Properties of Matter

Dictionary definitions of chemistry usually include the terms matter,composition, and properties, as in the statement that chemistry is the science that deals with the composition and properties of matter.Matter is anything that occupies space and displays the properties of mass
and inertia. Every human being is a collection of matter. We all occupy space,and we describe our mass in terms of weight, a related property.All the objects that we see around us consist of matter.The gases of the atmosphere, even though they are invisible, are matter they occupy space and have mass. Sunlight is not matter; rather, it is a form of energy.Composition refers to the parts or components of a sample of matter
and their relative proportions. Ordinary water is made up of two simpler substances hydrogen and oxygen present in certain fixed proportions.A chemist would say that the composition of water is 11.19% hydrogen and 88.81% oxygen by mass. Hydrogen peroxide, a substance used in bleaches and antiseptics, is also made up of hydrogen and oxygen, but it has a different composition. Hydrogen peroxide is 5.93% hydrogen and 94.07% oxygen by mass.Properties are those qualities or attributes that we can use to distinguish one
sample of matter from others; and, as we consider next, the properties of matter are generally grouped into two broad categories: physical and chemical.
Physical Properties and Physical Changes
A physical property is one that a sample of matter displays without changing its composition. Thus, we can distinguish between the reddish brown solid,copper, and the yellow solid, sulfur, by the physical property of color .Another physical property of copper is that it can be hammered into a thin sheet of foil. Solids having this ability are said to be malleable.Sulfur is not malleable. If we strike a chunk of sulfur with a hammer, it crumbles into a powder. Sulfur is brittle. Another physical property of copper that sulfur does not share is the ability to be drawn into a fine wire (ductility). Also,sulfur is a far poorer conductor of heat and electricity than is copper.Sometimes a sample of matter undergoes a change in its physical appearance.In such a physical change, some of the physical properties of the sample may change, but its composition remains unchanged. When liquid water freezes into solid water (ice), it certainly looks different and, in many ways, it is different. Yet, the water remains 11.19% hydrogen and 88.81% oxygen by mass.
Chemical Properties and Chemical Changes
In a chemical change, or chemical reaction, one or more kinds of matter are converted to new kinds of matter with different compositions. The key to identifying chemical change, then, comes in observing a change in composition. The burning of paper involves a chemical change. Paper is a complex material,
but its principal constituents are carbon, hydrogen, and oxygen. The chief products of the combustion are two gases, one consisting of carbon and oxygen (carbon dioxide) and the other consisting of hydrogen and oxygen (water, as steam). The ability of paper to burn is an example of a chemical property. A chemical property is the ability (or inability) of a sample of matter to undergo
a change in composition under stated conditions