Warm Up : November
1. Write the electron configurations for magnesium and calcium.
2. What do these configurations have in common?
3. Where are these two elements located on the periodic table?
4. Without writing the entire configuration, predict how the electron configuration of barium ends.

Electron Configurations and the Periodic Table
• The periodic table is arranged by how the electrons within an atom fill orbitals.
• The periodic table is broken into blocks according to how the electron configuration of an atom ends.
• s-block
– Configurations end in s 1 or s 2
– Composed of groups 1 and 2
– Group 1 called alkali metals (except H)
– Group 2 known as alkaline earth metals

Electron Configurations and the Periodic Table
• P-block
– Configurations end in p 1 – p 6
– Compose elements that make up groups 13-18
(except He)
– Group 17 also called halogens (most reactive nonmetals)
– Group 18 also known as noble gases
• The s-block and p-block together are known as the main group elements.

• d-block
– Elements whose configurations end in d 1 – d 10
– d-block elements also known as transition elements.
– Metals in the d-block tend to have higher melting points, are harder, more dense, and less reactive compared to the metals found in the s-block.
• f-block
– Elements whose configurations end in f 1 – f 14 .
– Composed of elements that make up lanthanide and actinide series.

• When writing electron configurations using the periodic table,
– the number in front of the s is the period number
– the number in front of the p is the period number
– the number in front of the d is one less than the period number
– the number in front of the f is two less than the period number

Using the period table, write the electron configuration for these atoms:
(a) phosphorus (P)
(b) tin (Sn)

• Sometimes we are only interested with electrons in the highest energy level (Valence electrons).
• In noble gas configurations, we start with the noble gas before the element and build from there.
• Bromine (Br)
[Ar] 4s 2 3d 10 4p 5

Write noble gas electron configurations for these atoms:
(a) aluminum (Al)
(b) barium (Ba)

• Give the identity, the block, period, and group for the atom that has the following shorthand configuration
[Ar] 4s 2 3d 10 4p 3
Identity: _________ Period:_________
Block: ___________ Group:_________

• Respond to the following…
– What is most important thing you learned today?
– What question you would still like answered?
– What is one way what you have learned today connects with what you knew before?