1.1 Flashcards
What are the three states of matter according to the OCR Gateway A specification for GCSE Chemistry?
Answer: Solids, liquids, and gases.
Question: At what points do state changes occur?
Answer: State changes occur at the melting point (solid to liquid, liquid to solid) and at the boiling point (liquid to gas and gas to liquid).
Question: What is the difference between melting/freezing and boiling/condensing in terms of state changes?
Answer: Melting and freezing occur at the melting point, while boiling and condensing take place at the boiling point.
Question: When does evaporation occur, and at what temperature does it happen most rapidly?
Answer: Evaporation occurs at any temperature, but it happens most rapidly at the boiling point
Question: How are the three states of matter represented in a simple model according to the OCR Gateway A specification?
Answer: In the model, particles are represented by small solid spheres with different arrangements and movements for solids, liquids, and gases.
Solid
Arrangement of particles: Regular arrangement
Movement of particles: Vibrate about a fixed position
Closeness of particles: Very close
Liquid
Arrangement of particles: Randomly arranged
Movement of particles: Move around each other
Closeness of particles: Close
Gas:
Arrangement of particles: Randomly arranged
Movement of particles: Move quickly in all directions
Closeness of particles: Far apart
Question: What is a physical change in a substance according to the OCR Gateway A specification for GCSE Chemistry?
Answer: A physical change is a change that does not involve a change in the identity of the substance
Question: How is a chemical change or chemical reaction defined?
Answer: A chemical change is a change in which one or more substances are converted into different substances
Question: What are the substances that react in a chemical change called?
Answer: The substances that react in a chemical change are called the reactants.
Question: What are the substances formed by a chemical change called?
Answer: The substances that are formed by the chemical change are called the products.
Question: How do physical changes differ from chemical changes?
Answer: Physical changes involve changes in the forces between the particles of the substances, but the particles themselves remain the same, as do the chemical properties of the substance
Physical Changes
Definition: Changes in the forces between particles without altering the substance’s identity or chemical properties.
Reversibility: Relatively easy to reverse.
Interconversions:
Melting: Solid to a liquid
Boiling: Liquid to a gas (from below surface as well as at surface)
Freezing: Liquid to a solid
Evaporation: Liquid to a gas (at surface only)
Condensation: Gas to a liquid
Sublimation: Solid to a gas
Chemical Changes:
Definition: Involves the conversion of one or more substances into different substances.
Reactants: Substances that undergo the chemical change.
Products: Substances formed by the chemical change
Front of flashcard:
Question: What does the particle theory explain regarding changes in state of matter according to the OCR Gateway A specification for GCSE Chemistry?
Answer: The particle theory explains how matter changes state depending on the energy and forces present between the particles in the substance.
Question: How does the amount of energy needed for state changes (e.g., solid to liquid, liquid to gas) depend on the strength of forces between particles?
Answer: The stronger the forces between the particles, the higher the energy needed for melting and boiling to occur
Question: What happens to particles when a substance is heated, according to the particle theory?
Answer: When substances are heated, the particles absorb thermal energy which is converted into kinetic energy, causing them to vibrate more and eventually overcome intermolecular forces to change state
Question: What are some limitations of the particle theory?
Answer: The limitations include considering all particles as small, solid, and inelastic, without considering differences between particles such as atoms, ions, or molecules, and neglecting to account for intermolecular forces between different particles in different substances.
