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

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 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