1. Building a “Cereal” Atom

2. Two Minutes… http://timer.onlineclock.net/
What do you already know about atoms?

3. Atoms Building blocks of matter What is matter?
Atoms are made up of subatomic particles: protons, neutrons, & electrons.
Atoms have a dense, heavy nucleus surrounded by electron shells.

4. Subatomic Particles Protons Have a positive charge
Located in the nucleus
Weigh 1 amu (atomic mass unit)

5. Subatomic Particles Neutrons Are neutral with a charge of 0
Located in the nucleus
Weigh 1 amu

6. Subatomic Particles Electrons Have a negative charge (1 e = -1)
Located in an electron cloud surrounding the nucleus
Electron cloud is actually made up of energy levels
Weigh 5.5 x10-4 amu = amu

7. Electron Energy Levels
Level 1 holds 2 e-
Level 2 holds 8 e-
Level 3 holds 18 e-
Level 4 holds 32 e-
Draw a picture on your notes!

8. Create a Cereal Atom
2 minutes…

10. Element
Pure substance that can’t be broken down into any other substances physically or chemically
Made up of only one type of atom
Each element has a specific, unique atomic number, name, and symbol
Carbon’s atomic number is always 6 and no other element can have this number!
Symbol for Carbon = C

11. Atomic Number (Z) Number of protons in the nucleus of an atom
Defines an element
Each element has their own atomic number

12. Mass Number (A)
The total number of protons and neutrons in the nucleus of an atom
Find the number of neutrons if you are told an element has an atomic number (Z) of 29 and a mass number (A) of 63?
What is this element?
Neutrons = A - Z

13. Build your atom!
Choose an element with your partner and create an atom of that particular element with the correct number of p+, n, and e-.
Place a notecard next to your atom with the element symbol, atomic number, and mass number.

14. Isotope
Forms of the same element that have the same number of proton and electrons but a different number of neutrons
This does not change the atom’s charge
Ex:
C12, C13, C14 are all Carbon isotopes

15. Valence Electrons
Electrons found in the outermost electron shell of an atom
The number of valence electrons can be determined by the columns on the periodic table
*Let’s label our periodic tables!
Valence electrons determine how (and whether) the atom will react with other atoms

16. Why are some atoms very reactive while others are more stable?
Octet rule- atoms are more stable when their outer electron shells are full, thus some atoms will readily react to lose or gain electrons to fulfill the octet rule
They are stable when they have the maximum number of valence electrons in their outer shell
Examples: Helium, Sodium, & Fluorine

17. Atom Stability
Atoms are most stable when their outmost energy level is completely filled
If it is not, atoms can donate or accept electrons to fill their out energy level to become more stable
Would Sodium (Na) want to donate or accept an electron?
How about Calcium (Ca)?

18. Ion An atom that has lost of gained one or more electrons
Has an electric charge
A positive ion = cation
A negative ion = anion

19. Sodium Ion

20. Ionic Bond
Occurs when 2 oppositely charged ions attract each other and from a compound
Example: NaCl (sodium chloride)

21. How does this relate to Carbon?
Why doesn’t Carbon ever form ions?
Carbon has 4 valence electrons, so it would take a lot of work to add 4 or lose 4 electrons
Instead carbon shares 4 electrons with other atoms
Covalent bond- when 2 atoms share electrons

22. All living things are made up of carbon!
What is the importance of Carbon’s stability in biological systems?
Carbon can bond with other atoms in a large number of different ways, making a huge variety of large complex molecules that make up all living organisms
Carbon mainly bonds to other carbon atoms, oxygen, hydrogen, and nitrogen