DE_Chem_2.5.2-3

DE_Chem_2.5.2_How Can the Observed Periodic Trends In Reactivity of the Elements Be Explained?

​1. The pattern that emerges from these observations is that, for many atoms, the closer the atom is to being able to achieve eight valence electrons in its s and p orbitals, the more reactive it is.
2. Because the alkali metals lose electrons to achieve stability, greater shielding results in greater reactivity.
3. The nonmetals, however, gain electrons to achieve stability instead of losing them, and the increase in shielding decreases reactivity in the lower periods of a group because the pull of the nucleus is limited.

DE_Chem_2.5.3_What Other Periodic Trends Besides Reactivity Occur, and How Are They Explained?

​Factors affecting Periodic Trends

Periodic Table Trends

Multiple Choice

The number of valence electrons can be determined by the...

• group number

• atomic number

• average atomic mass

• period number

Multiple Choice

The number of energy levels (electron orbitals) can be determined by the...

• group number

• atomic number

• average atomic mass

• period number