1. KEY CONCEPT All living things are based on atoms and their interactions.

2. Objectives
Identify elements common to all living things
Describe how ions form
Compare ionic and covalent bonding

3. Atom Element Compound Ion Ionic bond Covalent bond Molecule Proton
Vocabulary
Atom
Element
Compound
Ion
Ionic bond
Covalent bond
Molecule
Proton
Neutron
Electron
Nucleus
Atomic Number
Atomic Mass

4. Living things consist of atoms of different elements.
An atom is the smallest basic unit of matter.
An element is one type of atom.
Hydrogen atom (H) H O
Oxygen atom (O)

5. An atom has a nucleus and electrons.
The nucleus has protons and neutrons.
Electrons are in energy levels outside nucleus.
The outermost energy level determines the activity of the atom
Oxygen atom (O)
Nucleus: 8 protons (+) 8 neutrons
outermost energy level: 6 electrons (-)
inner energy level: 2 electrons (-)

6. The number of protons distinguishes one element from another
Each element has a different number of protons neutrons and electrons than any other element
A particular element always has the same # of protons you know how many protons an element has by looking at the periodic table
The atomic # always identifies the number of protons
The atomic mass always tells you the sum of protons + neutrons + electrons

7. You can use the periodic table to determine the number of neutrons in an atom
Protons + neutrons = atomic mass
Atomic Mass- protons = neutrons
If you subtract the number of protons from the atomic mass it will tell you how many neutrons are in an atom

8. Atoms want to be stable
Electrons are in energy levels outside nucleus.
Energy levels want to be full of electrons
Each level can hold a different number of electrons
1st energy level wants 2e-
2nd energy level wants 8 electrons
3rd energy level wants either 8 or 18
Lower energy levels always fill up before higher energy levels
If the energy level isn’t full, the atom is not stable and will react with other atoms and form bonds!

9. Atoms can gain, lose or share electrons to become stable
Different atoms have different numbers of energy levels
The outermost energy level of an atom is called its valence shell
Electrons in the outermost energy level are called valence electrons
It’s the valence electrons that determine
what types of bonds will form
How many bonds will form

10. A compound is made of atoms of different elements bonded together.
carbon dioxide (CO2)

11. Different Compounds are held together by different types of bonds
Covalent Bonds
Ionic Bonds
Hydrogen Bonds

12. Valence Electron Configuration
Hydrogen 1H 2 He
4.00
Atomic number
Helium
2He
Mass number
Element symbol
First
shell
Electron
distribution
diagram
Lithium
3Li
Beryllium
4Be
Boron 5B
Carbon 6C
Nitrogen 7N
Oxygen 8O
Fluorine 9F
Neon
10Ne
Second
shell
Sodium
11Na
Magnesium
12Mg
Aluminum
13Al
Silicon
14Si
Phosphorus
15P
Sulfur
16S
Chlorine
17Cl
Argon
18Ar
Figure 2.9 Electron distribution diagrams for the first 18 elements in the periodic table.
Third
shell 12

13. Atoms share pairs of electrons in covalent bonds.
A covalent bond forms when atoms share a pair of electrons.
The number of covalent bonds depends on the number of valence electrons an atom has to share
Compounds held together by covalent bonds are called molecules
covalent bonds
Oxygen atom (O)
Carbon atom (C)
Carbon dioxide (CO2 )

14. Covalent bonds are when atoms share electrons
Sometimes its easier for an atom to gain or lose an electron than to share
Atoms that gain electrons
Are called anions
what kind of charge will an anion have?
Atoms that lose electrons
Are called cations
what kind of charge will an cation have?

15. Ions form when atoms gain or lose electrons.
An ion is an atom that has gained or lost one or more electrons.
Ionic bonds form between oppositely charged ions.
Opposites Attract
The type of bond that will form depends on the number of valence electrons
Sodium atom (Na)
Chlorine atom (CI)
Sodium ion (Na+)
Chloride ion (CI-)
Na loses an electron to CI
ionic bond
gained electron

16. What distinguishes one element from another?
The number of protons in the nucleus

17. Describe the formation of an ionic compound
One atom gives up an electron, another atom picks up that electron
The atom that loses the electron has a positive charge
The atom that gains the electron has a negative charge
The two oppositely charged ions are attracted to each other and form an ionic bond

18. What is the difference between an ionic and a covalent bond?
An ionic bond is formed due to the electrical attraction between oppositely charged ions
A covalent bond is formed by a shared pair of electrons

19. How does a molecule differ from an atom?
A molecule is made up of 2 or more atoms held together by covalent bonds

20. Explain why a Hydrogen atom can become either an ion or a part of a molecule?
A hydrogen atom has one unpaired electron in its outer energy level
The electron can either be lost to form an ion, or shared to form a covalent bond

21. A sodium atom has one outer electron, and a carbon atom has 4 outer electrons. How might this difference be related to types of compounds formed by atoms of these 2 elements?
An atom that has a nearly full or nearly empty energy level (such as sodium) tends to form ions
An atom in between (such as carbon) tends to share electrons

22. KEY CONCEPT Water’s unique properties allow life to exist on Earth.

23. Objectives
Recognize the importance of hydrogen bonding
Explain why many compounds dissolve in water
Compare acids and bases

24. Vocabulary
Hydrogen bond
Cohesion
Adhesion
Solution
Solvent
Solute
Acid
Base pH
Hydrogen ion

25. Life depends on hydrogen bonds in water.
Water is the only common substance found naturally in all three common states of matter and it is essential for all life on Earth
What kind of bonds are holding these 2 hydrogen atoms to the oxygen in this compound?

26. Life depends on hydrogen bonds in water.
Its true that these are covalent bonds holding the hydrogen atoms to the oxygen and so they are sharing electrons O H
BUT oxygen does not share the electrons equally with the hydrogen atoms
Electrons spend more time on the oxygen side than the hydrogen side
What kind of charge will oxygen have?

27. Life depends on hydrogen bonds in water.
Water is a polar molecule.
Polar molecules have slightly charged regions. O H _ +
Nonpolar molecules do not have charged regions.
Hydrogen bonds form between slightly positive    hydrogen atoms and slightly negative atoms.

28. Hydrogen bonds are responsible for three important properties of water.
high specific heat
cohesion
adhesion

29. Specific Heat Capacity
Specific Heat is the amount of heat per unit mass required to raise the temperature by one degree Celsius
Water has a high specific heat capacity
This means it requires a lot of heat energy to raise the temperature of water
This allows water to moderate Earth's climate by buffering large fluctuations in temperature
Because water can absorb the heat from the air when its hotter, and release the heat when its cooler outside

30. Heat of vaporization
The energy required to transform a given quantity of a substance from a liquid into a gas
Water has a high heat of vaporization
Organisms exploit this in a process called evaporative cooling
As water evaporates it absorbs heat from the environment, leaving it cooler

31. Capillary Action and Surface Tension are products of adhesion & cohesion
Water molecules are attracted to other water molecules
Water sticks to itself
Water molecules are attracted to other polar molecules
Water sticks to things
EX: water sticks to the side of you cold soda cup on a hot day

32. Surface Tension Capillary Action
Capillary Action and Surface Tension are products of adhesion & cohesion
Surface Tension
Capillary Action
A thin “skin” across the surface of water due to cohesion
water rises into a narrow tube against the force of gravity.
Water adheres to the inside wall of the tube and surface tension tends to straighten the surface causing a surface rise and more water is pulled up through cohesion

33. Many compounds dissolve in water.
A solution is formed when one substance dissolves in another.
A solution is a homogeneous mixture.
Solvents dissolve other substances.
Solutes dissolve in a solvent.
solution

34. “Like dissolves like.”
Polar solvents dissolve polar solutes.
Hydrophilic: water loving
Nonpolar solvents dissolve nonpolar solutes.
Hydrophobic: water fearing
Polar substances and nonpolar substances generally remain separate.
think oil (nonpolar) & water
vinegar (polar) & water

35. Some compounds form acids or bases.
An acid releases a hydrogen ion (H+) when it dissolves in water.
high H+ concentration
pH less than 7
more acidic
stomach acid pH between 1 and 3

36. A base removes hydrogen ions from a solution.
low H+ concentration
pH greater than 7
bile pH between 8 and 9
more basic

37. A neutral solution has a pH of 7.
pure water pH 7

38. What causes a molecule to be polar?
Unequal sharing of electrons between atoms

39. How do polar molecules form hydrogen bonds?
The oppositely charged regions of a polar molecule attract other polar molecules, allowing positively charged hydrogen atoms to bond to a negatively charged atom

40. What are some of waters properties
Its found in all three phases (solid, liquid, gas) on earth
High specific heat
High heat of vaporization
Adhesion
Cohesion

41. How do organisms depend on waters properties to survive
Ice floats because its less dense allowing organisms to live on the ice or under , and acts as an insulator
Organisms utilize evaporative cooling (via sweating) to maintain proper body temperature
Plants use waters cohesive and adhesive properties to perform capillary action and transpiration
Animals and insects can walk or lay eggs on water due to its surface tension
Climate is regulated due to waters high specific heat
Water is an important solvent in which many chemical reactions take place

42. What determines whether a compound will dissolve in water
Compounds that have charges, such as ionic compounds (like table salt) and polar molecules (like sugar) will dissolve in water

43. Make a chart that compares acids and bases
Donates protons
In solution has a high H+ ion concentration
pH below 7
Accept protons
In solution has a low H+ concentration & a high concentration of OH- ions
Has a pH above 7

44. How do polar molecules differ from nonpolar molecules
How do polar molecules differ from nonpolar molecules? How does this difference affect their interaction?
Polar molecules have charged regions due to unequal sharing of electrons.
Nonpolar molecules do not have charged regions because electrons are shared more equally
The charge differences between polar and nonpolar molecules tend to keep the molecules separate

45. Describe an example of cohesion or adhesion that you might observe in your daily life
Cohesions: water beading on the surface of an object
Adhesions: water sticking to the outside of a milkshake cup on a hot day

46. When sugars are broken down to produce usable energy a large amount of heat is released. Explain how the water inside a cell helps to keep the cells temperature constant.
Water has a high specific heat
Specific heat: a measure of how much something resists temperature changes
Water in a cell can absorb a large amount of energy before its temperature increases

47. KEY CONCEPT Carbon-based molecules are the foundation of life.

48. Objectives
Describe the bonding properties of carbon atoms
Compare carbohydrates, proteins, lipids, and nucleic acids

49. Monomer Polymer Carbohydrate Monosaccharide Lipid Phospholipid Starch
Vocabulary
Monomer
Polymer
Carbohydrate
Monosaccharide
Lipid
Phospholipid
Starch
Cellulose
Protein
Amino acid
Peptide bond
Nucleic acid
Nucleotide
Glycogen
Chitin
Primary structure
Secondary structure
Tertiary structure
Quaternary structure

50. Carbon atoms have unique bonding properties.
How many electrons does a carbon atom have?
How many of those electrons are valence electrons?
How many more electrons does carbon need to be stable?
How many covalent bonds do you think carbon will make to accomplish this?

51. Carbon atoms have unique bonding properties.
Carbon forms covalent bonds with up to four other atoms, including other carbon atoms.
Carbon-based molecules have three general types of structures.
straight chain
branched chain
ring

52. Many carbon-based molecules are made of many small subunits called monomers bonded together to form polymers.
Monomers are the individual subunits.
Polymers are made of many monomers.

53. Four main types of carbon-based molecules are found in living things.
Carbohydrates are made of carbon, hydrogen, and oxygen.
Notice the ratio of C:H:O
This ratio is maintained for ALL sugars

54. Four main types of carbon-based molecules are found in living things.
Carbohydrates include sugars and starches
MonomersMonosaccharides
Glucose
Fructose
Galactose
Polymers Polysaccharides
Starches
Cellulose
Glycogen
Chitin

55. Carbohydrates can be broken down to provide energy for cells.
Some carbohydrates are part of cell structure.
Polymer (starch)
Starch is a polymer of glucose monomers that often has a branched structure.
Polymer (cellulose)
Cellulose is a polymer of glucose monomers that has a straight, rigid structure
monomer

56. Many contain carbon chains called fatty acids.
Lipids are nonpolar molecules that include fats, oils, and cholesterol.
Many contain carbon chains called fatty acids.
Fats and oils contain fatty acids bonded to glycerol.
Triglyceride

57. Lipids have several different functions.
broken down as a source of energy
make up cell membranes
used to make hormones

58. Fats and oils have different types of fatty acids.
saturated fatty acids
unsaturated fatty acids

59. Phospholipids make up all cell membranes.
Polar phosphate “head”
Nonpolar fatty acid “tails”
Phospholipid

60. Proteins are polymers of amino acid monomers.
Twenty different amino acids are used to build proteins in organisms.

61. Proteins are polymers of amino acid monomers.
Twenty different amino acids are used to build proteins in organisms.
Amino acids differ in side groups, or R groups.

62. Proteins are polymers of amino acid monomers.
Twenty different amino acids are used to build proteins in organisms.
Amino acids differ in side groups, or R groups.
Amino acids are linked by peptide bonds.

63. Proteins differ in the number and order of amino acids.
Amino acids interact to give a protein its shape.
hydrogen bond
Hemoglobin
Incorrect amino acids change a protein’s structure and function.

65. Nucleic acids are polymers of monomers called nucleotides.

66. Nucleic acids are polymers of monomers called nucleotides.
Nucleotides are made of a sugar, phosphate group, and a nitrogen base.
A phosphate group
nitrogen-containing molecule, called a base
deoxyribose (sugar)

67. Nucleic acids are polymers of monomers called nucleotides.
Nucleotides are made of a sugar, phosphate group, and a nitrogen base.
DNA
DNA stores genetic information .
RNA is used to build proteins.
RNA

68. What is the relationship between a polymer and a monomer
A polymer is a large molecule made up of many smaller units called monomers that are linked together

69. Explain how both nucleic acids and proteins are are polymers
Explain how both nucleic acids and proteins are are polymers. Be sure to describe the monomers that make up the polymers.
Proteins
Nucleic Acids
Composed of monomers called amino acids
There are 20 different amino acids to choose from
Composed of monomers called Nucleotides
Each nucleotide consists of a sugar, phosphate group, and nitrogenous base
They’re both polymers because they’re both made of smaller units bonded together

70. How are carbohydrates and lipids similar? How are they different
Includes sugars and starches
Shorter term energy storage
Cellulose in plant cell walls and chitin in fungi cell walls
-Both
made of
C,H, & O
-Broken down as a source of energy
-Have some structural functions
Includes fats, oils, and waxes
Longer term energy storage
Phospholipids in the plasma membrane

71. Explain how the bonding properties of carbon atoms result in the large variety of carbon-based molecules in living things
Carbon atoms are able to form 4 covalent bonds with other atoms including other carbon atoms
Many other types of atoms can bind to carbon, and many different combinations are possible

72. Why might fatty acids, amino acids, and nucleic acids increase the hydrogen ion (H+) concentration of a solution? Explain your answer.
These molecules are all acids
Acids, by definition, increase the H+ ion concentration of a solution, and there by lower the pH

73. KEY CONCEPT Life depends on chemical reactions.

74. Objectives
Describe how bonds break and reform during chemical reactions
Explain why chemical reactions release or absorb energy

75. Vocabulary
Chemical reaction
Reactant
Product
Bond energy
Equilibrium
Activation energy
Endothermic
Exothermic

76. Bonds break and form during chemical reactions.
Chemical reactions change substances into different ones by breaking and forming chemical bonds.
Reactants are changed during a chemical reaction.
Products are made by a chemical reaction.

77. Bond energy is the amount of energy that breaks a bond.
Energy is added to break bonds.
Energy is released when bonds form.
A reaction is at equilibrium when reactants and products form at the same rate.
CO2 + H2O H2CO3

78. Chemical reactions release or absorb energy.
Activation energy is the amount of energy that needs to be absorbed to start a chemical reaction.

79. Exothermic reactions release more energy than they absorb.
Reactants have higher bond energies than products.
Excess energy is released by the reaction.

80. Endothermic reactions absorb more energy than they release.
Reactants have lower bond energies than products.
Energy is absorbed by the reaction to make up the difference.

81. Hydrogen peroxide (H2O2) breaks down into water (H2O) and oxygen (O2)
Hydrogen peroxide (H2O2) breaks down into water (H2O) and oxygen (O2). A) Explain why this is a chemical reaction. B) what are the reactants? C) what are the products?
A) it is a chemical reaction because different substances are formed
B) reactant = Hydrogen peroxide (H2O2)
C) products = water (H2O) and oxygen (O2)

82. How do endothermic and exothermic reactions differ?
Endothermic reactions absorb energy because the products have a higher bond energy than the reactants have
Exothermic reactions release energy because the products have a lower bond energy than the reactants have

83. The process below is exothermic
The process below is exothermic. What must be true about the bond energies of the reactants and the products? Explain. 6O2 + C6H12O6  6CO2 + 6H2O
The bond energies of the reactants must be higher than those of the products because energy is released.

84. Why might it not always be possible to determine the reactants and the products in a reaction? Explain your answer in terms of chemical equilibrium.
Depending on the concentrations of the reactants and the products, both reactants and products may be formed at the same time if the reaction is reversible.
At equilibrium, reactants and products are formed at the same rate

85. A chemical reaction can start when enough activation energy is added to the reactants. Do you think the activation energy for chemical reactions in living things is high or low? Explain your answer.
The activation energy for reactions must be relatively low because temperature can not be greatly increased in living things.

86. KEY CONCEPT Enzymes are catalysts for chemical reactions in living things.

87. Objectives
Explain the effect of a catalyst on activation energy
Describe how enzymes regulate chemical reactions

88. Vocabulary
Catalyst
Enzyme
Substrate
Active site

89. A catalyst lowers activation energy.
Catalysts are substances that speed up chemical reactions.
decrease activation energy
increase reaction rate

90. Enzymes allow chemical reactions to occur under tightly controlled conditions.
Enzymes are catalysts in living things.
Enzymes are needed for almost all processes.
Most enzymes are proteins.

91. Disruptions in homeostasis can prevent enzymes from functioning.
Enzymes function best in a small range of conditions.
Changes in temperature and pH can break hydrogen bonds.
An enzyme’s function depends on its structure.

92. An enzyme’s structure allows only certain reactants to bind to the enzyme.
substrates
active site
substrates (reactants)
enzyme
Substrates bind to an enzyme at certain places called active sites.

93. The lock-and-key model helps illustrate how enzymes function.
substrates brought together
bonds in substrates weakened
Substrates bind to an enzyme at certain places called active sites.
The enzyme brings substrates together and weakens their bonds.
The catalyzed reaction forms a product that is released from the enzyme.

94. How does a catalyst affect the activation energy and rate of a reaction
A catalyst reduces the activation energy required to start a reaction
A catalyst speeds up the rate of chemical reactions

95. Describe how the interaction between an enzyme and its substrates changes a chemical reaction
An enzyme brings substrates close together and slightly alters (weakens) the bonds within the substrates by changing the shapes of the molecules so that they can react

96. Some organisms live in very hot or acidic environments
Some organisms live in very hot or acidic environments. Would their enzymes function in a persons cells? Why or why not? NO
Those enzymes function optimally under different conditions than those found in a person

97. Suppose that the amino acids that make up an enzymes active site are changed. How might this change affect the enzyme?
The substrates would likely not bond to the enzyme because the shape of the active site would change.

98. Organisms need to maintain homeostasis, or stable internal conditions
Organisms need to maintain homeostasis, or stable internal conditions. Why is homeostasis important for the function of enzymes?
If homeostatic conditions, such as temperature, ionic (salt) concentrations, or pH are not maintained, then the hydrogen bonds that keep an enzyme in its correct shape will weaken or break and the enzymes structure will change.
Because enzymes function is determined by their structure, changing their shape will affect their function