Biology = Chemistry
What do you know?
• What is matter?• What is an element?• What is pH?• What is a subatomic particle? Name them.• Sodium is an explosive metal, chlorine is a toxic gas.
What do you get when they are combined?• What is the building block of life? Why?• What is a polymer?
Atoms and Elements
• What is an atom?• -the smallest unit of an
element defined by its number of subatomic particles
• Subatomic Particles
Proton Neutron Electron
Symbol p+ n e-
Charge +1 0 -1
Elements
• Made entirely of 1 type of atom• Defined by number of protons in the atoms
# protons = Atomic Number of the element, determines place on the periodic table
• Number of protons = number of electrons (why would this be?)
Isotopes
• Electrons determine chemical properities
• Two atoms of the same element with different numbers of neutrons are isotopes
Example: Carbon 12, 13 and 14
Compounds
• Two or more elements together = compound• Can have greatly different properties from the
elements that make them
Example: Dihydrogen monoxide
O2= reactive gas
H2= explosive gas
2H2 + O2 2H2O
• Example 2 Sodium chloride (table salt)
Na (sodium) = explosive metal
Cl2 (chlorine gas) = toxic (mustard) gas
2Na (element) + Cl2 (element) = NaCl (compound)
Chemical Bonding
• General Rule (usually true, not always) : Atoms want 8 valence electrons look like a noble gas
• Ionic Bonds
- 1 or more electrons are transferred from one atom to another
- Creates charged atoms or ions
- Ions are strongly attracted to each other like a balloon and static
- Example : Formation of NaCl
• Covalent Bonding
- Instead of swapping, atoms share electrons to form compounds
- Still form octets but through shared electrons
- Example : formation of water
Strength of Bonds (StrongestWeakest)
• 1. Covalent• 2. Ionic• 3. Hydrogen• 4. Van der Waals forces