What you need to know for your Chemistry Test
Atoms models:
Dalton- Billiard Ball Model
J.J. Thompson- Plum Pudding Model
Rutherford- Jimmy Neutron Model
Bohr- Solar System Model
Schroedinger- Electron Cloud Model
Periodic Table
Periods- horizontal rows on periodic table
The number of the period tells the number of electron shells each atom has.
Groups- Vertical columns on periodic table
The number of the group tells how many valence electrons each atom has.
All groups are named by the first atom in the group, with the exception of
Group 1A- Alkali Metals
Group 2A- Alkaline Earth Metals
Group 7A- Halogens
Group 8A- Noble Gases
Vocabulary
Valence Electrons- Electrons on the outer most shell of an atom
Electrons- located on the rings surrounding nucleus; negatively charged
Protons- located in the nucleus; positively charged
Neutrons – located in the nucleus; no charge
Atomic Number- Indicates Number of Protons
Atomic Mass- Number of Protons and Neutrons combined (To find Neutrons: Atomic Mass – Atomic
number)
Ions- A charged atom
Cations- Pawsitively charged atoms
Anions- Negatively charged atoms
Cations are located on the left side of the periodic table
Anions are located on the right side of the periodic table
Isotopes- Same number of protons and electrons, different number of neutrons
All elements want to fill their valence shell with 8 electrons and become ions.
If an atom has 3 or less valence electrons it will lose electrons and have a positive charge.
If an atom has 5 or more valence electrons it will gain electrons and have a negative charge.
Periodic Trends:
Ionization Energy (for periods and groups)
Electronegatively (for periods and groups)
Atomic Size (for periods and groups)