Flashcards in 7.1 - The Periodic Table Deck (4)
What was the prior periodic table like?
- Only 60 known elements
- Arranged in order of atomic mass
- No knowledge of subatomic particles
- Elements were swapped in places where their properties didn't match their groups
- Gaps were left in the periodic table for predicted and undiscovered elements
How are elements arranged in the modern day periodic table?
- Elements from L to R, arranged in order of increasing atomic number (each successive member with 1 extra proton)
- Groups (18) are vertical columns - each element in a group has the same number of electrons in its outer shell
- Periods (7) are horizontal rows - each element in a period has the same number of the higher energy electron shell
Repeating trend in properties across elements in the period.