Periodic System for Chemists

Your periodic table, always with you.

Use it offline. Find elements quickly. Keep favorites and personal notes on iPhone and iPad.

Back to Selenium

Selenium Period

Se - Atomic Number 34

Period
4
Ranking:
#34 of 118
Highest
H: 1.00
Lowest
Og: 7.00

About the Period

Horizontal row in the periodic table indicating the number of electron shells.

Top 10 by Period

Top 10 by Period

#1 H Hydrogen
1.00
#2 He Helium
1.00
#3 Li Lithium
2.00
#4 Be Beryllium
2.00
#5 B Boron
2.00
#6 C Carbon
2.00
#7 N Nitrogen
2.00
#8 O Oxygen
2.00
#9 F Fluorine
2.00
#10 Ne Neon
2.00

Related Properties

BlockGroupseries_id

iPhone & iPad

Your periodic table, always with you.

  • Access element data offline, in the lab or in class.
  • Find elements quickly by name, symbol, or atomic number.
  • Save favorite elements and add your own notes.
Published App Store screenshots: periodic table, element details, and search (English).