Bio.A.1.2.2: Describe the unique properties of water and how these properties support life on Earth Objective: What makes water so important and unique? Warmup: ***Brainstorm*** What properties do you remember about water? (ex. Freezing point, density, chemical formula, etc) Anything that you can remember…..

Bio.A.1.2.2: Describe the unique properties of water and how these properties support life on Earth Objective: What makes water so important and unique? Warmup: ***Brainstorm*** What properties do you remember about water? (ex. Freezing point, density, chemical formula, etc) Anything that you can remember….. Period 1

1. If you don’t live in it, you carry it with you: water makes up 60-95% of most organisms. 2. It plays many roles in the body: Allows molecules & ions to move, collide and dissolve Decreases concentration in blood for easier movement/better pH levels Allows chemical reactions to occur Maintains a constant body temperature (homeostasis)

1. Water is polar (exhibits polarity) Polar molecule – molecule with an unequal distribution of charge; each molecule has a negative (-) and positive (+) end.

1. Water is polar (exhibits polarity) Shape (^) of water indicates oxygen attracts more e- than hydrogen; oxygen acts (-) and hydrogen acts (+) Water’s overall charge = 10 p+ 10 e- zero Polar molecules are very attractive because (+) and (-) ends function like a magnet

1. Water is polar (exhibits polarity) - Because water is like a magnet: They (water molecules) attract: ions example: sodium (Na+) and chloride (Cl-) polar molecules example: sugar (carbohydrate) water

2. Water forms hydrogen bonds (bond between +/- ends of a polar molecule) Characteristics:  Weak bond – formed/broken easily

 Part 1:  Draw a model of one water molecule.  1.) Show the number of protons, neutrons and electrons in the shells of the atoms involved.

 Part 2:  Cut out a model of one water molecule.  1.) Color the oxygen atoms of each water molecule red.  2.) Color hydrogen blue  3.) Indicate the relative charge of each side of the water molecule by placing a plus or a minus on the correct sides.

Bio.A.1.2.2: Describe the unique properties of water and how these properties support life on Earth Objective: What makes water so important and unique? Warmup: What does it mean when we say that water is POLAR? Draw a picture or explain it please.

 On your cut-outs page:  1.) Color the oxygen atoms of each water molecule red.  2.) Color hydrogen atoms blue.  3.) Indicate the relative charge of each side of the water molecule by placing a plus or a minus on the correct sides.  4.) Cut out 5 molecules.  5.) Arrange them to show hydrogen bonds. Indicate the hydrogen bonds between each water molecule by drawing three black dots between them.

2. Water forms hydrogen bonds (bond between +/- ends of a polar molecule) Characteristics:  Weak bond – formed/broken easily  Responsible for cohesion – intermolecular attraction between like molecules (example: H 2 O - H 2 O)  Produces surface tension so insects, leaves can float on water  Water molecules stick together to move against gravity (capillary action)

2. Water forms hydrogen bonds (bond between +/- ends of a polar molecule)  Hold large molecules and H 2 O together. Adhesion – the intermolecular attraction of unlike molecules  Water forms droplets on leaves  Water molecules stick together to move against gravity (capillary action)

Like molecules Unlike molecules Water is “sticky”!

1. Has less density as a solid Water forms crystal-like bonds when it freezes, keeping the molecules at fixed distances from each other Low density – less tightly packed Water expands when frozen and floats, allowing organisms to live underneath

2. Is a universal solvent Dissolves many compounds such as carbohydrates and some proteins Allows chemical reactions to occur

3. Has high heat of vaporization Amount of heat energy needed to change 1 g of 100˚C boiling water to 100˚C steam (you sweat and water evaporates off your skin to cool you)

4. Has high specific heat Amount of energy required to change 1 gram of water by 1˚C (water resists change in temperature) Substances with H-bonds take longer to cool or heat than those w/o Allows organisms to maintain a stable internal environment (homeostasis) Allows water to resist temperature change

 Water is known as the Universal Solvent:  Solutions have 2 parts:  Solute – what is being dissolved  Solvent – what is doing the dissolving

NaCl Solution and dissolving

 pH Scale – Measures the amount of hydrogen ions in a solution  Low