1. Chemistry of Life Chapter 2

2. Warm Up 8/27 Draw a Boron atom. Draw a Potassium Ion Draw Magnesium Sulfide Ionic Bond Draw H2O (covalent bond)

3. Properties of Water When scienctists look for evidence of life on other planets, they search for water. Why is water so important to life? It is the medium in which chemical reactions take place. Water gives cells structure. Polar molecules—? Example: Water molecule with slightly positive Hydrogen and slightly negative Oxygen. They are joined by hydrogen bonds

4. Hydrogen Bonds Hydrogen Bond-attraction between a slightly positive hydrogen atom and a slightly negative atom, often oxygen or nitrogen. (See drawing) Properties Related to Hydrogen Bonds High Specific Heat-Hydrogen bonds give water a high specific heat. Water absorbs heat, which helps to regulate cell temperatures Cohesion-this makes water molecules stick together (ex. Water forms a bead)-2 same Adhesion-like tape holding together 2 things.

5. Properties of Water Continued. Many compounds dissolve in water. Important materials like sugars and oxygen can’t be transported through organism unless they are dissolved. Solution-a mixture of 2 different substances Solvent- substance that dissolves another substance Solute- substance that dissolves in a solvent.

6. Acids, Bases, and pH Some compounds break into ions when they dissolve in water. Acids- compound that releases a proton-H+ ion when it dissolves in water=high H+ concentration =low pH-1-6 Bases- compounds that remove H+ ions from a solution=low H+ concentration = high pH=7=14 pH- measurement of a solution’s acidity or H+ ion concentration