1. Chemical Foundations of Life

2. The atom – the basic unit of matter
Subatomic particles:
Protons – inside nucleus, + charge
Neutrons – inside nucleus, no charge
Electrons – constant motion in orbit, - charge
What is the difference between an atom and an element?
What is a molecule? What is a compound? Hint: All compounds are molecules but not all molecules are compounds.

3. Element – made up of only one type of atom Ex. Hydrogen (H)
What is the difference between an atom and an element?
What is a molecule? What is a compound? Hint: All compounds are molecules but not all molecules are compounds.

4. Each different element has a different number of protons in its atomic nucleus
Atoms of the same element always have the same number of protons, but can vary in the number of neutrons.
Elements
What distinguishes one element from another? What can vary between atoms of the same element? What do we call the variations?

5. Elements
On the periodic table, elements are shown with numbers that indicate:
Atomic # = # of protons
Atomic mass/ weight = # protons + # neutrons
Chemical name (full name)
Chemical Symbol
What distinguishes one element from another? What can vary between atoms of the same element? What do we call the variations?

6. Periodic Table of Elements

7. SPONCH and more . . . You need to know the elements SPONCH S = Sulfur
P = Phosphorus
O = Oxygen
N = Nitrogen
C = Carbon
H = Hydrogen

8. Elements of life
The four most common elements in the human body are oxygen, carbon, hydrogen, and nitrogen.
These and the other 7 elements in the table to the left are called essential elements.
Elements that we need in very tiny amounts, like iron, are called trace elements.
Iron, iodine

9. C O H N Carbon (C) Oxygen (O) Hydrogen (H) Nitrogen (N) 8 6 1 7
Atomic Number... 6
Atomic Mass 8 6 C
12.011 O
15.999 1 7 H
1.008 N
14.007
Hydrogen (H) Nitrogen (N)

10. Electrons and Bonding
Electrons fill the orbital shells from the inside out: 2, 8, 8 maximum in the first 3 levels.
Elements with full outer levels are stable and chemically inactive. Ex. He, Ne, Ar
Elements with unfilled outer levels will interact with other atoms - bonding

11. Electrons and bonding Valence electrons (outer shell)

12. Properties of elements
The number of electrons in the outermost valence shell determines how the atom will react with other atoms.
What kinds of subatomic particles are found in the shell? What is another name for shell? Why is important to know how many electrons are in the outermost shells of atoms?

13. Electrons and Bonding
element = simplest form of matter with properties
ex. hydrogen (H)
compound = 2 or more elements bonded in a particular proportion
ex. H2O (water)
molecule = 2 or more atoms bonded together ex. H2 (hydrogen gas), H2O (water)

14. Ionic Bonds
An atom gives away or takes an electron to complete the outer valence shell.
This results in oppositely charged atoms, or ions.
In an ionic bond, are the atoms physically connected to each other?

15. Ionic Bonds
The oppositely charged ions are attracted to each other, like the the opposite poles of magnets
Ex. Na+Cl-, sodium chloride
In an ionic bond, are the atoms physically connected to each other?

16. Covalent Bonds Atoms share pairs of electrons
This results in the atoms being physically linked to each other.
What is going on with electrons in hydrogen and oxygen molecules? Are they transferred from one atom to another?
When two atoms share electrons equally, what do we call that bond?

17. Nonpolar Covalent Bonds
Sometimes the atoms share electrons equally, this is called a nonpolar covalent bond.
Example:
C (carbon) can share an electron with each H (hydrogen)
Each H shares its electron with C also
What is going on with electrons in hydrogen and oxygen molecules? Are they transferred from one atom to another?
When two atoms share electrons equally, what do we call that bond?

18. Polar Covalent Bonds
Sometimes atoms do not share electrons equally because one atom is more electronegative than the other.
Electronegativity is the ability to attract electrons.
This unequal sharing of electron pairs is called a polar covalent bond.
When atoms in a molecule do not share electrons equally, what is the bond called? Is water an ion? Does it have a charge?

19. Water! Covers 75% of the Earth’s surface
Most abundant compound in most living organisms

20. Intramolecular properties of water
Intramolecular means within the molecule.
Each water molecule has two polar covalent bonds.
The unequal sharing of electrons between oxygen and hydrogen leads to charged regions within the molecule.

21. Intermolecular properties of water
Intermolecular means between two molecules of water.
Negative region on the oxygen atom of one molecule is attracted to the positive region on the hydrogen atom of another molecule.
We call the attraction a hydrogen bond.

22. Emergent properties of water
Cohesion is the sticking together of water molecules with hydrogen bonds.

23. Emergent properties of water
Surface tension is like water molecules all holding hands on the top of the water
It allows insects and spiders walk on surface

24. Unit 1: Biochemistry and Digestion

25. Basilisk lizard!
Surface tension and rapid movement
See video

26. Unit 1: Biochemistry and Digestion

27. Unit 1: Biochemistry and Digestion

28. Emergent properties of water
Adhesion is the sticking of water molecules to other polar or charged molecules.

29. Emergent properties of water
Water is called the “Universal solvent” because it can dissolve many polar or ionic compounds
Hydrophilic, hydrophobic, polar, nonpolar

30. Solution Mixture with one substance dissolving into the other
Solute – substance being dissolved
Solvent – substance that does the dissolving
Ex. – sugar (solute) in water (solvent)

31. Solutions
Ionically bonded compounds dissolve in water, breaking into individual ions
NaCl  Na+ + Cl-
Negative oxygen regions of polar water molecules are attracted to sodium cations (Na+). +
Cl – –
Na+
Positive hydrogen regions of water molecules cling to chloride anions (Cl–).
Cl–

32. Acids and Bases
Acid – substance that releases hydrogen ions (H+) into solution
HCl  H+ + Cl-
Base – substance that releases hydroxide ions (OH-) into solution or lowers H+
NaOH  Na+ + OH-
OH- + H+  H2O
Both can be highly reactive and dangerous

33. Acidic solution Neutral solution Basic solution
Figure 2.14_3
Acidic solution
Neutral solution
Basic solution
Figure 2.14_3 The pH scale reflects the relative concentrations of H and OH
(part 3). 33

34. pH scale How do we know how acidic or basic something is?
pH scale represents the acidity of solution and the relative concentrations of OH- and H+
Range between 0 and 14
Pure water has pH 7 (equal concentrations of OH- and H+)
Where in your body do you think you’d find strong acids? (stomach)

35. pH values
Most cells have pH range pH

36. Buffers pH of cells must be kept ~7 Control pH with buffers
pH affects the shape of molecules
The shape of molecules affects their function
So, pH can affect cellular function by interfering with molecular function
Control pH with buffers
Group of compounds that can
donate H+ when [H+] falls
absorb H+ when [H+] rises
Exercise = acidic in muscles
CO2 = carbonic acid
lactic acid
body uses buffers to counter act this
When the body maintains a current level of something, what do we call that?

37. Example: buffers in the blood
pH of human blood is 7.4
Drops to 7.0 or increases to 7.8 are lethal after even a few minutes
Blood maintains pH using these compounds:
Bicarbonate HCO3- accepts --> H2CO3
Carbonic acid H2CO3 donates --> HCO3-

38. Water Olympics Station 1: Nerigula and Amir Station 2:
Station 3: Dylan and Lilly
Station 4:
Station 5: Zoya and Julianne
Station 6: