1. the dirty little secret about Biology
Chemistry
the dirty little secret about Biology

2. (wait, isn’t that Biology?)
Chemistry
Chemicals are the stuff that make up
our bodies,
the bodies of other organisms, and
the physical environment.
(wait, isn’t that Biology?)
© 2012 Pearson Education, Inc.

3. Water Life’s chemistry is tied to water. Life first evolved in water.
All living organisms require water.
The chemical reactions of your body occur in cells consisting of 70–95% water.
© 2012 Pearson Education, Inc.

4. Matter anything that occupies space and has mass composed of elements
cannot be broken down into other substances
92 in nature; scientists have created 26 more
created elements too unstable to occur naturally
you ARE chemistry
chemistry is your friend!
© 2012 Pearson Education, Inc.

5. Atoms
smallest unit of matter that still retains properties of that element (fxnal unit of matter)
nucleus
protons (positive charge)
neutrons (no charge)
orbital shell
electrons (negative charge and hardly any weight)
opposites attract
© 2012 Pearson Education, Inc.

6. Helium Nucleus 2e Electron cloud 2 Protons Mass number  4 Neutrons
Figure 2.3A
Helium
Nucleus
Electron cloud 2
Protons
Neutrons
Electrons
Mass number  4
2e
Figure 2.3A Two models of a helium atom 6

8. http://www. google. com/imgres. imgurl=http://www. classzone

10. Carbon Electron cloud 6e Nucleus 6 Protons Mass number  12 6
Figure 2.3B
Carbon
Electron cloud
6e
Nucleus
Figure 2.3B Model of a carbon atom 6
Protons
Mass number  12 6
Neutrons 6
Electrons 10

13. http://terra. dadeschools

14. Isotopes: Medical Uses
Living cells cannot distinguish between isotopes of the same element.
Therefore, radioactive compounds in metabolic processes can act as tracers.
This radioactivity can be detected by instruments.
Using these instruments, the fate of radioactive tracers can be monitored in living organisms.
© 2012 Pearson Education, Inc.

15. Figure 5.3 Radioisotopes Are Useful in Medical Imaging
(a) The thyroid gland, located in the neck, helps regulate metabolism. The element iodine accumulates in the gland and is necessary for normal thyroid function. (b) This image is a visualization of the thyroid gland in a patient with goiter, an enlargement of the thyroid gland, often caused by iodine deficiency. Small amounts of radioactive iodine were given to the patient, and the accumulated radioisotope was visualized with a gamma-ray scan.

17. Chemical Bonds electrons: the only part of an atom that interact
arranged in shells around the nucleus
have one, two or three electron shells
have to fill the 1st shell
then get a 2nd shell
have to fill the 2nd shell,
then get a 3rd shell
© 2012 Pearson Education, Inc.

18. Chemical Bonds # of shells determined by # of protons
Figure 2.5_1
Chemical Bonds
Hydrogen
Helium
Lithium
Beryllium
Boron
Carbon
Nitrogen
Oxygen
Fluorine
Neon
Sodium
Magnesium
Aluminum
Silicon
Phosphorus
Sulfur
Chlorine
Argon
Figure 2.5_1 The electron distribution diagrams of the first 18 elements in the periodic table
# of shells determined by # of protons
atoms want the outermost shell to be filled
=STABILITY 18

19. Sodium Chlorine Sodium chloride Figure 2.1
Figure 2.1 The emergent properties of the edible compound sodium chloride
Sodium
Chlorine
Sodium chloride 19

20. Chemical Bonds: 3 Types Ionic: gaining or losing of electrons
NaCl excellent example
Na+ has 1 e- in its outer shell
(how many needed to be stable?)
Cl- has 7 e- in its outer shell

22. Figure 5.6 Ions Are Created through the Loss or Gain of Electrons
Negatively charged ions are often given special names, such as “chloride” for the chlorine ion (Cl−) and “fluoride” for the fluorine ion (F−).

23. Na Sodium atom Cl Chlorine atom Na Sodium ion Cl Chloride ion
Figure 2.7A_s2
Transfer of electron
Na Sodium atom
Cl Chlorine atom
Na Sodium ion
Cl Chloride ion
Figure 2.7A_s2 Formation of an ionic bond, producing sodium chloride (step 2)
Sodium chloride (NaCl) 23

24. Now both Na+ and Cl- have filled their outer shells
= STABILITY!!!
they are ALSO both charged now b/c they have an electron/proton imbalance

25. Ionic Bonds: opposites attract
WEAK: toss in water and dissolve-why?

26. WATER is POLAR!!!!

27. Ionic Bonds Synonyms: Similar to ‘dating’ Ca++ means what?
salt
electrolyte
Similar to ‘dating’
Ca++ means what?
PO43- means what?

28. Covalent Bonds
e- are shared: they orbit around nuclei of both atoms involved in the bond
very strong bond:
takes NRG to create
releases NRG when broken
MARRIAGE!!!

31. Covalent Bonds all compounds are molecules,
two or more atoms joined together
= Molecule
two or more types of atoms joined together
= Compound
all compounds are molecules,
BUT not all molecules are compounds

32. Table 2.6
Table 2.6 Alternative ways to represent four common molecules 32

33. nonpolar: equal sharing of e-
nonpolar: equal sharing of e-

34. Figure 2-5 Polar Covalent Bonds and the Structure of Water
Hydrogen
atom
Oxygen atom
2 
Polar: UNequal sharing of e-
due to difference in pull from nucleus
© 2012 Pearson Education, Inc. 34

35. Hydrogen Bonds: weak but IMPORTANT!!!

36. Chemical Reactions Interactions between atoms
making bonds (stores NRG)
breaking bonds (releases NRG)
chemical rxns do not create or destroy matter
rearrange matter
rxns of life generally require enzymes
NRG not created or destroyed