How the periodic table is arranged, trends in Group II and Group VII, trends across Period 3, and predicting the properties of an element from its position.
5 narrated scenes. Press play, listen and read along — the points appear as they are explained. Use ‹ Prev / Next › or the scene bar to jump to any scene.
Mendeleev left gaps in his table and predicted what the missing elements would be like. When they were discovered his predictions were right.
Narration uses your device’s built-in voice. No sound? Switch to “Captions only” — the captions advance on their own.
Copy these into your notebook in your own words — that is how they stick.
Increasing atomic number; groups = same outer electrons; periods = number of shells.
Reactivity increases down the group (outer electrons lost more easily).
F₂ gas, Cl₂ gas, Br₂ liquid, I₂ solid; boiling point rises down the group.
Oxidising power decreases down the group; Cl₂ displaces Br⁻ and I⁻.
Metallic to non-metallic across; oxides basic → acidic.
Increases across Period 3 (Na → Cl).
Triads of similar elements; gaps for undiscovered elements.
Use group and period to predict properties.
3 quick games on this lesson. Earn XP and badges as you play — your best score for each game is saved. Games are for practice and do not change your exam readiness. More games in the Chemistry Arcade.
8 items modelled on real CSEC Paper 1 questions. Choose one answer for each, then check. Aim for 80% or better. Work each item on paper first.
Write full answers, then reveal the mark scheme and tick the points you earned (15 marks in total). Show all your working — method marks count. Your answers are saved on this device.
Question 1 [15 marks]
The first twenty elements are arranged in the periodic table. Element X has atomic number 19.
(a) (a) State the basis for the arrangement of elements in the periodic table. [1]
(b) (b) Write the electron arrangement of X and state its group and period. [3]
(c) (c) State the trend in reactivity of the Group II metals going down the group and explain it. [3]
(d) (d) Describe what you would observe when calcium reacts with cold water, and write a word equation. [3]
(e) (e) State the colour and physical state at room temperature of chlorine, bromine and iodine. [3]
(f) (f) Explain why chlorine displaces bromine from potassium bromide solution. [2]
Find these in your own past-paper booklets for extra timed practice. Items above are written in the style of these papers; any adapted from a specific question say so.