Nuclear Pull Seen from Position
The periodic table can be read like a seating chart for elements. An element's position gives clues about atomic size, how easily an electron is removed, and how strongly the atom pulls electrons in a bond.
The key idea is nuclear attraction toward valence electrons. Valence electrons are electrons in the outer shell. When the number of protons increases, the nuclear pull usually becomes stronger. When the number of shells increases, valence electrons are farther from the nucleus and feel a weaker pull.
Periodic Trend Model
Pick one property, then compare the period track and the group track. The model shows the direction first so the terms feel less abstract.
- Read as
- Relative atomic size, usually in .
- Across a period
- From to , the size decreases.
- Down a group
- Closest reason