 being most acidic, 7 neutral, 14 being most basic) • Our body is constantly carrying out reactions that form acids, water is constantly moving around. • Our body is extremely sensitive to pH changes. • Your blood ph is 7.35 -7.45. • Most of our enzymes require a pH in that range to function.