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

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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

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slide1

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.
slide2

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?

slide3

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?

slide4

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!

slide9

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
slide10

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

slide12

What elements are most common in living things?

Abundance of Elements in the Universe cartogram

Abundance of Elements on Earth cartogram

slide13

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.

slide14

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.

slide15

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

slide16

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!

slide17

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.

slide19

What does the prefix “hydro” mean?

What is a phobia?

What is a pedophile?

slide20

Hydro = “water”

Like in hydroelectric dam

phobia = “does not like”

Like in arachnophobia

phile = “attracted to”Like in audiophile

slide21

Hydrophobic = doesn’t like with water (it won’t mix with water).

  • Nonpolar
  • Hydrophilic = attracted to water (it will mix with water).
  • Polar
slide22

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…

slide24

So, do you think…

If something is polar, is it always hydrophilic?

If something is nonpolar, is it always hydrophobic?

YES(pretty much)

slide25

Properties of Water

  • Cohesion: Water is attracted to itself.
  • It makes hydrogen bonds!
slide26

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.

slide28

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!

slide29

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.

slide30

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.

slide31

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.

slide34

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?

slide35

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.
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