Astatine has 7 valence electrons.
We can write the valence electrons of astatine using two different methods:
#1 Using periodic table
#2 Using electron configuration
Let’s break down each method in detail.
#1 Using Periodic Table
Get the periodic table having the chemical elements marked on it as mentioned above.
Now mark the location of astatine on the periodic table.
Next, mark the group number of astatine on the periodic table.
The valence electrons of each main group element can be determined by the column in which it is located.
(i.e., all group 1 elements have 1 valence electron, all group 2 elements have 2 valence electrons, skip the transition metals… then, all group 13 elements have 3 valence electrons, all group 14 elements have 4 valence electrons, and so on up to group 18 elements)
Since astatine is in group 17, it has 7 valence electrons.
#2 Using Electron Configuration
- First, write electron configuration of astatine
The electron configuration of astatine is [Xe] 6s2 4f14 5d10 6p5.
- Second, find highest energy level in electron configuration
In the above electron configuration, the highest energy level (6) is marked with green color.
- Finally, count electrons of that energy level
The 6th energy level contains 6s and 6p subshells. There are 2 electrons in the 6s subshell and 5 electrons in the 6p subshell. So astatine has a total of 2 + 5 = 7 valence electrons.
Next: Radon Valence Electrons