Matter and Things That Are Not Matter

Introduction

Some things in our world are obviously real but are not made of matter at all. A rainbow, a musical note, the warmth of a fire and a good idea all exist, yet none of them can be put into a jar and weighed. Learning to separate matter from things that are not matter is one of the first skills of a chemist, because chemistry deals with the stuff itself and with the energy changes that accompany its changes.

Core explanation

Energy is not matter. Energy is the ability to cause change. It comes in many forms — light, heat (thermal energy), sound, electrical energy, kinetic energy of movement — and it can be transferred from one object to another. Energy has no particles of its own, it does not occupy space in the way a solid, liquid or gas does, and adding energy to a sealed jar does not make it measurably heavier.

Light. Light is electromagnetic radiation. It can travel through empty space (which is how sunlight reaches Earth), and two beams can cross without bumping into each other. Light can be absorbed by matter, which warms it, but light itself is not a substance.

Sound. Sound is energy carried by vibrations. It needs matter to travel through — air, water or a solid — because it is passed along as particles push on their neighbours. In the vacuum of space there is no sound. The air is matter; the sound is the energy moving through it.

Heat. Heat is energy transferred because of a temperature difference. Historically scientists believed heat was an invisible fluid called "caloric", but careful experiments in the 1700s and 1800s showed that heating an object does not change its mass. Heat is now understood as energy transfer, and temperature as a measure of how fast particles are moving.

Other non-matter. Shadows (an absence of light), electric and magnetic fields, time, thoughts, feelings and information are also not matter. A book is matter; the story in it is not.

Why chemistry needs both. Every chemical change involves matter being rearranged and energy being transferred: a candle burns (matter changes into carbon dioxide and water) and gives out light and heat (energy). Keeping the two ideas separate helps you describe reactions correctly.

Step-by-step reasoning

For any item, work through these checks:

1. Can it be collected in a closed container? 2. Would the container become heavier when it is added? 3. Does it take up space that something else cannot share at the same time? 4. If all three are yes, it is matter; if not, it is probably a form of energy or an idea.

Visual explanation

Picture a sealed glass box on a sensitive balance. Pump in air: the reading rises. Now shine a torch into the box, play music next to it and warm it with a hair dryer: the reading does not change (once the box has settled). Only the air changed the mass. A simple diagram can show "matter" arrows (air entering) and "energy" arrows (light, sound, heat) crossing the box walls.

Real-world analogy

Think of a delivery van (matter) and the music playing on its radio (energy). You could weigh the van and measure how much space it fills. The music fills the cab and travels to your ears, but it has no weight and takes up no parking space. Matter is the van; energy is what it carries or gives off.

Real-world example

A solar panel on a roof is matter — silicon, glass, aluminium and plastic. The sunlight falling on it is energy. The panel converts some of that light energy into electrical energy, but the panel does not gain mass as it works. Engineers design panels by choosing materials (matter) that absorb light (energy) efficiently.

Why?

Why does sound need matter while light does not? Sound is a chain of pushes: each particle nudges the next. Without particles, there is nothing to push, so sound cannot cross a vacuum. Light is a wave of electric and magnetic fields that sustains itself, so it can travel through completely empty space.

Common misconception

A common mistake is to say that fire or a flame is "made of heat". A flame is actually hot gases — including carbon dioxide, water vapour and glowing specks of soot — which are matter. The heat and light the flame gives off are energy. So a flame contains matter, and it releases energy.

Worked example

Question: Classify each as matter or not matter, giving a reason: (a) smoke, (b) a shadow, (c) an echo.

Reasoning: Smoke contains tiny solid particles and gases, so it has mass and takes up space. A shadow is simply a region where light is blocked; nothing is there. An echo is reflected sound, which is energy.

Answer: (a) matter, (b) not matter, (c) not matter.

Quick check

1. Why can sound not travel through outer space? Answer: Sound is carried by vibrating particles, and space is almost empty of particles, so there is nothing to carry the vibration.

Exam focus

Questions often list a mixture of materials and energy forms. Credit is given for explaining your choice using the definition (mass and volume) rather than for the answer alone. Avoid saying energy is "weightless matter" — energy is not matter at all.

Advanced insight

Although light has no mass at rest, it carries momentum and can push on objects. Solar sails on some spacecraft use the tiny pressure of sunlight to accelerate. This does not make light matter; it shows that energy and momentum can be transferred without particles of matter.

Summary

Matter has mass and takes up space; energy does not. Light, heat, sound, electricity, shadows and ideas are not matter. Sound needs matter to travel through, whereas light can cross empty space. Chemical changes always involve both matter being rearranged and energy being transferred, so chemists must describe both.

Practice questions

1. Which of these is matter: steam, sunlight, a song, a raindrop? Answer: Steam and a raindrop are matter; sunlight and a song are energy. 2. A student says "heat is a substance that flows into hot objects". Correct the statement. Answer: Heat is not a substance; it is energy transferred from a hotter object to a cooler one, and heating does not change an object's mass. 3. Explain why a candle flame contains matter but its light does not. Answer: The flame is made of hot gases and glowing soot particles, which have mass and volume; the light it gives off is energy. 4. Give one piece of evidence that sound needs matter to travel. Answer: When air is pumped out of a jar containing a ringing bell, the sound fades even though the bell can still be seen ringing.