1. Chapter 6: Chemistry in Biology

2. Section 1: Atoms, Elements, and Compounds

3. Journal:
This is Biology class, why are we studying chemistry?!

4. Atom- the smallest unit of matter that cannot be broken down by chemical means
ALL matter consists of atoms
What 3 subatomic particles make up atoms?
Particle
Charge
Location
Electron __
Electron cloud
Proton +
Core of nucleus
Neutron o

5. Atom

6. # Protons = # of Electrons So, atoms are electrically neutral

7. Element
Pure substance that cannot be broken down into other substances by physical or chemical means
More than 100 known elements; 92 occur naturally
Each element has a unique name and symbol.

8. Label the groups and periods!
Chemistry in Biology
The Periodic Table of Elements
Horizontal rows are called periods.
Vertical columns are called groups.

9. What are the 6 most common elements of biological organisms?

10. Hydrogen

11. Oxygen

12. Carbon

13. Nitrogen

14. Phosphorus

15. Sulfur

17. 1. What are the symbols for the following elements. Oxygen. Lead
1. What are the symbols for the following elements? Oxygen Lead Calcium
2. How many protons are in the following elements?
Hydrogen Neon Sodium
3. How many electrons are in the following elements?
Carbon Chlorine Iron

18. Answers
1. What are the symbols for the following elements? Oxygen Lead Calcium
O Pb Ca
2. How many protons are in the following elements?
Hydrogen Neon Sodium
3. How many electrons are in the following elements?
Carbon Chlorine Iron

19. Chemistry in Biology
Isotopes
Atoms of the same element that have the same number of protons and electrons but have a different number of neutrons

20. Chemistry in Biology
Radioactive Isotopes
When a nucleus breaks apart, it gives off radiation that can be detected and used for many applications.

21. Chemistry in Biology
Compounds
A pure substance formed when two or more different elements combine
Compounds are always formed from a specific combination of elements in a fixed ratio.
Compounds cannot be broken down into simpler compounds or elements by physical means.

22. Valence Electron
Type of electron available to form chemical bonds

23. Covalent bonds Chemical bond that forms when electrons are shared
Chemistry in Biology
Covalent bonds
Chemical bond that forms when electrons are shared
A molecule is a
compound in which the atoms are held
together by covalent bonds.

24. Chemistry in Biology
Ionic Bonds
Electrical attraction between two oppositely charged atoms or groups of atoms

25. Chemistry in Biology

26. The elements identified as metals tend to donate electrons.
Chemistry in Biology
Some atoms tend to donate or accept electrons more easily than other atoms.
The elements identified as metals tend to donate electrons.
The elements identified as nonmetals tend to accept electrons.

27. Bonding Analogies
Try to come up with analogies to explain the behavior of electrons in both ionic and covalent bonds.

28. Chemistry in Biology
van der Waals Forces
When molecules come close together, the attractive forces between slightly positive and negative regions pull on the molecules and hold them together.
The strength of the attraction depends on the size of the molecule, its shape, and its ability to attract electrons.

29. van der Waals Forces
Not as strong as ionic or covalent bonds, but play a key role in biological processes!

30. Opposites Attract

31. Demo
Element or Compound?

32. Let’s look at an example
Let’s look at an example. The element sodium is a silver-colored metal that reacts so violently with water that flames are produced when sodium gets wet. The element chlorine is a greenish-colored gas that is so poisonous that it was used as a weapon in World War I.
When chemically bonded together, these two dangerous substances form the compound sodium chloride, a compound so safe that we eat it every day. What is the compound?
Common Table Salt!!
Sodium metal, Na + Chlorine gas, Cl = Table Salt, NaCl

33. A Real Bonding Experience…
As a group, you will be assigned various elements.
Determine the atomic number, atomic mass, protons, neutrons, electrons for each element.
Construct Bohr Diagrams and Lewis Structures for your element.
Form the Lewis structure, using your group members as electrons.
Determine which other elements in the class you are likely to bond with, and decide whether it will be an ionic or covalent bond.
Act out the formation of the bond.