Water and Life; The scientific method; pH, acids and bases 

Key Terms:

• Polar molecule -  A neutral, or uncharged molecule that has an asymmetric internal distribution of charge, leading to partially positive and partially negative regions 

• Cohesion - The attraction of molecules for other molecules of the same kind 

• Adhesion - The attraction of molecules for other molecules of a different kind 

• Density - The mass per unit volume of a substance 

• Specific heat capacity - The amount of heat needed to raise the temperature of one gram of a substance by one degree Celsius 

• Heat of vaporization - The amount of energy needed to change one gram of a liquid substance to a gas at constant temperature 

Properties of water: 

• Water is polar 

• Water is a solvent 

• Water has high heat capacity 

• Water has high heat of vaporization 

• Water has cohesive and adhesive properties  

• Water is less dense as a solid than a liquid

Key Terms:

1. Biology - The study of living things

2. Observation - Noticing and describing events in an orderly way 

3. Hypothesis - A scientific explanation that can be tested through experimentation or observation

4. Controlled Experiment - An experiment in which only one variable is changed 

5. Independent variable - The variable that is deliberately changed in an experiment 

6. Dependent variable - The variable that is observed and changes in response to the independent variable 

7. Control group - Baseline group the does not have changes in the independent variable

8. Scientific theory - A well-tested and widely accepted explanation for an occurrence

9. Placebo - A substance that has no therapeutic effect, often used as a control in experiments 

10. Double blind study- Study in which neither the participants nor the researchers know who is receiving a particular treatment

(In order for something to be considered living, it must meet all of the properties below) 

Properties of Life: 

• Organization 

• Metabolism

• Homeostasis

• Growth

• Reproduction

• Response

• Evolution

Some ways to avoid errors and bias experiments: 

1. Having a large sample size in an experiment 

2. Repeating experimental trials multiple times 

3. Including all data points

4. Using placebos, when appropriate 

5. Implementing double blind studies

Key Terms: 

• pH - The measure of the Hydrogen ion (H+) concentration in a solution 

• Acid - Solution with a higher concentration of hydrogen ions than pure water 

• Base - Solution with a lower concentration of hydrogen ions than pure water 

Reading the pH scale:

• The pH scale is used to rank solutions in terms of how acidic or how basic they are. It indicates the concentration of hydrogen ions (H+) and hydroxide ions (OH-) in a solution. These ion concentrations are equal in pure water, which has a pH of 7.

• This pH value of 7 is important because it indicates a neutral solution. All other substances are compared to this neutral point. Any solution that has a pH of less than 7 is considered acidic, and anything above a pH of 7 is basic.

Something to keep in mind:

• Acids are not always dangerous. Orange juice is acidic, but healthy. 

• If the pH is less than 7 then it's considered acidic and if it’s higher than 7 then it’s considered basic.