Atomic radius
- One-half of the distance from center to center of two like atoms.
Shielding effect
- The reduction of the attractive force between a nucleus and its outer electrons due to the blocking effect of inner electrons.
Ionization energy
- The amount of energy needed to remove and electron from a specific atom or ion in its ground state in the gas phase.
Electronegativity
- The tendency for an atom to attract electrons to itself when it is combined with another atom.
Group 18 (Noble gases or Inert gases)
- Un-reactive
- Electron configuration is very stable
- Many uses
- Helium, neon, argon: Never have been prepared
- Xenon, Krypton, Radon: Low reactivity
Group 1 (Alkali metals)
-Highly reactive metals
-Soft that they can be cut with a knife
-Produce alkaline solutions
Group 2 (Alkaline-earth metals)
- Harder, Denser, Stronger than group 1
- igher melting points than group 1
- All reactive but less reactive than group 1
Transition elements
- Group 3 ~ Group 12
- All metals
- Not as reactive as group 1 and 2
- Harder, denser and have higher melting points than the group 1 and 2
Lanthanides
- Elements 58 ~ Elements 71
- Shiny, reactive metals
Actinides
- Elements 90 ~ Elements 103
- Unstable arrangement of protons and neutrons in the nucleus
- Radioactive forms
- Best example: Uranium
Main-block elements
- Group 13 ~ 18
- Representative elements
- Systematically
Hydrogen
- One element forms its own chemical family
- Behaves unlike any other element
- Reacts so easily
How are elements created? How How can atoms be counted or measured?
