Chemistry C3 Part One

1. Chemistry C3 Part One Revision PowerPoint - Big ideas The Periodic Tableorganising elements into groups

2. Newlands and Mendeleev • Newlands listed the elements in order of atomic weights. He spotted repeating patterns (octaves) in behaviour • Mendeleev arranged elements into groups and periods to fit repeating patterns. He left gaps for undiscovered elements.

3. Modern Periodic Tables • Modern Periodic Tables arrange elements by increasing atomic number. • The number of electrons in the highest energy level (outermost shell) indicates the group number of the element.

4. Group 1 - The Alkali Metals • Elements in Group 1 (The Alkali Metals) are soft, low density metals. • Alkali metals react rapidly with water, forming alkalis & hydrogen. • Alkali metals form ionic compounds with non-metals. • Group 1 ions have the charge +1

5. Reactivity down the group • Group 1 elements become more reactive further down the group. • Large atoms lose electrons from their outer shells more easily because they are further from the positive nuclear charge force and shielded by more inner shells of electrons.

6. Group 7 – The Halogens • Elements in Group 7 (The Halogens) are coloured non-metals. • More reactive halogens displace less reactive halogens from solutions containing halide ions, e.g. Cl2 + 2Br– → Br2 + 2Cl– • Group 7 ions have a charge of –1