1. The Chemistry of Life Domains of Study Domain of BioMolecules
Domain of Cells
Domain of Organisms
Domain of Populations
Domain of Communities

2. Everything is made of matter Matter is made of atoms
Hydrogen
1 proton
1 electron
Oxygen
8 protons
8 neutrons
8 electrons
Proton +
Neutron
Electron –

3. Different kinds of atoms = elements
The World of Elements H C N O Na Mg P S K Ca
Different kinds of atoms = elements

4. atoms
Atomic # = number of protons Atomic Mass = protons + neutrons How do you figure out how many neutrons in an atom? Electrons?

5. ??? Practice N 7 14 B 5 11 H 1 C 6 12 Symbol Atomic number Mass number
Protons
Neutrons
electrons N 7 14 B 5 11 H 1 C 6 12
???

6. Isotopes! Same element Different number of neutrons
Mass number relates to the particular isotope
C14 and C12

7. Medical uses for radioactive isotopes
A PET scan is one of the many medical uses for radioactive isotopes
PET, short for positron-emission tomography, can detect intense chemical activity in the body. Brightly colored areas indicate elevated levels of radioactively-labeled glucose and high metabolic activity, which is a strong indicator of cancerous tissue.

8. Bonding properties Effect of electrons
What’s the magic number?
Bonding properties
Effect of electrons
chemical behavior of an atom depends on number of electrons in its valence shell
Sulfur on the LEFT
Magnesium on the RIGHT
How does this atom behave?
How does this atom behave?

9. This tendency drives chemical reactions…
Chemical reactivity
Atoms tend to
complete a partially filled valence shell or
empty a partially filled valence shell
This tendency drives chemical reactions…
and creates bonds – –

10. Bonds in Biology Covalent Bonds: atoms share electrons (strong)
Hydrogen bond
Bonds in Biology
H2O
Covalent Bonds: atoms share electrons (strong)
Ionic bonds: give/take electrons and oposites attract
Van der Waals forces
Hydrogen Bonds!!
H2O
Covalent bond –
H2 (hydrogen gas)

11. Letters are used to represent the elements
Chemical Formula
A chemical formula shows the kinds and number of atoms in a substance.
Letters are used to represent the elements 3H O
Number of molecules 2
Subscript is used to represent the # of each element (for example 2 Hydrogens) ones are assumed

12. Covalent bonds Why are covalent bonds strong bonds? Forms molecules
two atoms share a pair of electrons
both atoms holding onto the electrons
very stable
Forms molecules H
Oxygen – H O
H — H
H2 (hydrogen gas)
H2O (water)

13. Multiple covalent bonds
2 atoms can share >1 pair of electrons
double bonds
2 pairs of electrons
triple bonds
3 pairs of electrons
Very strong bonds
More is better! H
H–C–H –

14. Nonpolar covalent bond
Pair of electrons shared equally by 2 atoms
example: hydrocarbons = CxHx
methane (CH4 )
balanced, stable, good building block

15. Polar covalent bonds Pair of electrons shared unequally by 2 atoms
example: water = H2O
oxygen has stronger “attraction” for the electrons than hydrogen
oxygen has higher electronegativity
water is a polar molecule
+ vs – poles
leads to many interesting properties of water… H
Oxygen + – – – – +

16. Ionic Bonds Electrons are transferred from one atom to the other making them charged ions. Opposites attract

17. All compounds have properties that are different from the elements that make them. These are called Emergent Properties

18. Emergent properties +

19. CHEMICAL REACTIONS: energy + 6CO2 + 6H2O  C6H12O6 + 6O2
Describe the process in which elements react to form new compounds.
Result in the release or absorption of energy.
Ex. What does this chemical equation represent?
energy + 6CO2 + 6H2O  C6H12O6 + 6O2
Sunlight + 6 carbon dioxide + 6 water molecules reacts to form glucose + 6 oxygen gas molecules

20. Any Questions? Do one brave thing today…then run like hell!
He’s gonna earn a Darwin Award!
Any Questions?
Do one brave thing today…then run like hell!