1. Biochemistry Part 2
Bonding, Isotopes, and Radioactivity

2. Recap
Atomic structure
Valence electrons
Happy atoms are full atoms (8 ve or 2 ve)
How do we make them happy???
STEALING or SHARING valence shell electrons to have a complete ringremember the Samaras?
3. 4. Ionic Bonds
Atoms become IONS by losing or gaining electrons
What is the charge of an electron?
Sooothey are losing or gaining a NEGATIVE charge
Covalent Bonds
SHARING of electrons
Val. Electrons spend their time around both atoms involved in the bond
NOT always equally shared, but still shared
Two Types of Bonds
5. Ionic Compounds
Ions
A POSITIVELY or NEGATIVELY charged particle
Formed by gaining or losing electrons in an effort to become stable
Atom that lose one or more electron(s) POSITIVELY charged..CA+IONS
Atom that gains one or more electron(s)ANIONS
STEALING e-
6. Which atoms become ions?
Which ever are veryyyyy close to being happy
They either have to lose or gain one or two electrons to have a complete outer ring
Remember, atoms are LAZY, they want to do as little work as possible to be happy
Groups 1A and 2A will lose e- and become +1 or +2 ca+ions (+)
Groups 6A and 7A greedy little suckers that will steal e- to become -1 or -2 anions (-)
7. 8. Formation of Ionic Compounds
Opposites attractpositive ion finds an equally negative ion and they are hooked! (bonded)..its an IONIC BOND!!!

Charges cancel out and now we have a neutral (zero charge) Ionic Compound

When naming Ionic Compounds
Say the ca+ion first, then the anion
Add the suffix ide to the anion
Ex. Sodium and chlorine form
Na+ and Cl-
You say Sodium chloride
9. Covalent Compounds
Not greedythey would rather share
Their outer rings are about half way full
Groups 3,4 and 5
The # of bonds an atom can form is equal to the number of valence electrons it NEEDS to be happy
Oxygen has___v.e.it needs___to be happy, so it can make ____ bonds.
10. Covalent Bonds make
2 or More atoms covalently bonded make a compound called a MOLECULE
Sharing of 2 e- b/t 2 atoms single bond (pretty strong)
Sharing of 4 e- b/t 2 atoms double bond (stronger hold)
Sharing of 6 e- b/t 2 atoms triple bond (really strong!)
11. 12. 7 Diatomic Molecules
Di- means..
2
Atomic means
Referring to atoms
Molecules
Covalently bonded atoms
Put it together and what do you get:
2 atoms of the same element that are covalently bonded to EACHOTHER
Occurs naturally in Nature
Br2 I2 N2 Cl2H2O2 F2
BrINClHOF!!!
13. Recap
When we change # of protons we get
A different element
We dont want to change this!
When we change # of electrons we get
IONS!
Cations + LOSE an electron
Anions Gain an electron
When we change the # of neutrons we get
14. ISOTOPES!
Atoms with the same atomic number but with different atomic masses are called isotopes
Changing the # of neutrons in an atom will affect the
MASS NUMBER= protons + neutrons
Isotopes of an element have the same # of p+ and e-so they behave the same CHEMICALLY
The average of all the mass #s of the isotopes of an element give us that decimal on the periodic table (Average Atomic Mass)
15. 16. 17. Radioactive Isotopes
As the difference b/t p+ and n. in the nucleus increases, the nucleus becomes more unstable
When p=n , nucleus is stable
When n>p, nucleus is unstable
Nucleus will give off tiny amounts of energy to become stable (protons or neutrons)
Radiation=energy
Radioactive=when something gives off energy
18. Isotopes of the Element Potassium with a Known Natural Abundance
Mass #Natural AbundanceHalf-life
39 93.2581% Stable
40 0.0117% 1.26510+9 years
41 6.7302% Stable
19. Isotopes continued
Radiation can be dangerous in large amounts but in small amounts it can be useful in science
Geology-determine age of fossils and rocks
Medicine-treat cancer and detect cell processes (tracers)
PET scans, CT scans, MRI
Commercial-kill bacteria that spoils certain foods
20. Mm Isotope Discovery Lab
21. New Discovery!!!
You and your research team have discovered a new elementMm
Mm is an essential element in the human diet
There are three naturally occurring isotopes of the element Mm
Atomic Number of Mm is 30
Your teams goal is to determine the average atomic mass of the element Mm by determining the percent abundance of each naturally occurring Mm isotope
You have already determined the masses of each of the three different Mm isotopes:
22. Calculations
Percent Abundance of isotope Mm-R=
(Total # of Mm-R in nature/ Total # of all Mm-isotopes in nature) x 100%
Percent Abundance of isotope Mm-B=
(Total # of Mm-B in nature/ Total # of all Mm-isotopes in nature) x 100%
Percent Abundance of isotope Mm-Y=
(Total # of Mm-Y in nature/ Total # of all Mm-isotopes in nature) x 100%
Mass Contribution of each isotope:
(amu of Mm isotope) x (percent abundance of Mm isotope in nature)
Average Atomic Mass=
[(mass contribution of Mm-R) + (mass contr. of Mm-B) + (mass contr. of Mm-Y)]
Show ALL Calculations
Take Pictures of Set up
Record all procedures
23. Homework
Complete Lab Report For Isotope Lab
See lab report guidelines
Extra Credit:
Make A Creative Periodic Table Element Box for your New Element.Be sure to include all your information you gathered from your extensive research!
Atomic Number
Average Atomic Mass
Chemical Symbol
BE CREATIVE!