1. Atoms and Their Interactions
Unit 2:
The Chemistry of Life
Atoms and Their Interactions
Unit Overview – pages

2. Section 6.1 Summary – pages 141-151
Elements
Everything – whether it is a rock, frog, or flower – is made of substances called elements.
Element: a substance that can’t be broken down into simpler chemical substances. It is made of one type of atom.
Section 6.1 Summary – pages

3. Section 6.1 Summary – pages 141-151
Natural elements in living things
Of the naturally occurring elements on Earth, only about 25 are essential to living organisms.
Carbon, hydrogen, oxygen, and nitrogen make up more than 96 percent of the mass of a human body.
Section 6.1 Summary – pages

4. Section 6.1 Summary – pages 141-151
Trace elements
Trace elements such as iron and copper, play a vital role in maintaining healthy cells in all organisms.
Plants obtain trace elements by absorbing them through their roots; animals get them from the foods they eat.
Section 6.1 Summary – pages

5. Section 6.1 Summary – pages 141-151
Table 6.1 Some Elements That Make Up the Human Body
Percent By Mass in Human Body
Percent By Mass in Human Body
Element
Symbol
Element
Symbol
Oxygen O
65.0
Iron Fe
trace
Carbon C
18.5
Zinc Zn
trace
Hydrogen H
9.5
Copper Cu
trace
Nitrogen N
3.3
Iodine I
trace
Calcium Ca
1.5
Manganese Mn
trace
Phosphorus P
1.0
Boron B
trace
Potassium K
0.4
Chromium Cr
trace
Sulfur S
0.3
Molybdenum Mo
trace
Sodium Na
0.2
Cobalt Co
trace
Chlorine Cl
0.2
Selenium Se
trace
Magnesium Mg
0.1
Fluorine F
trace
Section 6.1 Summary – pages

6. Section 6.1 Summary – pages 141-151
Atoms: The Building Blocks of Elements
Atom: the smallest particle of an element that has the characteristics of that element.
Atoms are the basic building blocks of all matter.
Section 6.1 Summary – pages

7. Section 6.1 Summary – pages 141-151
The Structure of an Atom:
Nucleus: the center of an atom
contain positively charged particles called protons (p+)
particles with no charge, called neutrons (n0).
Space surrounding the nucleus contains negatively charged particles called electrons (e-)
Section 6.1 Summary – pages

8. Draw and Label This in Your Notes

9. Section 6.1 Summary – pages 141-151
The Structure of an Atom
Nucleus
Electron energy levels
Section 6.1 Summary – pages

10. Section 6.1 Summary – pages 141-151
The Structure of an Atom
Protons and neutrons are approximately the same size and mass, however electrons are far smaller
Because opposites attract, the negatively charged electrons are held in the electron cloud by the positively charged nucleus.
Section 6.1 Summary – pages

11. Section 6.1 Summary – pages 141-151
Nucleus
Electron energy levels
8 protons (p+)
8 neutrons (n0)
Electrons exist around the nucleus in regions known as energy levels.
Oxygen atom
First energy level can hold two e-.
Second level can hold a maximum of eight e-.
Third level can hold up to 18 e-.
Section 6.1 Summary – pages

12. Section 6.1 Summary – pages 141-151
Electron energy levels
An atom of fluorine has nine electrons. How many electrons are in its second energy level?
Section 6.1 Summary – pages

13. Section 6.1 Summary – pages 141-151
Electron energy levels
Atoms contain equal numbers of electrons and protons; therefore, they have no net charge.
If an atom of fluorine has nine electrons, how many protons are in an atom of fluorine?
Section 6.1 Summary – pages

14. How many e- does phosphorous (P) have?
How many p+ does P have?
How do you know?

15. Section 6.1 Summary – pages 141-151
Isotopes of an Element
Atoms of the same element always have the same number of protons but may contain different numbers of neutrons.
Isotopes: atoms of the same element that have different numbers of neutrons
Carbon-12, carbon-13 and carbon-14 are examples of isotopes.
Section 6.1 Summary – pages

16. Section 6.1 Summary – pages 141-151
Compounds and Bonding:
Compound: a substance that is composed two or more different elements that are chemically combined.
Water (H20) Hydrogen and Oxygen by themselves are flammable – together they are stable…
Table salt (NaCl) is a compound composed of the elements sodium and chlorine.
Chemical formula
Section 6.1 Summary – pages

17. Section 6.1 Summary – pages 141-151
Bonds: Types and how they form
Atoms combine with other atoms to become more stable.
For many elements, an atom becomes stable when its outermost energy level is full.
Sharing electrons with other atoms is one way for elements to become stable.
Bonding is how they “share”
Section 6.1 Summary – pages

18. Section 6.1 Summary – pages 141-151
Covalent bond : an attractive force between two atoms that share electrons.
Molecule : a group of atoms held together by covalent bonds. It has no overall charge.
Water molecule
Section 6.1 Summary – pages

19. Section 6.1 Summary – pages 141-151
How covalent bonds form
Two hydrogen atoms can combine with each other by sharing their electrons.
Hydrogen molecule
Each atom becomes stable by sharing its electron with the other atom.
Think: full outer shell
Section 6.1 Summary – pages

20. Section 6.1 Summary – pages 141-151
Ionic bonds
An atom (or group of atoms) that gains or loses electrons and has an electrical charge and is called an ion.
Ionic bond : attractive force between two ions of opposite charge
Example: A chlorine atom becomes a chloride ion when it gains an electron.
Section 6.1 Summary – pages

21. Hydrogen Bonds Biological bonds
Weak bonds (think magnet) between hydrogen (H+) and oxygen (O-).
Unequal sharing of electrons making it a polar molecule
Hydrogen bonds give water unique properties

22. Hydrogen Bonds Unique properties of water due to H bonds:
Universal solvent
Can bond with other water molecules and molecules of other substances
Water has a greater resists to changes in temperature (boiling and freezing)
Found in all 3 states: gas, a liquid, and a solid
Less dense when in a solid state
Helps in temperature regulation of all organisms on earth

23. Section 6.1 Summary – pages 141-151
Bonds and Chemical Reactions:
How are bonds and chemical reactions “related” ?
Chemical reactions occur when bonds are formed or broken.
Causes substances to recombine into different substances (ex. burning paper).
What do you think “Drives” all the breaking and forming of bonds?
ENERGY!!!
Section 6.1 Summary – pages

24. Section 6.1 Summary – pages 141-151
Chemical Reactions:
In a chemical reaction there are two parts: Reactants and Products
Section 6.1 Summary – pages

25. Section 6.1 Summary – pages 141-151
Chemical Reactions as Chemical Equations
2H + O2 = H2O - chemical equation of Water
Chemical equations
Show bonds being broken and formed
They show the Law of Conservation of Mass (atoms are neither created nor destroyed in chemical reactions. They are simply rearranged.)
Section 6.1 Summary – pages

27. Section 6.1 Summary – pages 141-151
Mixtures and Solutions:
Mixture : a combination of substances in which the individual components retain their own properties.
Neither component of the mixture changes.
Salad, chex mix, sand and water
Section 6.1 Summary – pages

28. Section 6.1 Summary – pages 141-151
Mixtures and Solutions
Solution : a mixture in which one or more substances (solutes) are distributed evenly in another substance (solvent).
Kool-aid, hot cocoa
Section 6.1 Summary – pages

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30. Section 6.1 Summary – pages 141-151
Acids and Bases:
Chemical reactions can occur only when conditions are right.
A reaction may depend on:
- energy availability
- temperature
- concentration of a substance
- pH of the surrounding environment
Section 6.1 Summary – pages

31. Section 6.1 Summary – pages 141-151
Acids and bases
pH : a measure of how acidic or basic a solution is.
A scale with values ranging from below 0 to above 14 is used to measure pH.
More acidic
Neutral
More basic
Draw a pH scale in your notes
Section 6.1 Summary – pages

32. Section 6.1 Summary – pages 141-151
Acids and bases
pH below 7 are acidic.
Acid : any substance that forms hydrogen ions (H+) in water
More acidic
Neutral
More basic
Section 6.1 Summary – pages

33. Section 6.1 Summary – pages 141-151
Acids and bases
Substances with a pH above 7 are basic or alkaline.
Base : any substance that forms hydroxide ions (OH-) in water.
pH 11
Section 6.1 Summary – pages

34. The Chemistry of Life The Life of a Cell
Organic Compounds: Macromolecules
Unit Overview – pages

35. 6.3 Section Summary 6.3 – pages 157-163
The Role of Carbon in Organisms:
Carbon compounds that come from living organisms are called organic compounds.
Two carbon atoms can form various types of covalent bonds—single, double or triple.
6.3 Section Summary 6.3 – pages

36. 6.3 Section Summary 6.3 – pages 157-163
Molecular chains:
The small molecules, monomers, bond together to form large chains called polymers.
Polymer : a large molecule formed when many smaller molecules bond together.
Polymers usually form by covalent bonding.
6.3 Section Summary 6.3 – pages

37. The 4 Main Organic Compounds:
Main Function:
1. Provide energy
Store energy & Insulation
Stores genetic information
Controls the rate of cell reactions &
Forms cell structures
Macromolecule:
Carbohydrates
Lipids
Nucleic Acids
Proteins

38. 6.3 Section Summary 6.3 – pages 157-163
The structure of carbohydrates:
Carbohydrate : composed of carbon, hydrogen, and oxygen with a ratio of about two hydrogen atoms and one oxygen atom for every carbon atom.
6.3 Section Summary 6.3 – pages

39. 6.3 Section Summary 6.3 – pages 157-163
The structure of carbohydrates
Monosaccharide : the simplest type of carbohydrate; a simple sugar (ie. glucose, fructose)
Glucose and fructose combine in a condensation reaction to form sucrose (table sugar)
Which is the reactant and which is the product?
6.3 Section Summary 6.3 – pages

40. 6.3 Section Summary 6.3 – pages 157-163
The structure of carbohydrates
The largest carbohydrate molecules are polysaccharides, composed of many monosaccharide subunits. (ie. potatoes, liver)
Which is the monomer?
Which is the polymer?
Write the monomers and polymers in your notes
6.3 Section Summary 6.3 – pages

41. 6.3 Section Summary 6.3 – pages 157-163
The structure of lipids:
Lipids : large biomolecules that are made mostly of carbon and hydrogen with a small amount of oxygen. (ie. fats, oils, waxes)
6.3 Section Summary 6.3 – pages

42. 6.3 Section Summary 6.3 – pages 157-163
The structure of lipids
They are insoluble in water because their molecules are nonpolar and hydrophobic
(hydro) (phobic)
6.3 Section Summary 6.3 – pages

43. 6.3 Section Summary 6.3 – pages 157-163
Draw an example in your notes
The structure of lipids
A fatty acid with single bonds is saturated; with double bonds is unsaturated
A fatty acid is a monomer of a lipid
A fatty acid and glycerol is a monomer of a lipid
6.3 Section Summary 6.3 – pages

44. 6.3 Section Summary 6.3 – pages 157-163
The structure of proteins:
Protein : a large, complex polymer composed of carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur.
6.3 Section Summary 6.3 – pages

45. 6.3 Section Summary 6.3 – pages 157-163
The structure of proteins
Amino acids : the basic building blocks of proteins—amino acid is a monomer of a protein
There are about 20 common amino acids that can make literally thousands of proteins.
6.3 Section Summary 6.3 – pages

46. 6.3 Section Summary 6.3 – pages 157-163
The structure of proteins
Peptide bonds : covalent bonds formed between amino acids.
6.3 Section Summary 6.3 – pages

47. 6.3 Section Summary 6.3 – pages 157-163
The structure of proteins
Proteins are the building blocks of many structural components of organisms.
Enzymes are important proteins found in living things.
They speed the reactions in digestion of food.
6.3 Section Summary 6.3 – pages

48. The structure of proteins
Enzyme : a protein that changes the rate of a chemical reaction.
The sum of all the chemical reactions occurring in an organism is its Metabolism.

49. 6.3 Section Summary 6.3 – pages 157-163
The structure of nucleic acids:
Nucleic acid : a complex biomolecule that stores cellular information in the form of a code.
Nucleotides : small subunits that make up nucleic acids—nucleotides are the monomers of nucleic acids.
6.3 Section Summary 6.3 – pages

50. 6.3 Section Summary 6.3 – pages 157-163
The structure of nucleic acids
Nucleotides are arranged in three groups—a nitrogenous base, a simple sugar, and a phosphate group.
Phosphate
Sugar
Nitrogenous base
6.3 Section Summary 6.3 – pages

51. Draw This in Your Notes

52. 6.3 Section Summary 6.3 – pages 157-163
The structure of nucleic acids
DNA, which stands for deoxyribonucleic acid is a nucleic acid.
Phosphate
Sugar
Nitrogenous base
6.3 Section Summary 6.3 – pages

53. 6.3 Section Summary 6.3 – pages 157-163
The structure of nucleic acids
The information coded in DNA contains the instructions used to form all of an organism’s enzymes and structural proteins.
Another important nucleic acid is RNA, which stands for ribonucleic acid. RNA is a nucleic acid that forms a copy of DNA for use in making proteins.
6.3 Section Summary 6.3 – pages