Understanding Science: Methods, Matter, and Elements

Science

• A systematic approach to understanding the natural world is achieved through observation, experimentation, and analysis.
• The aim is to discover facts and relationships, leading to the formulation of laws and theories.
• This approach relies on evidence-based reasoning.
• It is subject to change based on new findings.
• The scientific method includes observation, hypothesis formulation, prediction, experimentation, and conclusion.

Matter

• Anything in the universe that has mass and occupies space.
• Matter exists in various states, including solid, liquid, gas, and plasma.
• Composed of atoms, the smallest units of an element that retain its chemical properties.
• Atoms consist of a nucleus (protons and neutrons) surrounded by electrons.

Elements

• A pure substance consisting only of atoms with the same number of protons in their nuclei.
• Elements cannot be broken down into simpler substances chemically.
• Elements are arranged in the periodic table by atomic number and chemical properties.
• Examples: hydrogen (H), oxygen (O), iron (Fe), and gold (Au).

Compounds

• A substance formed when two or more elements are chemically bonded in a fixed ratio.
• The properties of a compound differ from those of its constituent elements.
• Compounds can be broken down into simpler substances by chemical reactions.
• Examples: water (H2O), table salt (NaCl), and carbon dioxide (CO2).

Mixtures

• A combination of two or more substances physically combined but not chemically bonded.
• Components retain their individual properties.
• Mixtures can be separated by physical means like filtration, evaporation, or magnetism.
• Can be homogeneous (uniform composition) or heterogeneous (non-uniform composition).
• Examples: air (gases), saltwater (salt and water), and salad (vegetables).

States of Matter

• Matter exists in four common states: solid, liquid, gas, and plasma.
• The state depends on the arrangement and behavior of constituent particles (atoms or molecules).

Solid

• Has a fixed shape and volume.
• Particles are tightly packed and held in fixed positions.
• Generally incompressible with high density.
• Examples: ice, rock, and metal.

Liquid

• Has a fixed volume but takes the shape of its container.
• Particles are close together but can move past each other.
• Relatively incompressible with moderate density.
• Examples: water, oil, and mercury.

Gas

• Has no fixed shape or volume, expands to fill its container.
• Particles are widely separated and move randomly.
• Gases are compressible with low density.
• Examples: air, oxygen, and helium.

Plasma

• A state in which a gas becomes ionized and carries an electrical charge.
• Often referred to as the fourth state of matter.
• The most common state of matter in the universe.
• Examples: lightning, stars, and the Earth's ionosphere.

Changes of State

• Matter can change states through melting, freezing, evaporation, condensation, sublimation, and deposition.
• Melting is the process of a solid changing into a liquid.
• Freezing is the reverse process of melting, where a liquid changes into a solid.
• Evaporation is the process of a liquid changing into a gas.
• Condensation is the reverse process of evaporation, where a gas changes into a liquid.
• Sublimation is the process of a solid changing directly into a gas.
• Deposition is the reverse process of sublimation, where a gas changes directly into a solid.

Properties of Matter

• Described by physical and chemical properties.

Physical Properties

• Can be observed or measured without changing the substance's chemical identity.
• Examples: color, density, melting point, boiling point, and conductivity.

Chemical Properties

• Describe how a substance reacts or changes its chemical composition.
• Examples: flammability, reactivity, and acidity.

Mass and Weight

• Mass measures the amount of matter in an object.
• Weight is the force of gravity acting on an object's mass.
• Mass is constant, but weight varies depending on the gravitational field.

Conservation of Mass

• Mass cannot be created or destroyed in a chemical reaction or physical change.
• The total mass of reactants equals the total mass of products.

Energy

• The ability to do work or transfer heat.
• Exists in forms such as kinetic, potential, thermal, chemical, and electromagnetic.

Kinetic Energy

• The energy of motion.
• Depends on the mass and velocity of an object.

Potential Energy

• Stored energy due to an object's position or condition.
• Examples: gravitational potential energy and chemical potential energy.

Thermal Energy

• Energy associated with the temperature of an object.
• Related to the kinetic energy of atoms or molecules within the object.

Chemical Energy

• Energy stored in the bonds between atoms and molecules.
• Released or absorbed during chemical reactions.

Electromagnetic Energy

• Energy that travels through space as electromagnetic waves.
• Includes radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays.