True or false: polar molecules share their electrons equally between atoms.

1. 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.

2. 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?

3. 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?

4. 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!

6. Topic 2: Molecular biology (21 hours)

7. 2.2 Water

8. What are some things you remember about atoms?

9. 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 n0and p+ (depending on the isotope) Atomic Symbol • 1 or 2 letter abbreviation Element Name • There are many element names; xenon is the best name

10. 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

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

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

13. 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.

14. 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.

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

16. 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!

17. 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.

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

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

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

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

22. 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…

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

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

26. 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.

27. What is the “lake effect”?

28. 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!

29. 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.

30. 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.

31. 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.

33. In your notebook, make this table and fill it in:

34. 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?

35. 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 printedand turned in) • Get a library pass to print it, or to work on it anytime between now and Monday.