PreAP Chemistry

Chapter 5 Notes

Periodic Law – properties of the elements are a periodic function of their atomic number

The moon’s phases and magazine subscriptions are also periodic…

Atomic Radius – (size) increases as you move top to bottom within a group or family

(increases because the energy levels increase → high energy means further from the nucleus)

Atomic Radius – (size) increases as you move top to bottom within a group or family

decreases as you move left to right because of effective nuclear charge → more protons in the nucleus to attract the electrons closer

Effective Nuclear Charge (ENC) – pull of the nucleus on the valence energy level electrons (outer energy level electrons)

increases left to right

Ionization Energy (IE) – energy required to remove an electron from a gaseous atom

increases bottom to top and left to right

Electron Affinity (EA) – energy released when an electron is added to a gaseous atom

increases bottom to top and left to right

Electronegativity – (EN) – measure of an atom’s pull on another atom’s electrons

increases bottom to top and left to right

Shielding – layers of electrons that protect valence electrons from the pull of the nucleus

increases top to bottom and constant left to right

metallic character – ease of losing an electron

increases top to bottom and right to left

nonmetallic character – ease of gaining an electron

increases bottom to top and left to right

ions – charged particles

cations – postive ion formed from an atom losing an electron

the atomic radius is always smaller than the parent atom because of fewer energy levels

Anions – negative ion formed from an atom gaining an electron

the atomic radius is always larger than the parent atom because of electron repulsion

Atomic Radius

Ionization Energy, Electron Affinity, Electronegativity

Effective Nuclear Charge

Shielding

Metallic Character

Nonmetallic Character