Grade 10 · Theory
The periodic table
Atomic structure · about 3 min
Visual overview: The periodic table1 MIN READ
2 study sections · pause after each one and recall the key ideaThe periodic table organises elements so that properties repeat predictably.
Key points- Groups (columns) share the same number of valence electrons and similar chemistry.
- Periods (rows) show a repeating pattern of properties.
- Atomic radius decreases across a period and increases down a group.
- Ionisation energy increases across a period and decreases down a group.
- Group — a column; Period — a row.
- Ionisation energy — the energy needed to remove an electron.
EXAM TIP
explain trends with two ideas only — nuclear charge and the number of shells (shielding).