How is matter identified

When substances change state, it is because the spacing between the particles of the substances is changing due to a gain or loss of energy. For example, we all have probably observed that water can exist in three forms with different characteristic ways of behaving: the solid state ice , liquid state water , and gaseous state water vapor and steam.

Due to water's prevalence, we use it to exemplify and describe the three different states of matter. As ice is heated and the particles of matter that make up water gain energy, eventually the ice melts in to water that eventually boils and turns into steam. Before we examine the states of matter, we will consider some ways samples of matter have been classified by those who have studied how matter behaves.

Evidence suggests that substances are made up of smaller particles that are ordinarily moving around. Some of those particles of matter can be split into smaller units using fairly strong heat or electricity into smaller rather uniform bits of matter called atoms. Atoms are the building blocks of elements.

Elements are all those substances that have not ever been decomposed or separated into any other substances through chemical reactions, by the application of heat, or by attempting to force an direct electric current through the sample.

Atoms in turn have been found to be made up of yet smaller units of matter called electrons, protons, and neutrons. Elements can be arranged into what is called the periodic table of elements based on observed similarities in chemical and physical properties among the different elements. When atoms of two or more elements come together and bond, a compound is formed. The compound formed can later be broken down into the pure substances that originally reacted to form it.

Compounds such as water are composed of smaller units of bonded atoms called molecules. Molecules of a compound are composed of the same proportion of elements as the compound as a whole since they are the smallest units of that compound. For example, every portion of a sample of water is composed of water molecules.

Each water molecule contains two hydrogen atoms and one oxygen atom, and so water as a whole has, in a combined state, twice as many hydrogen atoms as oxygen atoms.. Water can still consist of the same molecules, but its physical properties may change.

When matter changes from one state to another, temperature and pressure may be involved in the process and the density and other physical properties change. The temperature and pressure exerted on a sample of matter determines the resulting form of that the matter takes, whether solid, liquid, or gas. Since the properties of compounds and elements are uniform, they are classified as substances. When two or more substances are mixed together, the result is called a mixture.

Mixtures can be classified into two main categories: homogeneous and heterogeneous. A homogeneous mixture is one in which the composition of its constituents are uniformly mixed throughout. A homogeneous mixture in which on substance, the solute, dissolves completely in another substance, the solvent, may also be called a solution. Usually the solvent is a liquid, however the solute can be either a liquid, solid, or a gas.

In a homogeneous solution, the particles of solute are spread evenly among the solvent particles and the extremely small particles of solute cannot be separated from the solvent by filtration through filter paper because the spaces between paper fibers are much greater than the size of the solute and solvent particles. Other examples of homogeneous mixtures include sugar water, which is the mixture of sucrose and water, and gasoline, which is a mixture of dozens of compounds.

Homogeneous Mixtures: Filtered seawater is solution of the compounds of water, salt sodium chloride , and other compounds. Currently, about elements are known, but millions of chemical compounds have been prepared from these elements.

The known elements are listed in the periodic table. In general, a reverse chemical process breaks down compounds into their elements. For example, water a compound can be decomposed into hydrogen and oxygen both elements by a process called electrolysis. A similar technique is used on a vast scale to obtain pure aluminum, an element, from its ores, which are mixtures of compounds. Because a great deal of energy is required for electrolysis, the cost of electricity is by far the greatest expense incurred in manufacturing pure aluminum.

Thus recycling aluminum is both cost-effective and ecologically sound. Identify each substance as a compound, an element, a heterogeneous mixture, or a homogeneous mixture solution. Matter can be classified according to physical and chemical properties. Matter is anything that occupies space and has mass. The three states of matter are solid, liquid, and gas.

A physical change involves the conversion of a substance from one state of matter to another, without changing its chemical composition. Most matter consists of mixtures of pure substances, which can be homogeneous uniform in composition or heterogeneous different regions possess different compositions and properties. Pure substances can be either chemical compounds or elements. Compounds can be broken down into elements by chemical reactions, but elements cannot be separated into simpler substances by chemical means.

The properties of substances can be classified as either physical or chemical. Scientists can observe physical properties without changing the composition of the substance, whereas chemical properties describe the tendency of a substance to undergo chemical changes chemical reactions that change its chemical composition.

Physical properties can be intensive or extensive. Intensive properties are the same for all samples; do not depend on sample size; and include, for example, color, physical state, and melting and boiling points. Extensive properties depend on the amount of material and include mass and volume.

The ratio of two extensive properties, mass and volume, is an important intensive property called density. Modified by Joshua Halpern Howard University.

Learning Objectives To classify matter. Pure Substances and Mixtures A pure chemical substance is any matter that has a fixed chemical composition and characteristic properties. Under a microscope, whole milk is actually a heterogeneous mixture composed of globules of fat and protein dispersed in water. Figure used with permission from Wikipedia Homogeneous mixtures solutions can be separated into their component substances by physical processes that rely on differences in some physical property, such as differences in their boiling points.

Define compound. How does it differ from an element? Identify each substance as an element, a compound, a heterogeneous mixture, or a solution. Identify each material as an element, a compound, a heterogeneous mixture, or a solution. An element is a substance that cannot be broken down into chemically simpler components.

Compounds can be broken down into simpler substances. Privacy Policy. Skip to main content. Chapter 1: Chemistry, Matter, and Measurement. Search for:. Identify a sample of matter as an element, a compound, or a mixture. Physical and Chemical Properties. Elements and Compounds Any sample of matter that has the same physical and chemical properties throughout the sample is called a substance.

Note Sometimes the word pure is added to substance, but this is not absolutely necessary. Mixtures A material composed of two or more substances is a mixture. Example How would a chemist categorize each example of matter? Saltwater is a homogeneous mixture, or a solution. Soil is composed of small pieces of a variety of materials, so it is a heterogeneous mixture.

Water is a substance; more specifically, because water is composed of hydrogen and oxygen, it is a compound. Oxygen, a substance, is an element. Skill-Building Exercise How would a chemist categorize each example of matter? Table 1. Concept Review Exercises Explain the differences between the physical properties of matter and the chemical properties of matter. Physical properties are properties we can observe without changing the composition makeup of a substance.

Recall that molecules are made when atoms of the same or different elements react. For example, a molecule of water has the chemical formula H 2 O, and it is made when molecules of oxygen react with molecules of hydrogen. So the physical properties of water are those properties that can be observed without splitting the water molecule into hydrogen and oxygen atoms.