Electronic Configurations Flashcards
All 4 cards in this deck
What are the steps to write the electronic configuration of one of the first 20 elements?
e.g. calcium (atomic number 20)
- Number of electrons = atomic number: 20.
- Fill the shells in order, up to 2, then 8, then 8: 2.8.8.
- Put the remaining electrons in the next shell: 2.8.8.2.
How does an element's electronic configuration tell you its period?
e.g. chlorine, 2.8.7
The number of shells (numbers in the configuration) is the period number: chlorine has 3 shells, so it is in period 3.
True or false? Potassium and caesium are in the same group because they have the same number of electron shells.
False. They are in the same group because they have the same number of electrons (1) in their outer shell.
How does an element's electronic configuration tell you its group?
e.g. chlorine, 2.8.7
For groups 1 to 7, the number of electrons in the outer shell is the group number: chlorine has 7, so it is in group 7. Group 0 elements have a full outer shell.