4.1: States of Matter
- Page ID
- 498392
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)- Describe the properties of the solids, liquids, and gases
The three common phases (or states) of matter are gases, liquids, and solids.
Gases have the lowest density of the three states. They are highly compressible and expand to completely fill any container. Because the intermolecular forces in gases are weak compared to the kinetic energy of the particles, the particles move freely and remain far apart from one another.
Solids, in contrast, are dense, rigid, and incompressible. Their strong intermolecular forces keep the particles locked in fixed positions, allowing only slight vibrations. As a result, solids maintain a definite shape and volume.
Liquids share some characteristics of both solids and gases. Like solids, they are dense and incompressible, but unlike solids, their particles can move past one another, allowing them to flow and take the shape of their container. The strength of the intermolecular forces relative to the kinetic energy in liquids is stronger than in gases but weaker than in solids. As a result, liquid particles remain close together, they are not fixed in place.
Figure \(\PageIndex{1}\) illustrates the molecular differences between gases, liquids and solids using oxygen, O2, as an example:
Figure \(\PageIndex{1}\): O2 in the Solid, Liquid, and Gaseous States: (a) Solid oxygen has a fixed shape and volume, with its molecules packed tightly together. (b) Liquid oxygen takes the shape of its container but maintains a fixed volume, with its molecules remaining relatively close to one another. (c) Gaseous oxygen expands to fill any container and consists of widely separated molecules that move independently.
The physical state of a substance depends on temperature and pressure. Water is a familiar example of a substance that exists in all three states under everyday conditions. Solid water, or ice, is found in snow, ice cubes, and glaciers. Liquid water is the most common and essential form, present in lakes, rivers, and oceans, as well as in drinking water. Water also exists as a gas, known as water vapor, which is part of the air we breathe and forms when water evaporates, such as from boiling water or drying clothes.
Although the individual water molecules (H2O) are identical in all states, the macroscopic properties of water, such as density, volume and compressibility, depend on interactions between molecules (intermolecular forces) and external conditions, such as temperature and pressure.
For your interest, Figure \(\PageIndex{2}\) shows elements commonly found in the gaseous, liquid, and solid states at 25°C and 1.0 atm. . Except for hydrogen, the elements that occur naturally as gases are on the right side of the periodic table. The noble gases (group 18) exist as monatomic gases, while the other gaseous elements, hydrogen, nitrogen, oxygen, fluorine, and chlorine, are diatomic molecules. Oxygen can also form a second allotrope, ozone (O3), a highly reactive triatomic gas. In contrast, bromine (Br2) and mercury (Hg) are liquids at 25°C and 1.0 atm. The remaining elements are all solids under these conditions.
Summary
Matter exists in three states: gas, liquid, and solid. Gas particles are far apart, making gases highly compressible. Gases expand to fill their container. Liquid particles are close together, making liquids dense and relatively incompressible, but they can move past each other, allowing liquids to take the shape of their container. The particles of solids are close together and vibrate in fixed positions, making solids dense, rigid, and incompressible.
The physical state of a substance depends on the balance between intermolecular forces and the kinetic energy of the particles, which is determined by both temperature and pressure.