Molecules

1
Molecules More

• Unit 3 Lecture 2

2
Discuss

• Put the 9 levels of organization in order from
  smallest atom to largest organism

3
Levels of Organization review

• Atom
• Molecule
• Biomolecule
• aka macro-molecule
• Organelle

• Cell
• Tissue
• Organ
• Organ system
• Organism

4
Molecules

• Molecule composed of two or more atoms
• can be made of a single element
• or multiple elements
• has no overall charge
• example H2 two atoms of hydrogen
• write this in covalent bonding

5
Molecules contd

• Compound a molecule made of two or more
  elements
• my abbreviation cmpd(s)
• MUST have more than one element present
• Ex H2O 2 atoms of hydrogen, 1 atom of oxygen
• ionic compounds have a positive or negative
  charge
• Ex NH4
• write this in ionic or covalent bonding

6
Discuss

• What are the TWO major differences between a
  molecule and a compound?

7
Molecules contd

• Types of Bonds
• Covalent Bonds
• formed when atoms share valence electrons
• co together
• valence electron electron in the outermost
• shell of an atom
• a strong bond
• Ex H2O

8
Molecules contd

• Types of Bonds
• Ionic Bonds
• formed when atoms gain or lose electrons
• by transfer
• weaker than a covalent bond
• Ex NaCl

9
Discuss

• What is the major difference between a covalent
  bond and an ionic bond?hint it has to do with
  the electrons

10
Properties of Water

• Approximately 2/3 of your body is waterso
  apparently its quite important
• What makes water so important??

11
Water is a Polar Molecule

• Polar Molecule has no overall charge hence
  molecule but has a side that is more
  electronegative
• electronegativity the ability of an atom to
  attract electrons to itself
• uneven distribution of electrons leads to a
  negative pull on one side

12
Water is a Polar Molecule

• The oxygen side of the molecule is much more
  electronegative than the hydrogen side

13
Water is a Polar Molecule

• It is the Universal Solvent
• water given this term because it is able to
  dissolve many substances
• this is because of its polarity
• solvent a substance that is used to dissolve a
  solute.
• solute a substance that is dissolved by the
  solvent
• Ex water solvent dissolves sugar solute

14
Water is a Polar Molecule

• Polar is aka Hydrophilic
• hydrophilic literally, water-loving
• hydro water
• philos / phil / philia to love
• dissolve easily in water like sugar
• hydrophobic literally, water- fearing
• phobia / phobic / phobos to fear
• aka non-polar
• do not dissolve or mix easily in water like
  lipids

15
Discuss

• Explain the difference between
• solute solvent
• hydrophilic hydrophobic

16
Water Performs H-Bonding

• Hydrogen Bond bond formed between a H and a
  more electronegative atom
• is very weak
• is not a true bond but
• an attraction
• usually takes place between
• oxygen O, nitrogen N,
• or fluorine F

17
Water Performs H-Bonding

• Adhesion the ability of water to form H-bonds
  with other molecules to stick to other things
  
• think adhesive
• ex straw in water
• water climbs above the surface level
• aka capillary action
• major way blood flows through the capillaries in
  your body and through the roots of plants.

18
Water Performs H-Bonding

• Cohesion the ability of water to form H-bonds
  with other water molecules
• causes surface tension
• Ex water drops form small spheres, can overfill
  a glass, some bugs can walk on water

19
Water Expands when Freezing

• is less dense when frozen
• most substances are more dense
• allows it to float on water when frozen
• if ice sunk, lakes ponds would freeze solid in
  winter

20
Water has a High Specific Heat

• Specific Heat amount of energy it takes for the
  temperature of a substance to increase or
  decrease
• makes homeostasis MUCH easier

21
Discuss

• What four properties of water make it very
  important to living things? answers below
• polar molecule universal solvent
• high specific heat
• hydrogen bonding
• expands when frozen

22
Mixtures

• Mixture a combination of multiple substances
  that
• can be physically separated
• are not combined chemically
• can be homogenous or heterogeneous

23
Mixtures contd

• Mixtures can be homogenous or heterogeneous
• homogenous appearance and consistency are the
  same throughout
• genous type
• typically called solutions
• heterogeneous appearance consistency are
  different throughout
• Ex ?

24
Mixtures contd

• Solution a mixture that
• is homogenous
• is in a single phase
• solid, liquid, or gas
• can have different phases dissolved in one
  another
• gas in liquid carbonated water
• solid in solid alloys carbon/iron steel
  copper/zinc brass
• solid in liquid sugar water
• etc.

25
Mixtures contd

• Solution a mixture that
• uses the term solute solvent
• solubility the ability of a substance to
  dissolve in another

26
Discuss

• Explain the difference between homogenous and
  heterogeneous mixtures.
• Which type of mixture is a solution?

27
Homework

• Complete the first side of the Osmosis
  Diffusion w/s
• Finish the organelles worksheet will be
  collected tomorrow.