Germany Jahrgangsstufe 10 Chemistry (NTG track)

Chapters: 4

1. How chemists think and work

How chemists think and work

The Scientific Method – The scientific method is the careful way scientists find out how the world works. Observe something, ask a testable question, make a hypothesis (a clear, testable guess), test it with a fair experiment (change one variable, measure one, keep the rest the same), repeat and record data, analyse it, draw a conclusion and share it so others can check. Results that fail the test are useful too: they send you back to a new hypothesis.

Acids and bases as proton transfer

Acids and Bases: Properties, Indicators and Reactions – An acid gives H⁺ ions in water and a base gives OH⁻ ions. Indicators show which one is present by a colour or smell change, and when H⁺ meets OH⁻ they make water, leaving a salt behind.

Redox reactions: electron transfer

Redox Reactions: From Oxygen to Electron Transfer – Oxidation first meant adding oxygen or removing hydrogen. Reduction meant the opposite. Today we use a bigger idea: oxidation is losing electrons and reduction is gaining electrons. Both always happen together, so we call them redox reactions. A more active metal gives electrons to the ion of a less active metal.

Esters: formation, hydrolysis and uses

Types of Organic Reactions and Their Mechanisms – Organic reactions are sorted by what happens to the molecule: substitution (one atom swaps for another), addition (atoms join across a double bond), elimination (a small molecule leaves and a double bond forms), condensation (two molecules join and lose water) and hydrolysis (water splits a molecule). The mechanism shows how electrons move: bonds break homolytically (radicals) or heterolytically (ions), and nucleophiles (electron-rich) attack electrophiles (electron-poor). Esters form from acids and alcohols in a reversible, acid-catalysed condensation and are split by hydrolysis.