1. Introduction to Biochemistry Textbook Chapters (2.1 and 2.2)
Essential Questions:
What are atoms?
What are they made of?
How do they react to each other?
Why are they important for your body?

3. Background
Atom – smallest particle of an element that retains the characteristics of that element.
Element – the most simple chemical substance made of
only 1 type of atom.
All are arranged in the periodic table.
Columns and rows
Each element is identified via 1, 2 or 3 letter abbreviation.
According to the table, what is the symbol for Hydrogen? H H

5. Structure of an Atom Composed of a Nucleus Contains Protons (p+)‏
Contains Neutrons (n0)‏
Protons + Neutrons = Atomic Mass
# protons = Atomic Number
Surrounded by Electrons (smaller particles) with negative (e-) charges.
Travel in regions called energy levels
2 electrons in the inner shell
8 electrons in the outer shell
(There are more, you’ll learn those in advanced courses.)
What important biological element am I?
Carbon! All living things are made of carbon, which is why they are called “Organic.”

6. Crash course on the Periodic Table
Columns go up and down
Rows go left and right
Metals are left of the zigzag, Nonmetals to the right (except H)‏
Elements are uncharged, which means the number of protons (+) MUST EQUAL the number of electrons (-)
Column numbers tell you valence shell electron number
I.e. their bonding pattern
Atoms bond together then they don’t have enough electrons in their outermost shell.
“Valence” shell electrons are the outermost electrons on an atom.
Hydrogen is in column 1, so it has 1 valence e-
Oxygen is in column 16, so it has 6 valence e-
Carbon is in column 14, so it has 4 valence e-
Nitrogen is in column 15, so it has 5 valence e-
Neon is in column 18, so it has 8 valence e-, these are the “Noble Gases” which all have full valence shells and won’t bond to any other atoms.
____________ _________ato m am I?

7. Your Turn: How many Valence Electrons?3 4 5

8. What kind of Patterns do you see?

9. Ionic Bonding
Elements become “happy” when they have a full valence electron shell
2, 8, 18, etc
With elements only 1 or 2 electrons away from a full shell will lose or gain electrons.
Bonds between metals and nonmetals.
The charge between the elements keeps them attracted together (now called ions)‏
Compound – atoms held together by ionic bonds.

10. Covalent Bonding
When elements have about 4 electrons to gain or lose, they elect to share electrons!
Saves energy; easier to share than to steal or give up!
Occurs between nonmetals.
Water uses covalent bonds.
Covalent Bonds are the most common in Biology.
Molecule – atoms held together by covalent bonds.

11. Isotopes
Isotopes – atoms of the same element that contain different numbers of neutrons.
Isotopes are used to date once living things like mummies and dinosaurs!
How many Neutrons does Carbon-12 have?
How many Neutrons does Carbon-13 have?
How many Neutrons does Carbon-14 have? 6 7 8

12. Your Turn! Let’s Review:
What type of bonding is when a few electrons are transferred (taken or lost)?
Ionic Bonding
What type of bonding is when more electrons are shared?
Covalent Bonding
What part of the atom (p+, n0 or e-) is responsible for how an atom reacts to another atom?
Electrons (e-)
In what case will an atom not react to another atom?
When their valence electron shell is full (2, 8, etc) or when it is full by bonding (ionic or covalent) to 1 or more atoms.

13. Case Study: Hemoglobin
How does Oxygen & Carbon Dioxide bond itself to the Iron in your blood cells?
Why is it important that these two (Oxygen and CO2) bond well to Iron atoms in the heme molecules?

14. Question/Problem: Why is Carbon Monoxide deadly?
Record an observation between CO2 and CO.
Which is more stable? How do you know?
Hint: How many electrons does Carbon Need?
Hint: What do atoms do when they don’t have their valence electrons to be stable?
Write down your hypothesis on your paper, make sure to state something about bonding.
What do you think will happen if you breathe in Carbon Monoxide instead of Carbon Dioxide?

15. Experiment & Conclusions
Conclusions:
Why is CO more unstable than CO2?
Carbon does not have its valence shell full.
What does that instability mean for the hemoglobin?
Means that CO will bond to heme more quickly and tightly. But won’t let go to let normal oxygen and CO2 in.
Why are bonding properties of atoms, compounds and molecules important?
Your body needs to get Oxygen to cells and get rid of CO2 properly. If not, the cells and eventually the body will die.