THE CHEMICAL CONTEXT OF LIFE

Key Concepts  Matter Consists of chemical elements in pure form and in combinations called compounds.  An elements properties depend on the structure of its atoms.  The formation and function of molecules depend on chemical bonding between atoms  Chemical reactions make and break chemical bonds.

Elements & Compounds  Organisms are made up of matter.  Matter is anything that takes up space and has mass.  Matter is made up of elements.  Elements are substances that cannot be broken down to other substances by chemical reactions.  There are about 92 natural elements recognized by chemists today. 

Elements & Compounds  A Compound is a substance consisting of 2 or more different elements combined in a fixed ratio.  NaCl table salt (1:1 ratio) is edible.  Pure Sodium (Na) is a metal  Chlorine (Cl) is a toxic gas  A compound has characteristics different from those of its elements

Essential Elements of Life  25 elements are known to be essential to life.  4 of these elements make up 96% of all living matter.  Carbon – (C)  Oxygen – (O)  Hydrogen – (H)  Nitrogen – (N) 

Essential Elements of Life  Potassium, Sulfur, Calcium, Phosphorous and a few others account for the other 4%  Trace Elements – required by organisms in minute quantities  Some trace elements such as iron (Fe) are needed for all forms of life. Others are needed only by certain species.

Trace Elements  Nitrogen Deficiency

Trace Elements  Iodine deficiency

Elements  Each element consists of a certain kind of atom that is different from the atoms of any other element.  Atom – smallest unit of matter that retains the properties of the element.

Subatomic Particles  Atoms are composed of smaller parts called subatomic particles.  Neutrons  Protons  Electrons

 Neutrons and Protons are found in the center of the atom, the atomic nucleus.

 Electrons – move at almost the speed of light form a cloud around the nucleus.

 Electrons have a negative charge  Protons have a positive charge  Neutrons are electrically neutral

Atomic Number

Atomic Mass

Isotopes

Radioisotopes Madame Marie Curie Irene Joliot- Curie

Radioactive Isotopes  A medical isotope is a very small amount of radioactive material used to perform nuclear medicine imaging tests. Different formulations of isotopes are injected into patients, where they give off energy that is read by special cameras. They are crucial to helping doctors diagnose major diseases like heart disease and cancer.

Radioisotopes in Medicine

PET Scan

Cancer Treatments Radiation therapy uses high energy x-rays to kill or shrink cancer cells. The radiation may come from outside the body or from radioactive materials placed directly into or near the tumor.