Elements *organized on the Periodic Table of Elements *periodic= occuring in a predictable pattern

The Ancient Beliefs 440 BC They thought there were 4 elements: Fire Water Wind Earth

Elements are substances that cannot be changed into simpler substances by chemical reactions. There are about 118 elements found on Earth (only 92 occur naturally).

Starts with metals

Metals-  Metalloids--  Nonmetals-  Noble Gases

An atom is the smallest part of an element An atom is made up of: Protons Neutrons Electrons

Key for the Periodic Table C Carbon Element name atomic number Element symbol atomic mass

Subatomic particles particlechargelocationMass (in amu’s) Proton+In nucleus1 neutronNo chargeIn nucleus1 electronnegativeIn orbit around the nucleus 1/1836

Video on atoms-listen

An atom of Lithium *The atomic # of Lithium must be 3 *The mass of an atom of Lithium MUST be 7. (4+3)

An atom of Sodium Na The atomic # of Sodium must be 11 *The mass of an atom of Lithium MUST be 23. ( )

The atom and the Periodic Table The atomic # = the # of protons The mass of the atom is: (# protons) + (# of neutrons) Assume the # of electrons = # protons

Drawing atoms: Let’s draw an atom of: Carbon Let’s draw an atom of: Fluorine

Atom comes from the Greek word atomos Atomos in Greek means INVISIBLE Scientists used to think that the atom was NOT made of any smaller particles It wasn’t until 1897 that scientists realized that atoms are made up of smaller particles

Draw these on your own Helium Potassium Oxygen Hydrogen

Molecules and atoms Molecules are made up of atoms. Water is a molecule with 2 Hydrogen atoms and and 1 Oxygen atom. How many atoms are in: CO 2 H 2 O 2 O 2

What are they? Metals Good conductors of heat and electricity Good at giving up electrons Malleable and ductile Lustrous Non-Metals Poor conductors therefore, good insulators Good at taking electrons Brittle (break easily)

Nuclei of a Helium atom and of a Lithium atom