This key facts covers Trends in the Periodic Table within The Periodic Table for GCSE Chemistry. Revise The Periodic Table in Atomic Structure for GCSE Chemistry with 22 exam-style questions and 24 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 6 of 13 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
📈 Trends in the Periodic Table
Down a group:
- Atomic radius increases (more electron shells)
- Group 1 reactivity INCREASES (outer electron further from nucleus, easier to lose)
- Group 7 reactivity DECREASES (harder to attract an electron into a larger atom)
- Melting/boiling points — trend varies by group
Across a period (left to right):
- Atomic radius decreases (more protons pull electrons closer)
- Metallic character decreases (metals → non-metals)
- Elements go from highly reactive metals → non-metals → noble gas
Quick Check: An element is in Group 2, Period 3. How many outer electrons does it have and how many electron shells?
2 outer electrons (Group 2) and 3 electron shells (Period 3). This is magnesium, with electronic configuration 2,8,2.
Practice questions for The Periodic Table
How are elements arranged in the modern periodic table?
Mendeleev's periodic table was eventually accepted by other scientists. Explain why scientists were convinced that his table was correct.