Chemistry Basics: Matter and Changes of State

Chemistry

• Chemistry is the study of matter and its properties, as well as how matter changes.
• Matter is anything that has mass and takes up space.
• Pure substances are substances that are made up of only one type of particle.
• Mixtures are made up of two or more substances that are not chemically combined.
• Mechanical mixtures are heterogenous mixtures where the different components are visible.
• Solutions are homogeneous mixtures where the different components are not visible.
• Alloys are mixtures of two or more metals.

Changes of State

• Melting is the change from a solid to a liquid.
• Freezing is the change from a liquid to a solid.
• Evaporation is the change from a liquid to a gas.
• Condensation is the change from a gas to a liquid.
• Sublimation is the change from a solid to a gas.
• Deposition is the change from gas to a solid.

Classifying Matter

• A solution is a homogeneous mixture where the different components are not visible and cannot be easily separated.
• A mechanical mixture is a heterogeneous mixture where different components are visible. The components can be easily separated using physical methods.

Particle Theory

• All matter is made up of tiny particles.
• The particles are always in motion.
• The particles are attracted to each other.
• The amount of attraction between particles depends on the type of particle it is.
• There are spaces between particles.

Particle Diagrams

• Solids have particles that are tightly packed together and vibrate in a fixed position.
• Liquids have particles that are more loosely packed and are able to flow past one another.
• Gases have particles that are very far apart and move around randomly.

Changes of State & Particle Theory

• Melting occurs when the particles of a solid gain enough energy to overcome the attractive forces between them, allowing them to move around more freely.
• Freezing occurs when particles lose enough energy to become attracted to each other and remain in a fixed position.
• Evaporation occurs when particles at the surface of a liquid gain enough energy to escape into the air as a gas.
• Condensation occurs when particles in the gas phase lose enough energy to slow down and clump together as a liquid.
• Sublimation occurs when particles in a solid gain enough energy to directly escape into the air as a gas.
• Deposition occurs when particles in the gas phase lose enough energy to directly stick together as a solid.

Physical Properties

• A physical property is a characteristic of a substance that can be observed or measured without changing the identity of the substance.
• Qualitative properties are descriptions that do not involve numbers (e.g., color, odor, state).
• Quantitative properties are descriptions that involve numbers and units (e.g., mass, volume, density).
• A physical change is a change in the state or appearance of a substance, but not its chemical composition (e.g., melting, freezing, boiling, cutting, dissolving).

Chemical Properties

• A chemical property is a characteristic of a substance that describes how it reacts with other substances.
• A chemical change is a change that results in the formation of a new substance, and cannot be reversed through a physical change (e.g., burning, rusting, cooking).
• Evidence of a chemical change includes:
  • Color change
  • Gas production
  • Odor change
  • Heat or light production
  • Precipitate formation

Characteristic Properties

• A characteristic property is a property that is unique to a substance and can be used to identify it (e.g., density, melting point).
• Density is a measure of how much mass is contained in a given volume. Density can be calculated using the formula: Density = Mass / Volume.
• The GRASS method can be used to solve density, mass, and volume problems.

Elements and Compounds

• An element is a pure substance that cannot be broken down into simpler substances by chemical means.
• An element symbol is a one or two letter abbreviation for an element.
• A compound is a pure substance made up of two or more elements that are chemically combined in a fixed ratio.
• A chemical formula represents the ratio of elements in a compound.
• The chemical formula indicates the number of atoms of each element in a molecule.
• Electrolysis of water is the process of using electricity to decompose water into hydrogen and oxygen gas.

Metals, Non-Metals & Metalloids

• Metals are usually lustrous, malleable, ductile, and good conductors of heat and electricity.
• Non-metals are usually dull, brittle, and poor conductors of heat and electricity.
• Metalloids have properties of both metals and non-metals.

Chemical Tests for Gases

• Oxygen produces a glowing splint.
• Carbon Dioxide turns limewater milky.
• Hydrogen produces a "popping" sound when a lit splint is held near the gas.

This quiz covers the fundamental concepts of chemistry, focusing on the properties of matter, classifications such as pure substances and mixtures, and the changes of state. Test your knowledge on various types of mixtures, like mechanical mixtures and solutions, as well as the processes of melting, freezing, evaporation, and more.