The study of chemistry primarily focuses on substances as they undergo change. You need to be able to describe the properties of substances, as well as what is happens when those properties change. Read each tab to learn about the two types of properties that substances have.
A physical property is a characteristic of a material that can be measured or observed without changing the composition of the substances in the material. For example:
This apple can be described by many physical properties, including hardness, color, mass, volume, and density. Why is each of these is a physical property of the apple?
Each of these characteristics can be measured or observed without changing the composition of the apple. You don't need to change the composition of the apple to observe that the apple is hard, and its colors are red and yellow. Additionally, you can measure its mass without changing its composition. If you had additional tools, you could also measure the volume of the apple and calculate its density.
Here's another example.
Copper has a distinct, reddish-brown color and is lustrous, which means it has a shiny appearance. It also conducts electricity very well. Additionally, copper is malleable, which means it can be bent out of shape without breaking, and ductile, which means it can be drawn into a wire. Copper melts at 1,085℃ and boils at 2,570℃.
Why are luster, conductivity, malleability, ductility, melting point, and boiling point physical properties?
Each of these characteristics can be measured or observed without changing the composition of the substance. Even melting point and boiling point are physical properties. For example, when copper melts, it changes from the solid state to the liquid state, but it's still copper. Since its composition doesn't change when it melts or boils, melting point and boiling point are physical properties.
A chemical property is the ability of a substance to change into one or more new substances. Chemical properties can be measured or observed only by changing the composition of the substance. The change can be the result of its contact with another substance or the application of energy.
One of the main chemical properties of matter is reactivity. Reactivity is the property that describes how readily a substance chemically combines with another substance. Oxygen is a very reactive element. Oxygen readily reacts with most other elements to form compounds. For example:
The Statue of Liberty is made of copper, which is an element with a reddish-brown color. The statue has turned green because of copper's tendency to oxidize, or react with oxygen. Due to oxidation, the copper (Cu) has changed into a new substance called copper oxide (CuO).
Iron has a similar tendency for oxidation, which we call rusting. When iron rusts, it reacts with oxygen to form a reddish-brown compound. The ability of iron to form rust when combined with oxygen is an example of a chemical property of iron.
When a metal is worn away by this type of reaction, it corrodes. Corrosion is the loss of metal resulting from a reaction of a metal with substances in the environment.
How do we know that the ability of a substance to oxidize is a chemical property?
Oxidation can only be observed if the substance has changed composition because of its contact with oxygen. Since oxidation can only be observed by changing the composition of the substance, the ability of a substance to oxidize is a chemical property.
A chemical property of a substance can be observed when the chemical composition of the substance changes. The change can be the result of its contact with another substance or the application of energy. The other main chemical property of matter is flammability. Flammability is the ability of a material to catch fire and burn. For example:
Gasoline is a flammable material, and its vapors are very combustible (they catch fire easily). Otherwise, gasoline is not a very reactive substance, meaning it does not readily react with other substances.
What chemical property does paper share with gasoline?
The chemical property that paper shares with gasoline is flammability. Both gasoline and paper can catch fire and burn.
Let's Practice
How well can you differentiate between physical and chemical properties? Find out by completing this activity. Select the correct answer to each question.
Properties
1. Which statement describes a physical property?
Silver is a shiny metal.
Iron metal can rust (oxidize).
Chromium metal does not oxidize.
Physical properties can be measured or observed without changing the composition of the substances in the material. You can observe a material's appearance without changing its composition. But you cannot determine that a substance is capable of oxidizing unless the substance has changed composition as a result of its contact with oxygen.
Physical properties can be measured or observed without changing the composition of the substances in the material. You can observe a material's appearance without changing its composition. But you cannot determine that a substance is capable of oxidizing unless the substance has changed composition as a result of its contact with oxygen.
Physical properties can be measured or observed without changing the composition of the substances in the material. You can observe a material's appearance without changing its composition. But you cannot determine that a substance is capable of oxidizing unless the substance has changed composition as a result of its contact with oxygen.
2. Which statement describes a chemical property?
Mercury is a very dense liquid.
Gallium metal melts at 30℃.
Sodium reacts with water.
Chemical properties can be measured or observed only by changing the composition of the substance. Observing whether a substance will react with another substance is only possible by putting it in contact with the other substance to observe any change in the chemical make-up of the original substance. But describing a material's density or identifying its melting point can be done without changing the composition of the substance.
Chemical properties can be measured or observed only by changing the composition of the substance. Observing whether a substance will react with another substance is only possible by putting it in contact with the other substance to observe any change in the chemical make-up of the original substance. But describing a material's density or identifying its melting point can be done without changing the composition of the substance.
3. Which statement describes a physical property?
Paper can burn.
Sandpaper has a rough texture.
Left out for too long, an apple will rot.
Physical properties can be measured or observed without changing the composition of the substances in the material. Describing a material's texture does not change the chemical composition of the substances in the material. But observing whether something can burn or rot would require a change in the chemical make-up of the material.
Physical properties can be measured or observed without changing the composition of the substances in the material. Describing a material's texture does not change the chemical composition of the substances in the material. But observing whether something can burn or rot would require a change in the chemical make-up of the material.
Physical properties can be measured or observed without changing the composition of the substances in the material. Describing a material's texture does not change the chemical composition of the substances in the material. But observing whether something can burn or rot would require a change in the chemical make-up of the material.
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