CCEA GCSE Chemistry 1.6 The Periodic Table Exam Questions

About CCEA GCSE Chemistry 1.6 The Periodic Table

The Periodic Table is a Unit 1 topic in CCEA GCSE Chemistry that uses electronic configuration to explain patterns in properties. You need to know how Mendeleev arranged the elements and why his table was accepted, how the modern table is organised, and the properties and trends in Group 1 (alkali metals), Group 7 (halogens) and Group 0 (noble gases). Transition metals are compared with Group 1 metals. It links to atomic structure, bonding and the reactivity series in Unit 2. Examiners often ask for observations when alkali metals react with water, halogen displacement reactions and explanations of reactivity trends in terms of outer electrons and distance from the nucleus.

What you need to know

• Development Mendeleev arranged elements by atomic mass but swapped some to keep similar elements in groups, and left gaps for undiscovered elements whose properties he predicted correctly. The modern table is arranged by atomic number.
• Group 1 Soft metals stored under oil. With water they float, move around, fizz and form an alkaline hydroxide solution and hydrogen, for example 2Na + 2H2O → 2NaOH + H2. Sodium melts into a ball and potassium burns with a lilac flame. Reactivity increases down the group because the outer electron is further from the nucleus, more shielded and lost more easily.
• Group 7 Diatomic non-metals. Chlorine is a yellow-green gas, bromine a red-brown liquid and iodine a grey-black solid that forms a purple vapour. Reactivity decreases down the group because it is harder to gain an electron as the outer shell is further from the nucleus.
• Halogen displacement A more reactive halogen displaces a less reactive one from a solution of its salt, for example Cl2 + 2KBr → 2KCl + Br2, turning the solution orange or yellow-orange.
• Group 0 Noble gases have full outer shells, so they are very unreactive and exist as single atoms. Uses: helium in balloons, neon in advertising signs, argon in filament lamps.
• Transition metals Compared with Group 1 metals they have higher melting points and densities, are harder and stronger, react much less vigorously, form coloured compounds and are often used as catalysts.

Common mistakes in 1.6 The Periodic Table

• Saying Group 1 metals sink in water. They float because they are less dense than water.
• Explaining reactivity trends only by saying there are more shells. Mention distance from the nucleus, shielding and the attraction to the outer electron.
• Describing the trend in Group 7 reactivity as increasing down the group. It decreases down Group 7.
• Stating that noble gases are unreactive because they have eight outer electrons. Helium has two; the key point is a full outer shell.
• Giving gas products as observations. Write fizzing or bubbles, not hydrogen is produced, when asked what you see.

Try three 1.6 The Periodic Table exam-style questions