Chemistry Is the Science that deals with the composition, structure, and properties of matter and the transformations which matter undergoes.

The Atom The atom is the building block of all matter. Atom : The smallest particle of an element having the same properties of that element.

Protons  subatomic particles located in the nucleus that have a positive charge. Neutrons  subatomic particles located in the nucleus that have no charge. Electrons  subatomic particles that orbit around the nucleus. They have a negative charge and have relatively no mass as compared to nucleons.

Elements Contain a single type of atom Has properties unique to that element Cannot be broken down into smaller particles easily Organized in table by atomic number, atomic mass, periods, groups or families, metals vs non-metals and metalloids.

The Periodic Table of Elements

Brought to you by…….. Dmitri Mendeleev …a Russian scientist born in Tobolsk, Siberia in 1834, is known as the father of the periodic table of the elements. … The periodic table of the elements: an important tool used by students and chemists to help them understand and simplify the often complex world of chemical reactions. Mendeleev set out to identify a pattern in the elements. The word "periodic" means that there is a repeating pattern -- that is, the properties of the elements repeat with each row -- or period -- of the table.

Horizontal rowsPeriods ( 1-7) Vertical Columns Groups or families ( 1-18)

Find the periodic table in your text on page 570……. Note: Metals appear on the left Non-metals appear on the right Metalloids appear on the “staircase”, the approximate division between metals and nonmetals

Family Names…. Group1:Alkali Metals ( not including hydrogen) react with water to form a basic solution Group 2:Alkaline Earth Metals Groups 3-12: Transition Metals Groups : Representative Element groups Group17: Halogens Group 18: Noble Gases ( highly un-reactive) Lanthanides (removed from period 6 ) and Actinides (elements removed from period 7) Appear at the bottom of the periodic table

Layout of an Element on the Table Elements are presented in the periodic table like this:

From this information, we can determine several different things about an atom of scandium. 21  This is the atomic number of scandium. This number indicates the number of protons in the nucleus of a scandium atom. All atoms of scandium have the same atomic number.

44.96  This is the atomic mass number of scandium. This number, once rounded, indicates the number of protons and neutrons combined in the nucleus of a scandium atom.

Calculating Protons, Neutrons, and Electrons In any atom, we will assume protons and electrons cancel each other out unless a charge is indicated on the element (this will come later). Atomic # = number of protons Mass # = number of protons + neutrons

Another way to write this is: Neutrons = mass # - atomic # Protons = atomic # Electrons = atomic #