Science Paper 1 Flash cards

These flashcards cover key concepts from the Chemistry and Physics sections of the exam review.

What is the reactivity trend of group 1 metals in going down?

Group 1 becomes more reactive as the positive nucleus is further from the outer negative electron. This means the electrostatic forces are weaker. The single outer electron is more easily lost.

Define independent, dependent, and control variables.

Independent: what I change; Dependent: what I measure; Controls: what I keep the same.

What are the state symbols for solid, liquid, gas, and aqueous?

(s), (l), (g), (aq).

How did Mendeleev's periodic table differ from today's version?

Mendeleev arranged elements by atomic weight, left gaps for undiscovered elements.

What happens to boiling points in Group 7 (halogens) as you move down the group?

Boiling point increases down the group due to an increase in size of the atoms (increasing atomic radius), resulting in stronger intermolecular forces. More energy is required to break the intermolecular forces.

What is the electronic structure of noble gases (Group 0/8)?

Full outer electron shell (e.g., He 2; Ne 2,8; Ar 2,8,8).

How does reactivity change down Group 1 (alkali metals)?

Reactivity increases down the group.

Describe the color changes of universal indicator linked to pH levels.

Acid: red/orange/yellow; Neutral: green; Alkali: blue.

What are the pH ranges for substances?

Acid < 7, Neutral = 7, Alkali > 7.

How do you calculate concentration from mass and volume?

Conc = mass / volume; e.g., 3.2 g in 50 cm³ → 64 g dm⁻³.

What is a method to investigate temperature changes in reactions?

Insulate the container, measure initial temperature, add known mass, stir, measure.

Describe the extraction of aluminium by electrolysis.

Electrolyse molten aluminium oxide in cryolite; Al³⁺ gains electrons at the cathode.

What are the half-equations at electrodes during electrolysis?

Cathode (reduction): Al³⁺ + 3e⁻ → Al. Anode (oxidation): 2O²⁻ → O₂ + 4e⁻.

How do you calculate the rate from a graph?

Gradient = change in y / change in x (use tangent at a point).

What is the structure and bonding of giant ionic structures?

Giant ionic lattice of alternating positive and negative ions with strong electrostatic attractions.

What describes simple covalent structures?

Small molecules with strong covalent bonds within molecules but weak intermolecular forces.

How do you compare giant ionic structures and simple covalent structures?

Ionic: high mp/bp, conduct electricity when molten/aqueous as forms ions that are charged and free to move. Simple: low mp/bp, don’t conduct electricity.

How do you calculate the percentage by mass of an atom in a compound?

% by mass = (Ar × number of that atom) / Mr × 100.

How do you calculate the number of atoms in 1 g of an element?

Moles = mass/Ar; atoms = moles × 6.02×10²³.

What does a reaction profile graph show?

Label reactants, products, energy change (ΔH), activation energy.

Define gravitational potential energy in physics.

Ep = mgh.

How do you rearrange the gravitational potential energy equation?

m = Ep/(gh); h = Ep/(mg).

Describe the relationship between potential difference and current in an ohmic conductor.

Directly proportional (V ∝ I).

What are the symbols for circuit components?

Ammeter (A) in series; Voltmeter (V) in parallel; symbols for cell, lamp, resistor, switch, variable.

How does a variable resistor affect current?

Increasing resistance decreases current; decreasing resistance increases current.

What is the equation relating voltage, current, and resistance?

V = IR.

How do you calculate resistance from voltage and current?

R = V/I (with units, Ω).

How do you calculate current using power equation?

I = P/V (e.g., 6.9 kW at 230 V → 30 A).

How do you convert between Joules and kJ, and kW and W?

1 kJ = 1000 J; 1 kW = 1000 W.

Explain the difference between AC and DC current.

DC flows in one direction; AC repeatedly reverses direction.

How does particle motion change with temperature and pressure?

Higher temperature → greater kinetic energy → faster particles; higher pressure increases particle collisions.

How do you calculate specific latent heat?

E = mL or m = E/L (with units J).

Identify the state of matter at different temperatures.

Solid, liquid, gas identified based on melting and boiling points.

Describe particle arrangement in solids, liquids, and gases.

Solid: regular, closely packed. Liquid: close, random, move past each other. Gas: far apart, move freely.

How do you identify protons, neutrons, and electrons in an atom?

Protons = atomic number; Electrons = protons (in neutral atoms).

What is half-life?

Time for count/activity to halve.

What is count rate?

Counts per second (the rate of decay detected).

Determine half-life from a graph.

Find time for activity to fall to half its initial value; can step back from the graph.

Define the ionizing and penetrating power of α, β, and γ radiation.

α: strongly ionising, low penetration; β: moderate; γ: weakly ionising, high penetration.

Write the decay equations for α and β⁻ emissions.

α: mass −4, atomic −2, emit ⁴₂He. β⁻: neutron → proton + e⁻.

How is diffusion described in biology?

Net movement from high concentration to low concentration.

What is osmosis?

Movement of water through a partially permeable membrane.

How do you plot an osmosis graph for potatoes in different concentrations?

Plot % mass change vs concentration; include line of best fit.

Identify similarities and differences between light and electron microscopes.

Light uses light/optical lenses, lower resolution; electron uses electrons, higher resolution.

What are the similarities and differences between prokaryotes and eukaryotes?

Both have cell membrane and cytoplasm; prokaryotes lack a nucleus (DNA free) and are generally unicellular.

How do you calculate magnification from image size?

Magnification = image size / actual size.

Describe the stages of mitosis.

Prophase: chromosomes condense; Metaphase: chromosomes line up; Anaphase: chromatids separate; Telophase: nuclear membranes reform.

What are the food tests for glucose, starch, protein, and lipids?

Glucose: Benedict’s + heat → green/yellow/orange/brick-red; Starch: iodine → blue-black; Protein: Biuret → purple; Lipids: ethanol test → cloudy.

Where are protease and lipase enzymes made?

Protease: stomach, pancreas, small intestine. Lipase: made in pancreas and small intestine.

Explain how the body digests and absorbs proteins and fats.

Protease breaks down proteins into amino acids; lipase breaks down fats into fatty acids and glycerol; bile emulsifies fats and neutralizes.

How do viruses make you ill?

Viruses enter cells and reproduce inside, causing cell damage.

Describe the clinical trials for testing drugs and vaccines.

Test for toxicity/side-effects, efficacy, and dosage across phases; often double-blind.

What are the differences between benign and malignant tumors?

Benign: don’t invade, grow slowly, contained; Malignant: invade/spread, potentially life-threatening.

How are alveoli adapted for gas exchange?

Large surface area, thin walls, rich blood supply, moist surface.

What are coronary arteries?

Arteries that supply the heart muscle with oxygenated blood.

What is meant by angina?

Chest pain due to reduced blood flow to the heart muscle.

What are the effects of coronary artery constriction on the heart?

Less oxygen/glucose to muscle → less aerobic respiration → less energy → fatigue/possible heart attack.

Name common diseases and their pathogen types.

Measles (virus), salmonella (bacterium), rose black spot (fungus).

How is measles spread?

Airborne droplets from coughing or sneezing.

Explain how vaccinations work.

Vaccine contains dead/inactive pathogen or antigens → WBCs produce specific antibodies.

What is the balanced equation for photosynthesis?

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂.

How does temperature affect the rate of photosynthesis?

Rate increases with temperature to an optimum, then decreases rapidly.

What happens to enzymes in plant cells at higher temperatures?

Enzymes denature: active site changes shape so substrate cannot fit.

Where are plant stem cells found?

Meristems in the tips of roots and shoots.