2. Chapter 2 The Chemistry of Life Section 1 – Nature of Matter

3. Atoms What is matter made of? 1. Atoms &Definition – Basic Unit of matter In normal terms – smallest pieces of any material

4. 2. Elements &Definition – Substance consisting of 1 type of atom In Normal terms – pure substances (many atoms of the same type) Oxygen,, Copper, anything on the periodic table

5. 3. Isotopes Definition – An Element that has a number of neutrons different from other atoms. In Normal terms – An atom with too many neutrons. (Makes it radioactive)

6. Chemical Bonding What holds all of this matter together? 3 Types of Chemical Bonds

7. 1. Ionic Bonds Definition- when electrons are transferred from one atom to another. What is that like? An unequal relationship, where one person takes something from another, but does not give anything back.

8. How Strong are they? Not very strong. They are weak enough that they dissolve in water (i.e., salt) See the example of how salt forms on the next page.

9. Chlorine takes an electron from Sodium That creates a weak bond that forms salt. Sodium Chlorine

10. 2. Covalent Bond Definition- Where two atoms share electrons What is that like? A mutual relationship where both people give and take.

11. How Strong are they? Very Strong. Does not dissolve in water (i.e., sugar) – Most of your body is made of covalent bonds … you know this because you do not melt. (living things are made of covalent bonds)

12. Examples of Covalent bonds Hydrochloric Acid Water Hydrogen Gas

13. . Hydrogen Bonds  Definition- The slight attraction of oppositely charged ends of nearby molecules What is that like? The attraction between two magnets. They don’t need to be touching, just close.

14. How Strong are they? Very weak – only works if the two atoms are really close to one another and not moving around.

15. Hydrogen bonds hold water molecules together. That stabilizes the molecules enough to form surface tension. You can see that surface tension holding up this water strider. It is almost like the water has hardened like a sheet of plastic wrap.

16. Section 2 – Properties of Water Water in Living Things Properties of Water  1. Water molecules are polar (uneven charges) Why is that important? It is what allows Hydrogen bonds to form. No polarity and the water strider sinks.

17. 2. Cohesion and Adhesion Cohesion Definition- Water is attracted to itself (causes surface tension & holds water together while it flows) Adhesion Definition- Water is attracted to other polar molecules (Allows water to carry most of the chemicals you need to live) What causes these attractions? The uneven charges that cause hydrogen bonds.

18. Aqueous Solutions 1. Solution  Definition The solute evenly dissolves in the water Powdered Iced tea mix in water is clear. The powder is completely dissolved.

19. 2. Suspension  Definition The solute never dissolves Like the soil in the floodwaters that devastated New Orleans. As it settled out, it left the undissolved solute behind as mud.

20. Acids and Bases 1. The pH Scale  What molecule creates the ions that affect pH? water  Name the two resulting ions – Hydrogen (H+) and Hydroxide (OH-)  What range of numbers are used to represent pH? 1-14

21. Acid 1. What makes something an Acid? If it has more H+ than OH- when it is dissolved in water  What pH numbers represent acids? 1-7 ( 1 is the most acidic you can get)

22. 1. Name some acidic things? (enter items from the scale below) What do they all have in common? They all taste sour They are common in living things.

23. Base 1. What makes something a base (aka alkaline)? More OH- than H+ when it is dissolved in water.  What pH numbers represent bases? 7-14 (14 is the basic)

24. 1. 1. Name some basic things? (From the chart) What do they all have in common? They all taste bitter They are extremely rare in living things. Almost always poisonous. Tums / Rolaids Draino

25. Neutral 1. What makes something a neutral? An equal amount of H+ and OH- 2. Name one neutral thing? Water 3. What number represents a neutral? 7  7.Where does human blood fit into this scale? 7.4