1. Chemistry for the Biologist

2. Structure of Matter
Matter – anything that takes up space and has mass; composed of elements
Elements – composed of chemically identical atoms
Atoms – smallest particle of an element that still behaves like the element

3. Molecules and Compounds
Molecules – particle formed when two or more atoms chemically combine
Compound – particle formed when two or more atoms of different elements chemically combine
Molecular formulas – depict the elements present and the number of each atom present in the molecule
H C6H12O H2O
2-7

4. What does a formula say? Example CaCO3 1 calcium atom (one understood)
1 carbon atom (one understood)
3 oxygen atoms (3 subscript)

5. Structural Formula
Structural formulas show how atoms bond and are arranged in various molecules

6. Bulk Elements 97% of the elements in living things
- Are the main elements of life
97% of the elements in living things
Sulfur
Phosphorus
Oxygen
Nitrogen
Carbon
Hydrogen

7. Trace Elements
20 elements that are found in small amounts Play important roles in the body’s processes I Iodine, Zn Zinc, Cu Copper, F Fluorine, Mg Magnesium, Na Sodium , Ca Calcium, K Potassium,Fe Iron .

8. Iodine Defiency-Goiter
For example, in vertebrates (animals with backbones) the element iodine is necessary ingredient of hormone production by the thyroid gland. A daily intake of .15 milligrams of iodine is adequate for normal activity of the human thyroid, but an iodine deficiency in the diet causes the thyroid gland to grow to abnormal size, producing a deformity called a goiter

9. The Atom

10. Nucleus -Center of the Atom
Contains the mass of the atom
Protons (p+) which are positive particles
1 proton = 1 AMU (Atomic Mass Unit)
Neutrons (no) which are neutral particles
1 neutron = 1 AMU

11. Surrounding the Nucleus
Electrons (e-) which are negative particles orbit outside of the nucleus
- electrons have so little mass that it isn’t measured

12. Information About an Atom
Atomic Number –
Represents the # of protons in an element
Determines the element
and its properties
#protons + = #electrons -
What is overall charge on an atom?

13. Mass Number Sum of all protons & neutrons in an atom’s nucleus
Example – Sodium (Na)
mass number = 23
atomic number = 11.
How many protons?
How many neutrons?
How many electrons?

14. Isotope
atoms of an element w/the same # of p+ but a different # of no.
It changes the atomic mass
C12 = 6 p+, 6 n0, 6 e AMU
C13 = 6 p+, 7 n0, 6 e AMU
C14 =? _?_ AMU

15. Radioactive Isotopes Some isotopes are unstable and decay over time
Breakdown and release radioactive particles and energy as radiation to become stable form of another element
Ex = C14 becomes N14
Biological uses of Radioactive Isotopes
- carbon dating – find the age of bio material
- molecular tracers – used to trace reactions in living things
- nuclear medicine – imaging and cancer treatment

16. Ion Charged Atom – Atoms can gain or lose electrons to become charged
Anion - an element which gains electrons giving it more electrons than protons
anions have a ________?__________charge
Cation - an element loses electrons, giving it more protons than electrons
cations have a __________?________ charge

17. Valence Electrons Electrons that are found on the outer most orbital.
An atom can have
2e- first orbital
8 e- second orbital
8 e- third orbital
The octet rule
- Atoms are most stable with 8 valence electron

18. Valence Electrons –Octet Rule
The Octet Rule - Atoms are most stable with valence electrons
- To become stable, atoms can:
give away electrons to other atoms
accept electrons from other atoms
share electrons with other atoms

19. Valence Electrons Chlorine has 17 electrons 2 in the first orbital
8 in the second orbital
7 in the third orbital
How many valence electrons does it have?
How many more does it need to be stable?
Should it gain or lose electrons?
What is its ionic charge?

20. Valence Electrons Sodium has 11 e- 2 e- in the first orbital
8 e- in the second orbital
1 e- in the third orbital
How many valence electrons does it have?
How many valence electrons does it need?
Is it easier to gain 7 or lose 1?
What is sodium’s ionic charge?

21. Valence Rules
Atoms with 1,2 or 3 valence electrons usually give away electrons and become positive ions (cations)
Atoms with 4 valence electrons can either give away or gain electrons
Atoms with 5,6, or 7 valence electrons usually gain
electrons and become negative ions (anions)

22. Vocabulary Atom, Nucleus, Proton, Neutron,Electron Atomic Number
Mass Number
Isotopes, Ions, Cations, Anions
Valence Electrons