Transcript Old Lesson 2-1. Use this one!

The Chemical Basis of Life
Objectives:
• Explain the relationship between
elements, compounds, atoms, and
molecules
• List the major elements and major
minerals
• Discuss atomic structure and explain
how an atom’s electron shells influence
its ability to enter into chemical
reactions
Objectives
• Compare and Contrast the three major
types of chemical bonds
• List and describe the three basic types
of chemical reactions that occur in living
material
Terms
• Biochemistry- chemistry that deals
with living organisms
• Matter- anything that occupies
space and has mass
• Elements- can’t be broken down
into tow or more different
substances
–EX: O2
Terms
• Compound- two or more elements
together
–EX: CO2 or NaCl
• Major elements- make up a large
portion of our body
• Trace elements- are present in the
body in small amounts
Chemical Symbols
•
•
•
•
•
•
O- oxygen
C- carbon
H- Hydrogen
N- Nitrogen
Ca- Calcium
P- Phosphorus
•
•
•
•
•
•
K- Potassium
S- Sulfur
Na- Sodium
Cl- Clorine
Fe- Iron
I- Iodine
Atoms
• basic building block of all things
• can be broken down into subatomic
particles
Atomic Structure
• Protons
–positive
–found in the nucleus
• Neutrons
–neutral
–found in the nucleus
Atomic Structure
• Electrons
–negative
–found in the electron shell
Atomic Number and Weight
• Atomic number- the number of protons
in a nucleus
• Atomic weight- mass of an atom
– only the nucleus has weight
– equals the number of protons and
neutrons
Electron Shells
• The number of electrons equals the
number of protons
• use the Bohr model to visualize
electrons
Bohr Model
• Each ring is
different energy
level
• First shell holds two
• Second shell holds
8
• If outer shell is full,
the atom won’t form
bonds
Bohr Model
• Rule of Octet- says the outer shell can
hold eight electrons
Isotopes
• All atoms of the same element have the
same number of protons
• They do not contain the same number
of neutrons and these are called
isotopes
• Ex: Most carbon has 6 electrons but
carbon 14 has 8
– atomic weight of 14
Chemical Bonds
• Molecule- any two or more atoms
coming together
– N2
• Compound- two or more different atoms
come together
– NaCl
Ionic or Electrovalent Bonds
• Forms by the transfer of electrons
• occurs as a result of electrically charged
atoms called ions
Ionic Bonds
Na needs to lose one, Cl needs to gain
one
Covalent Bonds
Shares Electrons
Hydrogen Bond
• Form due to unequal charge
• no electrons are shared or
transferred
• Water is a hydrogen bond
• Are very weak
• Allows water to change states
Chemical Reactions
• Synthesis- putting things together
– A + B = AB
• Decomposition- take things apart
– AB= A + B
• Exchange
– AB + CD = AC + BD