Electronic Configurations Flashcards
All 5 cards in this deck
What are the steps to write the electronic configuration of one of the first 20 elements?
e.g. sodium, atomic number 11
- Number of electrons = atomic number: 11
- Fill shells 2, then 8, then 8: 2, 8, 1 left
- Write with dots between shells: 2.8.1
How many electrons can the first, second and third shells hold for the first 20 elements?
First shell 2, second shell 8, third shell 8 (then the fourth shell starts).
Explain, in terms of electrons, why two elements are in the same group of the periodic table.
They have the same number of electrons in their outer (electron) shell.
How is the period an element is in related to its electronic configuration?
The period number equals the number of shells holding electrons.
e.g. chlorine (2.8.7) has three occupied shells, so it is in period 3
How is the group number of an element in Groups 1–7 related to its electronic configuration, and what is different about Group 0?
In Groups 1–7, the group number is the number of electrons in the outer shell, e.g. oxygen (2.6) is in Group 6.
Group 0 doesn't follow this: its atoms already have a complete outer shell (two electrons in helium, eight in the others).