Principles of Matter and Energy

Outline I What is Matter III Types of Bonds A. ElementsA. Ionic B. Compounds B. Covalent II Atoms IV Chemical Reactions A. Components B. Ions C. Isotopes D. Energy

What is Matter? Matter: Unit of matter is the atom Matter consists of elements which are combined to form molecules and compounds

Elements Exs: H hydrogen, O oxygen, He helium, Ca calcium, Au gold

Compounds Molecule:

Components of Atoms Atom:

Components of Atoms Made up of three types of particles: – Protons: – Neutrons: – Electrons:

Ions Usually #protons = #electrons – Atom has no net charge = neutral Ion: – Cation: – Anion:

Isotopes Atoms of the same element that differ in atomic mass Examples:

Isotopes Radioactive isotopes: nucleus decays spontaneously releasing high-energy electromagnetic radiation, subatomic particles, or both

Isotopes Half-life: Example: Tritium ( 3 H) decays into 3 He with a half-life of 12.5 years Some isotopes have very short half-lives (e.g. iodine) while others are extremely long (e.g. plutonium, a waste product of nuclear power reactions, has a half-life of 24,000 years.

Isotopes – By determining ratios of the different isotopes of carbon and other elements in samples of biological origin and in rocks, scientists are able to determine with certainty when these materials formed. Half-life cannot be changed by temperature, pressure, chemical reactions, or any other environmental factor. – Another use of isotopes is in medicine-tracking physiological processes. E.g. isotope of iodine used to check for thyroid problems

Energy Within the Atom

Chemical Bonding Chemical Bond:

Ionic Bonds Example:

Covalent Bonds Electronegativity:

Non-polar Covalent Bonds Examples

Polar Covalent Bonds Examples

Hydrogen Bonds Example

Molecular Shape and Function Examples

Chemical Reactions