1. Periodic Table
Chemistry

2. Periods and Groups
Periods: horizontal rows, with a given pattern of changing behavior.
Groups: vertical columns, with similar chemical and physical properties.

3. History Dobereiner: triads of elements.
Mendeleev: arrangement by increasing atomic mass.
Left spaces and predicted that new species would be found to fill in, with appropriate properties.
Gallium and Germanium filled in these spots, confirming the type of arrangement.

4. Periodicity
Elements now arranged by increasing atomic number, not mass.
Periodicity is the repetition of the physical and chemical properties.
This is also called periodic law.

5. Classes of elements
Metals
Nonmetals
Metalloids

6. Metals Metals: c. 80% of the elements.
Good conductors of heat and electricity.
All solids at room temperature except Hg.
Most are silver-gray in color.
All have relatively mobile valence electrons.

7. Nonmetals Great variation in their physical properties.
Most are gases, one liquid, a few solids.
Poor conductors of heat and electricity, except for Carbon.
Solids tend to be brittle.

8. Metalloids
These elements have some properties like metals and nonmetals.
They may change how they behave if small amounts of other elements are added.

9. Element Classifications
Special names
Alkali metals
Alkaline earth metals
Halogens
Noble gases
Representative elements: those with incomplete s & p sublevels
Transition elements: d & f sublevels
(Lanthanides: formerly known as rare-earths)
--Think in terms of blocks of sublevels for categorizing

10. Periodic Trends: see figures 6.14-21, table 6.1
Atomic size: decreases generally L→R
Atomic size: increases generally T →B
Ionization energy: decreases gen. T →B
Ionization energy: increases gen. L→R
Ionic size: decreases generally L→R
Ionic size: increases generally T →B
Refer to earlier power-point ed out for more information on these.

11. Electronegativity The ability to attract electrons when in a compound.
In general, decrease from top to bottom, increase from left to right.
See table 6.2,
Overall summary fig. 6.22, 178.