Section 2 Flashcards

Groups 1 & 7

Groups 1 & 7: read all 6 questions and answers

1. Give the flame test colours for Li⁺, Na⁺, and K⁺.
   Lithium: Crimson Red. Sodium: Yellow-Orange. Potassium: Lilac.
2. Describe the observations when potassium reacts with water.
   Melts into a ball, floats, moves rapidly across the surface, ignites with a lilac flame, and disappears with a small explosion.
3. Explain why reactivity increases down Group 1.
   Atoms get larger, so the outer electron is further from the nucleus and experiences more shielding. The electrostatic attraction is weaker, so the outer electron is lost more easily.
4. Describe the physical state and colour of Chlorine, Bromine, and Iodine at room temperature.
   Chlorine: pale green gas. Bromine: red-brown liquid. Iodine: grey-black solid.
5. Explain why reactivity decreases down Group 7.
   Atoms get larger, so the outer shell is further from the nucleus with more shielding. The attractive force of the nucleus on an incoming electron is weaker, so an electron is gained less easily.
6. Write the ionic equation for the reaction between chlorine and potassium bromide.
   Cl₂(aq) + 2Br⁻(aq) → 2Cl⁻(aq) + Br₂(aq).

Gases in the Atmosphere & Reactivity

Atmosphere & Reactivity: read all 5 questions and answers

1. State the approximate percentage composition of Nitrogen and Oxygen in clean dry air.
   Nitrogen: approx. 78%. Oxygen: approx. 21%.
2. How does carbon dioxide act as a greenhouse gas?
   It absorbs long-wavelength infrared radiation re-radiated by the Earth and re-emits it in all directions, trapping heat in the atmosphere.
3. Define reduction and oxidation in terms of oxygen transfer.
   Oxidation: gain of oxygen. Reduction: loss of oxygen.
4. State the conditions required for iron to rust.
   Water (moisture) and oxygen must both be present.
5. Explain the difference between barrier methods and sacrificial protection for preventing rust.
   Barrier methods (painting, oiling) physically block water and oxygen from reaching the iron. Sacrificial protection uses a more reactive metal (like zinc) that oxidises preferentially instead of the iron.

Extraction of Metals & Acids

Extraction & Acids: read all 5 questions and answers

1. How are metals below carbon in the reactivity series extracted?
   By heating their oxides with carbon (carbon reduction), where carbon acts as a reducing agent by removing oxygen (e.g., in a blast furnace).
2. How are metals above carbon in the reactivity series extracted?
   By electrolysis of their molten compounds (e.g., aluminium from molten alumina), which requires massive electrical energy.
3. Explain why alloys are harder than pure metals.
   Alloys contain atoms of different sizes that disrupt the regular layers of the metal lattice, preventing the layers from sliding over one another easily.
4. Define acid and base in terms of proton transfer.
   Acid: a proton (H⁺) donor. Base: a proton (H⁺) acceptor.
5. What type of salt is produced by hydrochloric acid, sulfuric acid, and nitric acid?
   Hydrochloric acid produces chlorides. Sulfuric acid produces sulfates. Nitric acid produces nitrates.

Chemical Tests

Chemical Tests: read all 6 questions and answers

1. Describe the test and observation for Hydrogen, Oxygen, Carbon Dioxide, and Chlorine gases.
   Hydrogen: squeaky pop with a lit splint. Oxygen: relights a glowing splint. Carbon dioxide: turns limewater cloudy. Chlorine: bleaches damp blue litmus paper white.
2. Describe the test and observation for Ammonium ions (NH₄⁺).
   Add sodium hydroxide solution and warm gently. Damp red litmus paper held at the mouth of the tube turns blue due to ammonia gas.
3. Describe the tests and observations for Cu²⁺, Fe²⁺, and Fe³⁺ ions.
   Add sodium hydroxide solution. Copper(II) forms a blue precipitate. Iron(II) forms a green precipitate. Iron(III) forms a brown precipitate.
4. Describe the test and observations for halide ions (Cl⁻, Br⁻, I⁻).
   Add dilute nitric acid, then silver nitrate solution. Chloride forms a white precipitate. Bromide forms a cream precipitate. Iodide forms a yellow precipitate.
5. Describe the test and observation for sulfate ions (SO₄²⁻).
   Add dilute hydrochloric acid, then barium chloride solution. A white precipitate of barium sulfate forms.
6. Describe the test and observation for carbonate ions (CO₃²⁻).
   Add dilute hydrochloric acid. Fizzing (effervescence) is observed, and the gas produced turns limewater cloudy.