📚 Topic Summary
Atomic radius refers to the typical distance from the nucleus to the outermost electron shell of an atom. It's not a fixed value because electron clouds don't have definite boundaries, but we can measure it effectively. The periodic trends for atomic radius are crucial in chemistry: atomic radius generally increases as you move down a group (column) due to added electron shells, and it generally decreases as you move from left to right across a period (row) due to increasing effective nuclear charge.
Understanding these trends helps predict various chemical properties and behaviors. Let's test your knowledge with some practice!
🧪 Part A: Vocabulary
Match the following terms with their definitions:
- Atomic Radius
- Effective Nuclear Charge
- Ionization Energy
- Electron Shielding
- Periodic Trend
Definitions:
- The distance from the nucleus to the outermost electron.
- The ability of core electrons to reduce the nuclear charge experienced by valence electrons.
- The trend of atomic properties across a period or down a group in the periodic table.
- The net positive charge experienced by an electron in a multi-electron atom.
- The energy required to remove an electron from an atom.
📝 Part B: Fill in the Blanks
Complete the following paragraph using the words provided: increases, decreases, nuclear charge, electron shells, left, right.
As you move down a group in the periodic table, the atomic radius generally ___________ because of the addition of more ___________. As you move from ___________ to ___________ across a period, the atomic radius generally ___________ due to an increase in ___________.
🤔 Part C: Critical Thinking
Explain why the atomic radius of potassium (K) is larger than that of sodium (Na), even though they are both in Group 1.
