Question

Which physical state is described as having particles closely packed and held rigidly in position?

Short answer

The solid state is described by closely packed particles held rigidly in position.

Step-by-step solution

Identify Keyword

The keyword in the exercise is "particles closely packed and held rigidly in position." This describes the arrangement of particles in one of the common physical states of matter.

Define Solid State

In the solid state, particles are closely packed in a fixed position and maintain a definite shape and volume. This rigid arrangement is due to strong intermolecular forces.

Compare with Other States

In contrast, particles in liquid and gaseous states are not held rigidly in place. Liquids have particles that are close but can move around each other, and gases have particles that are much farther apart and move freely.

Key concepts

Physical States of Matter

Matter can exist in different forms, each with distinct characteristics. These forms are known as the physical states of matter, traditionally categorized into three primary types: solid, liquid, and gas. Each state can be identified by the behavior and arrangement of its particles, as well as how they interact with one another.

In a solid state, particles are arranged closely together in a fixed and orderly pattern. This allows solids to maintain a specific shape and volume, unlike liquids and gases. Liquids have particles that, while still in proximity, can slide past each other, enabling them to adapt their shape to the container they are in while maintaining a consistent volume. Gases, on the other hand, have particles that are widely spaced and move freely, filling the available volume of their container. Understanding these basic characteristics helps clarify why solids are firm and rigid, while liquids and gases are more fluid.

Recognizing the different states of matter and their unique properties helps in categorizing how materials behave in various environments.

Particle Arrangement

The arrangement of particles in a substance greatly influences its state and properties. In solids, particles are tightly packed in an orderly, repeating pattern known as a crystal lattice. This arrangement leads to defined shapes and structures, contributing to the solidity and incompressibility of the material.

In liquids, while particles are still close to one another, they lack the fixed structure seen in solids. This allows for fluid motion, enabling the liquid to take the shape of its container while resisting compressibility. Liquids have more space between particles compared to solids, but less than gases.

Gases are characterized by a significant distance between particles, resulting in no fixed shape or volume. The particles in a gas move rapidly and freely, spreading to uniformly fill any container they're in. Particle arrangement is a fundamental concept in understanding the transition between these states, such as melting and freezing, where the structure changes from ordered to less ordered, and vice versa.

Intermolecular Forces

Intermolecular forces are the forces that hold molecules together within a substance. These forces are pivotal in determining a material's physical properties, such as its state of matter. They are generally stronger in solids, moderate in liquids, and weakest in gases.

In the solid state, the intermolecular forces are strong enough to keep particles locked in place, forming a rigid structure that retains its shape and volume under normal conditions. This makes solids the most stable of the three states.

In liquids, intermolecular forces are weaker than in solids, allowing particles to flow past each other while remaining close. This results in a state that is both fluid and somewhat compressible while maintaining a constant volume.

Gases exhibit very weak intermolecular forces, which is why their particles are far apart and move independently. This lack of binding force lets gases easily expand to fill any container. Understanding these forces provides insights into how substances change state through processes like evaporation, condensation, melting, and freezing, as these transitions involve changes in intermolecular forces.