1. What’s Important About the Nutrition Label?
What does the label tell you?
Why is this important?

2. Unit 3:The Chemistry of Life
Unit Objective:
To identify the carbon-based organic molecules of life and understand the roles they play in life processes.
Lesson Objective:
To know how an atom is constructed and how each element’s properties determines how the formation of compounds (bonding) takes place.
Only copy down underlined material.
Everything else is there for support.

3. First Question… Why do we study CHEMISTRY in BIOLOGY class…
So. Why do we?...

4. What Are Organisms Made Of?
Every organism is different depending upon it’s role or needs but there are basic elements that are universal to life on Earth.

5. The Basic Compounds of Life.
Regardless of the amount, most organisms use elements to form these Macromolecules of Life.
Fats
Proteins
Sugars
Nucleic Acids.
These are the fundamental molecules of life that you will be required to know.
These carbon-based molecules are known as Organic Compounds.
Another molecule you will learn about in this mini-unit is water.

6. Essential Questions Objectives
How does hydrogen, carbon, and oxygen combine to form molecules that participate in living systems?
What do these molecules do to support life?
Objectives
To review/identify what makes up matter.
To know the elements that form most organic molecules.
To review/understand why atoms form bonds.
To understand how and why these bonds are essential for life by forming the carbon-based organic molecules of life.
This information will help you soon be able to explain how these molecules participate in important processes in living things.

7. 1st Step
Get into groups.
Use your resources to fill in the blanks and answer the questions.
Tomorrow we’ll discuss and get any questions answered.

8. Vocabulary
Atoms
Element
Valence electrons
Compound
Molecule
Ion

9. Before You Learn About the Organic Macromolecules…
You must understand that all bigger molecules are built of smaller pieces.
Everything of atoms…
Sometimes arranged into basic molecules.
These smaller pieces are called…
These will sometimes be called… (a.k.a.)
What is a subunit?
Something that is combined with other subunits to build something bigger.
SUBUNITS
BUILDING BLOCKS or MONOMERS

10. Atoms Every living and nonliving thing is made of matter.
Matter is anything that has mass and takes up space.
All matter is made of very small particles called atoms.
An atom is the smallest unit of matter that cannot be broken down by chemical means.

11. Atoms
The atom is composed of three main types of smaller “subatomic” particles.
Protons: positively charged particles.
Neutrons: particles with no charge.
Electrons: negatively charged particles.

12. Atoms The particles are in two specific areas:
The nucleus.
The electron cloud.
Protons and neutrons are in the nucleus.
Electrons are in various energy levels contained in the electron cloud around the nucleus.

13. What are the parts of an atom?B C A D

14. How Is an Atom Built? Every box represents a different element.
Find carbon on the periodic table.
This is the information for the element CARBON
Notice its row and column.
Every box represents a different element.
An element is any quantity of a substance that is 100% the same type of atom.
Being the same type means they have the same # of protons.
Ex: Diamonds are always the element carbon, regardless of the size, because every atom has 6 protons.

15. CHNOPS: What are the Most Abundant Elements in Biology?
The six highlighted below are the most abundant elements in the bodies of most biological organisms.
Take out the periodic tables & Mark these in your Periodic Table.

16. Reading the Periodic Table
Atomic Number
Symbol
Name
Atomic Mass

17. Atomic Numbers, Mass, Electrons…
The boxes give a lot of information.
How do you know how many protons, electrons, and neutrons an element has?
It’s all based upon the atomic number found in the periodic table.
Atomic # = # protons
# electrons = # protons
# neutrons = atomic mass - # protons.

18. What Happens When an Atom Gains or loses an Electron is Ionic.
Usually, atoms by themselves if stable will have equal numbers of protons & electrons.
If this is the case the charges cancel and they are neutral.
If an atom gains or loses electrons they become ions.
Ions are atoms that have a charge because the proton-electron numbers don’t match.
Ions are formed by electrons ‘jumping’ from one atom to another.

19. Formation of Ions: Count the p+ & e- before & after the exchange…
Cation:
A positively charged ion.
Anion:
A negatively charged ion. Na + Cl -
Sodium
Before
After
Chlorine
Protons
+11
+17
Electrons
-11
-10
-17
-18
Total +1 -1

20. Special Circumstance: Isotopes
Elements
Recall, elements are all the same type of atom because every atom has the same number of protons.
For example, every atom for any amount of the element carbon has six protons.
There are several types of carbon though.
Atoms of an element can have different numbers of neutrons.
Isotopes are atoms of elements that have a different number of neutrons.
Isotopes create challenges and benefits because bonds form differently and are usually radioactive to a degree.

21. Isotopes
Because Isotope atoms have the same number of protons, and also electrons, isotopes have the same chemical properties.
However, isotopes are unstable and release radiation as they decay (shed the extra neutrons)
Some radiation is worse than others.

22. The Numbers Really Matter
The numbers represent an atom’s proton, neutron, and electron number when it is un-bounded and electrically neutral.
Atoms are rarely like this, stable, in nature.
Mainly because the electrons are always flying around.
electron

23. The Energy Levels
Atoms are usually represented as a nucleus surrounded by rings.
The rings are energy levels.
The rings exist because e- can’t occupy random or the same space at the same time.
There are rules to how the e- are distributed.
The row (going from top to bottom) tells you how many rings the atom has.
Hydrogen is in the 1st row = one ring
Nitrogen is in the 2nd row = two rings
Shown to the right.
How many rings does iodine have?
These are the atom’s energy levels.

24. Reading the Periodic Table
The Column tells you how many electrons in the outer shell (valence electrons).
The Row tells you how many rings (Energy levels)

25. The Outer Ring… The Valence Shell
Remember, electrons are orbiting the nucleus in the region called the electron cloud... In different energy levels (orbitals).
The outer ring, called the valence shell, is the important one.
This shows you the valence shell electrons.
In the valence shell bonding happens.

26. The Outer Ring
The outer most edges of this cloud is called the valence shell.
There is a strict rule for how many electrons are in this valence shell.
For most groups of atoms, you can determine the # of valence shell electrons from the column it’s in.
The column determines the valence shell electrons.
Group 1A (hydrogen, etc.) has one valence electron.
Group 2A (beryllium, etc.) has two.
This rule only applies to A groups though.
How many valence electrons does phosphorus have?
A: 5

27. Concept Check
On your handouts (back side of the periodic table), complete the blank atom for the element carbon.
Draw the:
Correct # of electrons
Correct # of electron in the valence shell
Correct # of protons
Correct # of neutrons
Put them in the correct places.

29. Representing the Atom
Lots of Atom Models
Which one’s right?
Depends on the application

30. How do you show bonds?… Lewis Dot Structures are best
Shows only symbol & the valence e- that participate
in bonding.

31. Bohr’s V. Rutherford’s - - - - - - + + + + + + - - + + - + + + + - - -
Same Orbit
Different Orbits

32. Where electrons actually are…Schrödinger
Q: Can you identify where the electron is? +
A: No! because the electrons never stop moving!

33. Representing the Atom Bohr’s Diagram Lewis Structure
Shows the nucleus, all energy levels, and electron distribution.
Lewis Structure
Shows the atomic symbol & valence e-.
Shows the nucleus (with p+ & n0) plus all inner energy levels (& electrons) represented by the atomic symbol.
Usually the easiest one to use.

34. Practice. Create the Bohr & Lewis Structure for…
Oxygen
Sodium
Chlorine
Uranium

35. CW/HW Answers
Oxygen
Sodium
Chlorine
Tellurium

36. CW/HW Answers
Oxygen
Sodium
Chlorine
Uranium
Sorry, bad example

37. Chemical Bonds
Electrons in the valence shell are called valence electrons.
The number 8 is special.
This determines what atoms will bond with what.
Write this just above IX. Chemical Bonds
*OCTET RULE* (Generally speaking) Atoms tend to combine with each other such that eight electrons will be in the valence shell.
The reason is stability!
Regardless of the reason, when atoms are held together a force called a chemical bond holds them.
There are three types of bonds that you need to know.
Ionic bonds
Covalent bonds
Hydrogen bonds.

38. Types There is an order of strength…
There are three types of bonds that you need to know.
Ionic bonds = When atoms SWAP electrons creating ions that attract.
Covalent bonds = When atoms SHARE electrons to create molecules.
Hydrogen bonds = When polar molecules interact with one another.
There is an order of strength…
Covalent > Ionic > Hydrogen. (covalent is the strongest)

39. Valence electrons: Do the Bonding

40. Special Circumstance: Noble Gasses
Some atoms won’t bond with other elements because they already have 8 valence electrons.
These are called Nobel Gasses.
These are group 8A (all the way on the right).

41. Chemical Bonds
Every other element will bond with other elements to get to 8 valence electrons.
Chemical bonds form between groups of atoms because atoms become stable when they have eight electrons in the valence shell.
When atoms of different elements combine, a compound forms.
A compound is a substance made of the bonded atoms of two or more elements.

42. Common Compounds Ammonia (NH3) Water (H2O) Methane (CH4)
Glucose (C6H12O6)
Salt (NaCl)

43. Ionic Compounds Ionic Bonding
Atoms can sometimes achieve a stable valence level by losing or gaining electrons.
When this happens, the charge of the atom changes slightly and an ion is formed.
[An ion is an atom or group of atoms that has an electric charge because it has gained or lost electrons.]
Opposite charges attract.
The attractive force between oppositely charged ions is an ionic bond.

44. How Do You Know How Many Electrons Get Exchanged?
It is all based upon the number of valence electrons for the element in its basic form.
The metals on the left usually give electrons because they are closer to 8 if they lose a few.
The non-metals on the right usually gain electrons because they will achieve 8 if they gain just a few.

45. Find These Elements on you Periodic Table
Gains e-
Carbon
Gains or
Loses e-
Loses e-
How close are these elements to achieving 8 in their valence shell?
Is it faster to gain a few or lose a few?
The numbers of e- gained/lost are variable & correspond to how many they need.
What about carbon?

46. Complete B1 from handout
Complete B1 from handout. Formation of Ions: Count the p+ & e- before & after the exchange… Na + Cl -
Sodium
Before
After
Chlorine
Protons
+11
+17
Electrons
-11
-10
-17
-18
Total +1 -1

47. How Do You Show the Bonds?
Ionic
Bohr Model
Or…
Lewis Structure
We use Lewis Structures which only show the valence electrons.

48. Show the bonding of Na with Chlorine
Figure out how many electrons sodium loses.
How many does chlorine need?
Find these and fill these out on your sheet.
-1 for sodiums
+1 for chlorine
Draw the arrow showing the electron moving.
Lewis Structure

49. Example: MgI2 I +2 -1 -1
WHY?

50. Since each chlorine received one electron what should each charge be?
Magnesium chloride. (Just like B2): Since Magnesium donated 2 electrons what should its charge be? Cl +2 -1 -1
When Magnesium loses its outer electrons it exposes its next lower energy level, which happens to have 8 electrons.

51. Chemical Bonds, continued
Covalent Bonding
One way that atoms bond is by sharing valence electrons to form a covalent bond.
A molecule is a group of atoms held together by covalent bonds.
A water molecule, H2O, forms when an oxygen atom forms covalent bonds with two hydrogen atoms.

52. Poor Oxygen… Ah, I’m sad because my valence shell isn’t filled.
If there was only some way to get more.
Wait. Hey Buddy. If we shared some electrons, then we could both have 8…kinda.
Now we both can have eight!
Sometimes… and that’s enough to form a covalent bond.

53. How Do You Show the Bonds?
Covalent
Bohr Model
Lewis Structure
Or…

54. Illustrate the bonding of 2H + O to make H2O
2 minutes…
How many electrons does oxygen need?
How many does hydrogen need?
How would these be shown in a bond?
Lewis Structure

55. Example: C02

56. Polarity
In some covalent molecules, the electrons are shared equally between the atoms in the molecule.
In some covalent bonds, the shared electrons are attracted more strongly to one atom than to the other.
It’s due to electronegativity (something you don’t need to know.
As a result, one end of the molecule has a partial negative charge, while the opposite end has a partial positive charge.
Polar Molecules result when the resulting molecule has partial charges on opposite ends because of electron motion and average location.
Non polar molecules, like CO2,

57. Same Atoms sharing electrons equally Make it Non-Polar+ - + - - - - - -

58. Not Sharing Electrons Equally Results in Polar Molecules-
Partially –
The electrons spend more time on this side of water. - - - - - -
Partially +
The electrons spend less time on this side of water - - -

59. Not Sharing Electrons Equally can sometimes be 2 atoms, sometimes more.- - - - - -
Partially +
Partially - - -

60. Represented as dashed lines.
Hydrogen Bonding
A hydrogen bond is a bond that forms between the positive hydrogen atom of one molecule and the negative pole of another molecule.
Represented as dashed lines.
We will see these again…

61. Polarity, continued Hydrogen Bonds
When bonded to an oxygen, nitrogen, or fluorine atom, a hydrogen atom has a partial positive charge nearly as great as a proton’s charge.
It attracts the negative pole of other nearby molecules.
This attraction is stronger than attractions between other molecules, but not as strong as covalent bonds.
However, hydrogen bonding plays an important role in many of the molecules that make up living things.

62. Polarity of Water Water is a molecule that shares electrons unequally.δ+
2δ-
Water is a molecule that shares electrons unequally.
Oxygen attracts the electrons more than hydrogen does.
This causes the oxygen atom to be, on average, more negative than the hydrogen, which tend to be more positively charged.

63. Polar Molecules: Water
The polarity of water makes it able to form polar bonds with other water molecules, called hydrogen bonds, due to the negative oxygen and the positive hydrogen. δ+
2δ-

64. Atomic Models There are a variety of ways to represent an atom…
It really depends on why you are showing the atom that will determine how you show it.
Electron-Dot Diagrams = show electrons & protons for ions & bonding
Space filling models = show how the molecule looks in 3D
Bohr’s model = shows all electrons to represent energy levels. WHAT YOU BUILT
Lewis structures = shows valence electrons (only) for bonding

65. Concept Review What are the three subatomic particles?
Where are they located?
Do electrons go anywhere they want?
What is an isotope?
What is an ionic bond?
What is a covalent bond?
What makes a molecule polar?
Which is a Lewis structure & which is a Bohr’s model?

66. Why Bonding is Important?
The reason why we review bonding is because the ability of atoms to interact with each other allows for them to build larger molecules.
Depending on the types of numbers of atoms an almost limitless number of molecules and compounds can be formed, each with its own unique properties.
These build on one another to make life possible.

67. Practice Draw Oxygen Draw Phosphorus
Illustrate the ionic bonding between sodium (Na) & chlorine (Cl)
Draw the electrons (e-) between hydrogen & oxygen in H20
Illustrate the polarity of water & draw the hydrogen bonding between two water molecules.
2 minutes + check each.
Keep in mind, in an ionic bond, electrons leave one atom and travel to the valence shell of another.
Keep in mind, in a covalent bond a pair of electrons are participating in the bond; one from each atom.

68. Group Practice Complete the chart using your periodic table.
10 minutes.

69. How do you show bonds?… We will use Lewis Dot Structures
Shows only symbol & the valence e- that participate
in bonding.

70. Illustrate the ionic bonding. 2 minutes each.
DON’T DO DO DO
DON’T DO

71. Illustrate the covalent binding. 2 minutes each
DON’T DO
DON’T DO DO DO

72. Now Get into your groups.
Together you will use your notes and books to complete the worksheet so I know you understand the basic concepts of bonding.
We will cover the answers with 15 minutes left in class so get busy and stay on task.

73. Closure… Questions? What did you learn today?
Reflect in your warm ups…

74. How to Represent an Atom.
Standard Electron Dot Diagram.
Space-filling (O2)
Bohr’s Model
Lewis Structure

75. Sample Questions: Self Quiz. Answers on the next slide.
A(n) _________ is the smallest unit of matter that cannot be broken down by chemical means.
Identify the 3 sub atomic particles of atoms and their locations in words or in an illustration.
A(n) _________ is a substance made of only one kind of atom that has the same number of protons.
Locate oxygen and tell me how many protons, neutrons, and electrons it has. (use your periodic table…the atomic number is extremely useful).
Atoms are most stable when they have 8 electrons in their ______ ______.
How many protons, electrons, neutrons, energy levels, and valence electrons does carbon have?
Name two ways that atoms can form bonds (combine to become more stable).
Describe polarity and a popular polar molecule.
Explain how polarity can cause salt & sugar to dissolve in water.
Water is an example of a compound that is held together by ________ bonds.
Atoms gain or lose ___________ to form ions.
The opposite ends of a polar molecule have ___________ charges.
A(n) _______ ______ is a weak chemical attraction between polar molecules.

76. Answers
A(n) _________ is the smallest unit of matter that cannot be broken down by chemical means.
Identify the 3 sub atomic particles of atoms and their locations in words or in an illustration.
A(n) _________ is a substance made of only one kind of atom that has the same number of protons.
Locate oxygen and tell me how many protons, neutrons, and electrons it has. (use your periodic table…the atomic number is extremely useful).
Atoms are most stable when they have 8 electrons in their __________ _________.
How many protons, electrons, neutrons, energy levels, and valence electrons does carbon have?
Name two ways that atoms can form bonds (combine to become more stable).
Describe polarity and a popular polar molecule.
Explain how polarity can cause salt & sugar to dissolve in water.
Water is an example of a compound that is held together by ___________ bonds.
Atoms gain or lose _______________ to form ions.
The opposite ends of a polar molecule have ___________ charges.
A(n) __________ _________ is a weak chemical attraction between polar molecules.
atom
p+, e-, n0… p+, n0 in nucleus, e- in electron cloud
element
valence
shell
Ionic (swapping electrons), covalent (sharing electrons)
When a molecule has a partial + & partial – charge. Water is polar and can dissolve the ions & polar molecules in sugar & salt because of polarity.
covalent
electrons
opposite
hydrogen
bond

77. Quick Facts. Put an atom into perspective.
If you used a stadium to model and atom…
The Houston Astrodome (Home of the Houston Astros…a baseball team) seats 60,000 fans, covers 9 acres and the dome rises to a height of 200ft.
If you could blow up an atom to the size of this stadium a basketball could represent the volume of an atom's nucleus.
The rest of the open area is the volume of where the electrons, maybe the size of tiny BB’s, would be constantly flying around at speeds approaching the speed of light through the electron cloud in their orbitals. +

78. Atoms, continued Electron Cloud Nucleus
99+% of the atom’s mass is made up of the protons and neutrons found in the nucleus.
The other <1% of the atom’s mass is found by adding up all the individual electrons.
The nucleus takes up less than 1% of the atom’s physical space… its volume, however.
99+% of the atoms actual space is the electron cloud where the electrons are zooming around at nearly the speed of light.
Technically, we are 99% empty space!
Nucleus

79. Technically, We Are 99.9% Empty Space?
Why do we appear solid?
Think about a plane propeller. Then image hundreds stacked on top of each other.
Our skin is hundreds of cells thick, constructed of millions of atoms each.

80. Why Do Things Feel Solid?
We actually feel very little that is solid.
What we feel is the interpretation of what solid is because of the electron clouds pushing away from one another.