Group 0, 1, 7 and Transition Metals

Group 1 - Alkali Metals are the most reactive metals you'll encounter. They have just one electron in their outer shell, which makes them desperate to give it away. When they meet water, they create a proper show - fizzing, sparking, and producing hydrogen gas plus an alkaline solution.

The reactivity increases as you go down the group. Lithium just fizzes steadily, sodium melts into a ball and disappears quickly, whilst potassium ignites with sparks and a lilac flame. All three react with oxygen to form white oxides and with chlorine to create white precipitates.

Group 7 - Halogens work in the opposite way. These non-metals have seven outer electrons and desperately want one more to complete their set. They exist as pairs (like Cl₂) and form ionic compounds with metals or covalent compounds with non-metals.

Key Pattern: Halogens become less reactive going down the group because larger atoms struggle to attract that final electron they need.

Group 0 - Noble Gases are the chilled-out elements with complete outer shells (8 electrons, or 2 for helium). They're unreactive because they're already satisfied - no need to gain or lose electrons. Their boiling points increase down the group.

Transition Metals are the workhorses - harder, stronger, and with higher melting points than alkali metals. They're brilliant catalysts and much less reactive with water and oxygen, making them perfect for construction and electronics.