I'm thinking of an object you might have at home. Can you guess it?

Clip from Sesame Street. Amanda Seyfried looks up from a book and says,

I can hold it in one hand.

A hand catching a Lego minifigure in a space suit. Photo by Nik on Unsplash

It's yellow.

A bike parked on concrete in front of a yellow wall. Photo by Alexey Lin on Unsplash

Its juice is acidic.

Toddler takes a sip from a cup with a straw and makes a sour face, tossing their head back.

Did you guess it?

It's a lemon!

Photo by Auguste A on Unsplash Photo by Auguste A on Unsplash

You might not realize it, but you used some of the lemon's physical and chemical properties to identify it.

Learn a little more about these key properties of materials to help you succeed in science class.

Physical Properties of Materials

A physical property of an object can be seen or measured without changing the object's identity.

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Some examples are:

  • Length

  • Density

  • Mass

  • Temperature

  • Luster (shine)

Lemon icon.

Returning to our lemon example, we could measure the length of the lemon at 7.5 cm without changing anything about the lemon itself.

To get more specific, physical properties are divided into two groups: intensive and extensive.

Intensive and Extensive Properties of Materials

Intensive Properties

  • Don't depend on the size of the sample.


  • Temperature

  • Density

  • Color

  • Odor/smell

Extensive Properties

  • Do depend on the size of the sample.


  • Size

  • Length

  • Volume

  • Mass (weight)

Lemon icon.

Whether we have a whole lemon or a small wedge, it will still smell like lemon. The smell is an intensive property because it's the same whether the piece of lemon is big or small.

A wedge of lemon weighs less than a whole lemon does. This extensive property changes when the samples are of different sizes.

Chemical Properties of Materials

When you observe or test an object's chemical properties, the molecules that make up the object change.

A scene from Turning Red where a young girl turns into a giant red panda in her bedroom.

Some examples of chemical properties include:

  • Being acidic or basic

  • Flammability

  • Reactivity at room temperature — whether it will react with water or air at typical temperatures

  • Oxidation — the ability to react with oxygen

Lemon icon.

Our lemon can oxidize. If we leave it on the counter for days, it will react with oxygen and turn brown.


Which of these is a chemical property?

Physical Changes

When you're trying to understand the chemical and physical properties of materials, discussing the changes to those properties can be helpful.

When you make a physical change to an object, its chemical composition stays the same, but something about its size or appearance changes.

Lemon icon. Some physical changes we could make to our lemon are:

  • Color — paint it blue 🎨

  • Size — chop it in half 🔪

  • Temperature — cool it in the refrigerator 🌡️

A knife slicing into a whole lemon, with another half lemon leaning on it. Photo by John Vid on Unsplash

The lemon is still a lemon after all these changes. It hasn't become something new. That's how we know the properties we changed are physical, not chemical.

Chemical Changes

Chemical changes result in new substances. Chemical properties of materials are affected by chemical changes. If you're trying to identify a chemical property of an object, it might be easier to think about how changing the property would affect the material.

Lemon icon.

Some chemical changes we could make to the lemon are:

  • Burning — lighting it on fire produces ash, water, and carbon dioxide.

  • Oxidation — letting the lemons react with air to become soft and brown.

  • Fermenting — making preserved lemons, similar to pickling.

Looking into a big jar full of sliced lemons on a countertop. Photo by Jozsef Hocza on Unsplash

Chemical changes can't often be reversed. New substances have formed from the original lemon.


We've made a lot of changes to our lemon!

A character from Schitt's Creek says,

Let's review:

Physical Properties

  • Observed without changing the material

  • Can be intensive (don't depend on sample size) or extensive (depend on sample size)

  • Include size, mass, density, temperature

Chemical Properties

  • Testing them changes the chemical makeup of the object

  • Aren't easily reversed

  • Include flammability, oxidation, reaction with acid or base

Check Your Understanding

Flaticon Icon

Devon is trying to figure out the physical and chemical properties of a wooden log they found in their shed by doing different tests. Could you identify the chemical properties that Devon tested? How they tried each is noted in parentheses.


Identify the chemical properties:

Take Action

A man pours liquids from two small beakers into a larger tall container. Quickly the reaction foams, shooting up.

Now, that's a chemical change for ya!

Apply what you learned about physical and chemical properties of materials:


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