2A.1 & 2A.2 Atoms and Elements 9/18/2017

Atom The basic building block for all matter in the universe. Atoms fit together with other atoms to form matter. Atoms make up all matter in the universe.

Atom Each atom is composed of 3 subatomic particles: Protons Neutrons Electrons The number of each atomic particle determines the properties of the atom.

Proton Positively charged Has the same mass as Neutrons Located in the nucleus; tightly bound to neutrons

Neutron Has no charge (neutral) Has the same mass as Protons Located in the nucleus; tightly bound to protons

Neutron Has no charge (neutral) Has the same mass as Protons Located in the nucleus; tightly bound to protons

Electron Negatively charged Rotate in the space around the nucleus

History of the Atomic Model 1st Discovery: Democritus-Came up with the name atom; determined that atoms can not be divided.

History of the Atomic Model 2nd Discovery: Dalton-Theorized atoms are too small to be seen by the naked eye; came up with the Atomic Theory of Matter

History of the Atomic Model 3rd Discovery: Thompson-Used cathode ray to detect electrons and theorized that electrons were embedded in nuclei of atoms (Chocolate Chip Model)

History of the Atomic Model 4th Discovery: Rutherford-Theorized that atoms had a dense core which was a positive nucleus

History of the Atomic Model 5th Discovery: Bohr-Theorized electrons were orbiting the nucleus

Element A substance whose elements all have the same number of protons in the nucleus.

Periodic Table Used to organize all elements Every element has a square for each element that includes: Element Name Chemical/Element Symbol Atomic Number Atomic Mass

Element Name

Chemical/Element Symbol Element Name Chemical/Element Symbol

Chemical/Element Symbol Each element has a different symbol Symbols are written with one, two, or three letters The first letter is always capitalized

Chemical/Element Symbol Element Name Atomic Number Chemical/Element Symbol

Atomic Number The atomic number of an element is equal to the number of protons that element’s atoms have. The atomic number is a whole number The atomic number is always the same for that element. The elements on the periodic table are arranged numerically by increasing atomic number.

Chemical/Element Symbol Element Name Atomic Number Chemical/Element Symbol Atomic Mass

Atomic Mass The atomic mass of an element is an average sum of the number of protons and the number of neutrons in the nucleus of an atom. Atomic Mass is usually not a whole number.

Periods Families A horizontal row on the periodic table. Vertical columns of elements on the periodic table. They are numbered 1-18 Elements in the same family have similar properties Also called Groups

Metalloids Elements that have properties of both a metal and a nonmetal

Metals Majority of elements are metals. Look back at your notes for the physical an chemical properties of notes.

Nonmetals