Biology Journal 8/27/2014 2.2 Homework Quiz! True or false: polar molecules share their electrons equally between atoms. In water molecules, which atoms display a slight negative charge? Hydrogen Oxygen The attraction between the hydrogen atom of one water molecule and the oxygen atom of another water molecule is called…. An ionic bond A polar covalent bond A hydrogen bond Love Water tends to stick to other substances. What is this property called? Water and oil repel each other. That’s because oil is an example of a ______ substance.

Why do you think the pepper was “afraid” of the soap? Biology Journal 8/28/2014 Which substance were you able to fit the most drops of liquid on top of a penny? What do you think could be some reasons for that? Why do you think the pepper was “afraid” of the soap?

Where do we find hydrogen bonds between water molecules? Biology Journal 9/2/2014 What is a hydrogen bond? Where do we find hydrogen bonds between water molecules? Where do we find hydrogen bonds in DNA?

Hydrogen bonds form between polar molecules. (+) side attracted to (-) side a weak bond (it is easily broken) The fact that water is polar, and forms hydrogen bonds explains it’s important properties to living things!

Topic 2: Molecular biology (21 hours) 2.2 Water: Water is the medium (means of doing something) of life. Nature of science: Use theories to explain natural phenomena—the theory that hydrogen bonds form between water molecules explains the properties of water. Understandings: Water molecules are polar and hydrogen bonds form between them. Hydrogen bonding and dipolarity explain the cohesive, adhesive, thermal and solvent properties of water. Substances can be hydrophilic or hydrophobic. Applications and skills: Application: Comparison of the thermal properties of water with those of methane (to understand the significance of hydrogen bonding). Probes can be used to determine the effect of different factors likely to influence cooling with water. Application: Use of water as a coolant in sweat. Application: Modes of transport of glucose, amino acids, cholesterol, fats, oxygen and sodium chloride in blood in relation to their solubility in water. International-mindedness: There are challenges for the increasing human population in sharing water resources equitably for drinking and irrigation, electricity generation and a range of industrial and domestic processes.   Theory of knowledge: Claims about the “memory of water” have been categorized as pseudoscientific. What are the criteria that can be used to distinguish scientific claims from pseudoscientific claims?

2.2 Water

What are some things you remember about atoms?

What are these things called? What do they tell you? Atomic Number Atomic Mass Number of p+ Number of e- Average mass of all isotopes Number of n0 and p+ (depending on the isotope) Atomic Symbol 1 or 2 letter abbreviation Element Name There are many element names; xenon is the best name

What is this part called? What do you know about it? Electron Proton Negative charge Can be gained, lost, or shared to form chemical bonds Positive charge Determines the element Orbitals Neutron Determines if an element will gain, lose, or share a specific number of electrons Nutreal charge Can be different numbers (isotopes) What element is this? Nitrogen

The periodic table of elements tells you a lot about what’s in an atom.

What elements are most common in living things? Abundance of Elements in the Universe cartogram Abundance of Elements on Earth cartogram

What are some things you remember about ions? Ions are atoms that have gained or lost electrons. This gives them a (+) or (–) charge. Ionic substances are solids, but most easily dissolve in H2O.

What do you know about covalent bonds? Electrons can be shared evenly (nonpolar) or unevenly (polar) A covalent bond forms when atoms share their extra valence electrons.

Polar molecules (AKA dipolar) do not share electrons evenly, giving it a positive (+) side and a negative (-) side. Water is very polar!

Hydrogen bonds form between polar molecules. (+) side attracted to (-) side a weak bond (it is easily broken) The fact that water is polar, and forms hydrogen bonds explains it’s important properties to living things!

So, whenever you take a drink of water, just imagine those little Mickey mouse heads vibrating and bouncing off of each other, making and breaking hydrogen bonds, and interacting with other molecules that they come into contact with.

Lipids are nonpolar molecules. They don’t have a charge on one side. a saturated fatty acid

What does the prefix “hydro” mean? What is a phobia? What is a pedophile?

Hydro = “water” Like in hydroelectric dam phobia = “does not like” Like in arachnophobia phile = “attracted to” Like in audiophile

Hydrophobic = doesn’t like with water (it won’t mix with water). Nonpolar Hydrophilic = attracted to water (it will mix with water). Polar

Rules of Attraction Polar molecules Attracted to polar Repel nonpolar Nonpolar molecules Attracted to nonpolar Repel polar Molecules are attracted to other molecules that are similar to them. Aww, just like people…

YES(pretty much) So, do you think… If something is polar, is it always hydrophilic? If something is nonpolar, is it always hydrophobic? YES(pretty much)

Cohesion: Water is attracted to itself. It makes hydrogen bonds! Properties of Water Cohesion: Water is attracted to itself. It makes hydrogen bonds!

Adhesion: Water is attracted to other substances. Properties of Water Adhesion: Water is attracted to other substances. Water’s attraction to other substances is important in ground water, and how plants suck up that water! Water is adhesive! It sticks to things like a shirt.

What is the “lake effect”?

Properties of Water High Specific Heat: It takes a lot of energy to change water’s temperature. Technically, specific heat is the energy required to heat 1 kg of a substance 1°C Most metals have a low specific heat. It will heat up fast and cool down fast!

Properties of Water Heat of evaporation: When water evaporates, this consumes a lot of heat. Water’s high heat of evaporation of water related to water’s high specific heat. Hydrogen bonds attract water molecules to eachother, so they resist changing temperature or phase.

Properties of Water Surface Tension: Energy is required to overcome the cohesion of water, and pass through the surface. The surface tension of water is kind of like a game of Red Rover.

Good Solvent: Water can dissolve many kind of substances. Properties of Water Good Solvent: Water can dissolve many kind of substances. Things like lake water, ocean water, and blood can dissolve a huge amount of nutrients.

In your notebook, make this table and fill it in: Property of Water How does the magnetic model show this property? How could this property be beneficial to organisms in real life? Hydrogen bonding Hydrophilic Surface Tension Cohesion Adhesion Good solvent High Specific Heat Heat of Evaporation

What are some ways that H2O’s specific heat help out living things? Biology Journal 9/4/2014 What could be an example of something that has a high specific heat? A low specific heat? What are some ways that H2O’s specific heat help out living things?

No Journal today. Read these reminders, then get right to work on your mini-posters. When you get a laptop, keep the charger on the shelf it was on. When done, put your labtop back on the correct shelf and charge it! It’s due Monday! (it must be printed and turned in) Get a library pass to print it, or to work on it anytime between now and Monday.