1. Honors Biology Chapter 2
The Chemistry Of
life

2. The Nature of Matter
Essential Question:
How would you explain the relationship between atoms, elements, and compounds?

3. Atoms smallest unit of matter
each element has its own unique # of protons
(atomic #)

4. Elements Only ~ 24 elements found in living things 4 most abundant:
Oxygen
Carbon
Hydrogen
Nitrogen

5. Isotopes atoms of same element with different # of neutrons
#p + #n = atomic mass
(mass #)

6. Radioactive Isotopes
some isotopes have unstable nuclei so they undergo “decay”

7. Chemical Cpds
compound: substance formed by chemical combination of 2 or more elements in definite proportions
cpd has different properties than elements alone had

8. Chemical Formulas

9. Chemical Bonds
Atoms form chemical bonds with other atoms to ________________.
The 2 main types of bonds are ________ and ____________.

10. Types of Bonds

11. Chemical Bonds share valence e- unequal sharing e- Covalent Bonds
Polar Covalent Bonds
share valence e-
unequal sharing e-

12. Ionic bonds transfer of e-  atom with a charge (ion)
(+) ions = cations
(-) ions = anions
opposite charges attract
charges must be balanced
stronger bonds than covalent

13. van der Waals Forces
Because atoms do not share e- equally, there are polar bonds
This causes the (+) end of one molecule to be attracted to the (-) end of another molecule
This attraction is called van der waals forces
Very weak compared to covalent bonds but are still able to hold molecules together

14. Van der Waals Forces in action

15. What type of bond is shown here?