270 likes | 443 Views
Coulomb Forces. If the charges on the particles have opposite signs, the force will be one of attraction . If the charges on the particles have the same signs, the force will be one of repulsion. Coulomb’s Law.
E N D
Coulomb Forces If the charges on the particles have opposite signs, the force will be one of attraction. If the charges on the particles have the same signs, the force will be one of repulsion.
Coulomb’s Law Forces between objects become stronger as they move together and weaker as they move apart.
Atomic Radius The distance from the center of the atom’s nucleus to its outermost electron.
Atomic Radius Trends Within a group of elements, as the atomic number increases, atomic radius increases.
WHY?? Within a group each successive element has: a larger kernel More occupied energy levels Larger shielding effect
Shielding • The electron in the outermost energy level experiences more inter-electron repulsion (shielding). • Second electron has same shielding, if it is in the same period
Within a period of elements, as atomic number increases, atomic radius decreases. Atomic Radius Trends
WHY?? Across a period: Larger # of protons Greater attraction for nucleus Same valence shell
Ionization Energy The energy required to remove the most loosely held electrons.
Ionization Energy Within a group, as atomic number increases, Ionization energy decreases.
WHY?? - Greater number of energy levels. - greater distance from nucleus - energy levels shield outer electrons-The shielding effect.
Ionization Energy Within a period, as atomic # increases, ionization energy increases due to increase of electrons.
WHY?? Across a period: Larger # of protons Greater attraction for nucleus (nuclear charge) Same valence shell/same shielding effect
Electron Affinity The ability of an atom to accept one or more electrons resulting in an energy change.
Electronegativity The tendency of an atom in a molecule to attract shared electrons to itself.
In general, nonmetals have a higher: ionization energy, electron affinity, and electronegativity. Exception: Noble Gases