Unformatted text preview: 9/11/21, 11:42 PM Classification of Matter | Boundless Chemistry Boundless Chemistry
Introduction to Chemistry Classification of Matter 1/17 9/11/21, 11:42 PM Classification of Matter | Boundless Chemistry Three States of Matter
The three states of matter are the distinct physical forms that matter can
take: solid, liquid, and gas. LEARNING OBJECTIVES Describe the three states of matter KEY TAKEAWAYS Key Points Matter can exist in one of three main states: solid, liquid,
Solid matter is composed of tightly packed particles. A
solid will retain its shape; the particles are not free to
Liquid matter is made of more loosely packed particles.
It will take the shape of its container. Particles can move
about within a liquid, but they are packed densely
enough that volume is maintained.
Gaseous matter is composed of particles packed so
loosely that it has neither a defined shape nor a defined
volume. A gas can be compressed.
Key Terms liquid: A substance that flows and keeps no definite shape because its molecules are loosely packed and
constantly moving. It takes the shape of its container
but maintains constant volume. 2/17 9/11/21, 11:42 PM Classification of Matter | Boundless Chemistry gas: A substance that can only be contained if it is fully surrounded by a container (or held together by gravitational pull); a substance whose molecules have negligible intermolecular interactions and can move freely.
solid: A substance that retains its size and shape with- out a container; a substance whose molecules cannot
move freely except to vibrate. The three states of matter are the three distinct physical forms that matter can take in most environments: solid, liquid, and gas. In extreme environments, other states may be present, such as plasma, Bose-Einstein
condensates, and neutron stars. Further states, such as quark-gluon
plasmas, are also believed to be possible. Much of the atomic matter of
the universe is hot plasma in the form of rarefied interstellar medium and
Historically, the states of matter were distinguished based on qualitative
differences in their bulk properties. Solid is the state in which matter
maintains a fixed volume and shape; liquid is the state in which matter
adapts to the shape of its container but varies only slightly in volume;
and gas is the state in which matter expands to occupy the volume and
shape of its container. Each of these three classical states of matter can
transition directly into either of the other two classical states. The states of matter: This diagram shows the nomenclature for the different
phase transitions. Solids
A solid’s particles are packed closely together. The forces between the 3/17 9/11/21, 11:42 PM Classification of Matter | Boundless Chemistry particles are strong enough that the particles cannot move freely; they
can only vibrate. As a result, a solid has a stable, definite shape and a
definite volume. Solids can only change shape under force, as when broken or cut.
In crystalline solids, particles are packed in a regularly ordered, repeating pattern. There are many different crystal structures, and the same
substance can have more than one structure. For example, iron has a
body-centered cubic structure at temperatures below 912 °C and a facecentered cubic structure between 912 and 1394 °C. Ice has fifteen known
crystal structures, each of which exists at a different temperature and
A solid can transform into a liquid through melting, and a liquid can
transform into a solid through freezing. A solid can also change directly
into a gas through a process called sublimation. Liquids
A liquid is a fluid that conforms to the shape of its container but that retains a nearly constant volume independent of pressure. The volume is
definite (does not change) if the temperature and pressure are constant.
When a solid is heated above its melting point, it becomes liquid because the pressure is higher than the triple point of the substance.
Intermolecular (or interatomic or interionic) forces are still important, but
the molecules have enough energy to move around, which makes the
structure mobile. This means that a liquid is not definite in shape but
rather conforms to the shape of its container. Its volume is usually
greater than that of its corresponding solid (water is a well-known exception to this rule). The highest temperature at which a particular liquid can
exist is called its critical temperature.
A liquid can be converted to a gas through heating at constant pressure
to the substance’s boiling point or through reduction of pressure at constant temperature. This process of a liquid changing to a gas is called
evaporation. Gases 4/17 9/11/21, 11:42 PM Classification of Matter | Boundless Chemistry Gas molecules have either very weak bonds or no bonds at all, so they
can move freely and quickly. Because of this, not only will a gas conform
to the shape of its container, it will also expand to completely fill the container. Gas molecules have enough kinetic energy that the effect of intermolecular forces is small (or zero, for an ideal gas), and they are spaced
very far apart from each other; the typical distance between neighboring
molecules is much greater than the size of the molecules themselves.
A gas at a temperature below its critical temperature can also be called
a vapor. A vapor can be liquefied through compression without cooling.
It can also exist in equilibrium with a liquid (or solid), in which case the
gas pressure equals the vapor pressure of the liquid (or solid).
A supercritical fluid (SCF) is a gas whose temperature and pressure are
greater than the critical temperature and critical pressure. In this state,
the distinction between liquid and gas disappears. A supercritical fluid
has the physical properties of a gas, but its high density lends it the
properties of a solvent in some cases. This can be useful in several applications. For example, supercritical carbon dioxide is used to extract
caffeine in the manufacturing of decaffeinated coffee. Phase Changes Phase Changes: What does a phase change look like at the molecular level? This video takes a look at the molecular structure of solids, liquids,
and gases and examines how the kinetic energy of the particles 5/17 9/11/21, 11:42 PM Classification of Matter | Boundless Chemistry changes. The video also discusses melting, vaporization, condensation,
and freezing. Substances and Mixtures
Substances are composed of pure elements or chemically bonded elements, whereas mixtures are composed of non-bonded substances. LEARNING OBJECTIVES Distinguish chemical substances from mixtures KEY TAKEAWAYS Key Points Matter can be broken down into two categories: pure
substances and mixtures. Pure substances are further
broken down into elements and compounds. Mixtures
are physically combined structures that can be separated into their original components.
A chemical substance is composed of one type of atom
A mixture is composed of different types of atoms or
molecules that are not chemically bonded.
A heterogeneous mixture is a mixture of two or more
chemical substances where the various components
can be visually distinguished.
A homogeneous mixture is a type of mixture in which
the composition is uniform and every part of the solution has the same properties. 6/17 9/11/21, 11:42 PM Classification of Matter | Boundless Chemistry Various separation techniques exist in order to separate
matter, including include distillation, filtration, evaporation and chromatography. Matter can be in the same
phase or in two different phases for this separation to
Key Terms mixture: Something that consists of diverse, non- bonded elements or molecules.
element: A chemical substance that is made up of a particular kind of atom and cannot be broken down or
transformed by a chemical reaction.
substance: A form of matter that has constant chemical composition and characteristic properties. It is composed of one type of atom or molecule. Chemical Substances
In chemistry, a chemical substance is a form of matter that has constant
chemical composition and characteristic properties. It cannot be separated into components without breaking chemical bonds. Chemical substances can be solids, liquids, gases, or plasma. Changes in temperature
or pressure can cause substances to shift between the different phases
An element is a chemical substance that is made up of a particular kind
of atom and hence cannot be broken down or transformed by a chemical reaction into a different element. All atoms of an element have the
same number of protons, though they may have different numbers of
neutrons and electrons.
A pure chemical compound is a chemical substance that is composed of
a particular set of molecules or ions that are chemically bonded. Two or
more elements combined into one substance through a chemical reaction, such as water, form a chemical compound. All compounds are substances, but not all substances are compounds. A chemical compound 7/17 9/11/21, 11:42 PM Classification of Matter | Boundless Chemistry can be either atoms bonded together in molecules or crystals in which
atoms, molecules or ions form a crystalline lattice. Compounds made primarily of carbon and hydrogen atoms are called organic compounds,
and all others are called inorganic compounds. Compounds containing
bonds between carbon and a metal are called organometallic
Chemical substances are often called ‘pure’ to set them apart from mixtures. A common example of a chemical substance is pure water; it always has the same properties and the same ratio of hydrogen to oxygen
whether it is isolated from a river or made in a laboratory. Other chemical
substances commonly encountered in pure form are diamond (carbon),
gold, table salt (sodium chloride), and refined sugar (sucrose). Simple or
seemingly pure substances found in nature can in fact be mixtures of
chemical substances. For example, tap water may contain small amounts
of dissolved sodium chloride and compounds containing iron, calcium,
and many other chemical substances. Pure distilled water is a substance,
but seawater, since it contains ions and complex molecules, is a mixture. Chemical Mixtures
A mixture is a material system made up of two or more different substances, which are mixed but not combined chemically. A mixture refers
to the physical combination of two or more substances in which the
identities of the individual substances are retained. Mixtures take the
form of alloys, solutions, suspensions, and colloids. 8/17 9/11/21, 11:42 PM Classification of Matter | Boundless Chemistry Naturally occurring sulfur crystals: Sulfur occurs naturally as elemental
sulfur, sulfide, and sulfate minerals and in hydrogen sulfide. This mineral
deposit is composed of a mixture of substances. Heterogeneous Mixtures
A heterogeneous mixture is a mixture of two or more chemical substances (elements or compounds), where the different components can
be visually distinguished and easily separated by physical means.
mixtures of sand and water
mixtures of sand and iron filings
a conglomerate rock
water and oil
mixtures of gold powder and silver powder 9/17 9/11/21, 11:42 PM Classification of Matter | Boundless Chemistry Separa Shake up the oil and water mixture Interactive: Oil and Water: Explore the interactions that cause water and oil to separate from a mixture. Homogenous Mixtures
A homogeneous mixture is a mixture of two or more chemical substances (elements or compounds), where the different components cannot be visually distinguished. Often separating the components of a homogeneous mixture is more challenging than separating the components of a heterogeneous mixture.
Distinguishing between homogeneous and heterogeneous mixtures is a
matter of the scale of sampling. On a small enough scale, any mixture
can be said to be heterogeneous, because a sample could be as small
as a single molecule. In practical terms, if the property of interest is the 10/17 9/11/21, 11:42 PM Classification of Matter | Boundless Chemistry same regardless of how much of the mixture is taken, the mixture is
A mixture’s physical properties, such as its melting point, may differ from
those of its individual components. Some mixtures can be separated into
their components by physical (mechanical or thermal) means. Chemistry 1.2 Classifying Ma…
Ma… Chemistry 1.2 Classifying Ma…
Ma… 11/17 9/11/21, 11:42 PM Classification of Matter | Boundless Chemistry Chemistry 1.2 Classifying Ma…
Ma… Classifying Matter (3 parts): Introduction to classifying matter as a sub- stance or a mixture of substances. Mixtures are described as heterogeneous or homogeneous. Three common methods of separation are
described. Elements and Compounds
An element is a material that consists of a single type of atom, while a
compound consists of two or more types of atoms. LEARNING OBJECTIVES Differentiate between elements and compounds and explore
separation techniques KEY TAKEAWAYS Key Points Elements are the simplest complete chemical substances. Each element corresponds to a single entry on 12/17 9/11/21, 11:42 PM Classification of Matter | Boundless Chemistry the periodic table. An element is a material that consists
of a single type of atom. Each atom type contains the
same number of protons.
Chemical bonds link elements together to form more
complex molecules called compounds. A compound
consists of two or more types of elements held together
by covalent or ionic bonds.
Elements cannot be divided into smaller units without
large amounts of energy. Compounds, on the other
hand, can have their bonds broken with practical
amounts of energy, such as the heat from a fire.
Matter can be broken down into two categories: pure
substances and mixtures. Pure substances are further
broken down into elements and compounds. Mixtures
are physically combined structures that can be separated back into their original components.
Key Terms element: Any one of the simplest chemical substances that cannot be changed in a chemical reaction or by
any chemical means. Made up of atoms that all have the
same number of protons.
chemical bond: Any of several attractive forces that serve to bind atoms together to form molecules.
compound: A substance made from two or more ele- ments. Consists of a fixed ratio of chemically bonded
atoms. Has unique properties that are different from the
properties of its individual elements. Elements
A chemical element is a pure substance that consists of one type of
atom. Each atom has an atomic number, which represents the number of
protons that are in the nucleus of a single atom of that element. The periodic table of elements is ordered by ascending atomic number. 13/17 9/11/21, 11:42 PM Classification of Matter | Boundless Chemistry The chemical elements are divided into the metals, the metalloids, and
the non-metals. Metals, typically found on the left side of the periodic table, are:
often conductive to electricity
Aluminum, iron, copper, gold, mercury and lead are metals.
In contrast, non-metals, found on the right side of the periodic table (to
the right of the staircase), are:
typically not conductive
dull (not shiny)
Examples of elemental non-metals include carbon and oxygen.
Metalloids have some characteristics of metals and some characteristics
of non-metals. Silicon and arsenic are metalloids.
As of November, 2011, 118 elements have been identified (the most recently identified was ununseptium, in 2010). Of these 118 known elements, only the first 98 are known to occur naturally on Earth. The elements that do not occur naturally on Earth are the synthetic products of
man-made nuclear reactions. 80 of the 98 naturally-occurring elements
are stable; the rest are radioactive, which means they decay into lighter
elements over timescales ranging from fractions of a second to billions
The periodic table: The periodic table shows 118 elements, including metals 14/17 9/11/21, 11:42 PM Classification of Matter | Boundless Chemistry (blue), nonmetals (red), and metalloids (green). Hydrogen and helium are by far the most abundant elements in the universe. However, iron is the most abundant element (by mass) in the composition of the Earth, and oxygen is the most common element in the
layer that is the Earth’s crust.
Although all known chemical matter is composed of these elements,
chemical matter itself constitutes only about 15% of the matter in the universe. The remainder is dark matter, a mysterious substance that is not
composed of chemical elements. Dark matter lacks protons, neutrons, or
Pure samples of isolated elements are uncommon in nature. While the
98 naturally occurring elements have all been identified in mineral samples from the Earth’s crust, only a small minority of them can be found as
recognizable, relatively pure minerals. Among the more common of such
“native elements” are copper, silver, gold, and sulfur. Carbon is also commonly found in the form of coal, graphite, and diamonds. The noble
gases (e.g., neon) and noble metals (e.g., mercury) can also be found in
their pure, non-bonded forms in nature. Still, most of these elements are
found in mixtures.
When two distinct elements are chemically combined—i.e., chemical
bonds form between their atoms—the result is called a chemical compound. Most elements on Earth bond with other elements to form chemical compounds, such as sodium (Na) and Chloride (Cl), which combine to
form table salt (NaCl). Water is another example of a chemical compound. The two or more component elements of a compound can be
separated through chemical reactions.
Chemical compounds have a unique and defined structure, which consists of a fixed ratio of atoms held together in a defined spatial arrangement by chemical bonds. Chemical compounds can be:
molecular compounds held together by covalent bonds 15/17 9/11/21, 11:42 PM Classification of Matter | Boundless Chemistry salts held together by ionic bonds
intermetallic compounds held together by metallic bonds
complexes held together by coordinate covalent bonds.
Pure chemical elements are not considered chemical compounds, even
View Full Document