What is Matter? Mass, Volume & Weight: Fifth Grade Science
Everything you can touch, taste, breathe, and stand upon is made of matter, the fundamental physical substance that occupies space and possesses mass throughout the universe.
The Definition of Matter
In physical science, matter is defined as anything that has mass and takes up space (volume). The computer or tablet you are reading this on, the water inside your cells, the nitrogen and oxygen gases in the atmosphere, and the dirt beneath your shoes are all forms of matter. Things that are not matter include forms of energy and abstract concepts, such as light, heat, sound, radio waves, gravity, thoughts, and memories, which do not have physical mass or displace volume.
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| MATTER VERSUS NON-MATTER |
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| Matter (Has Mass and Volume) | Non-Matter (Pure Energy or Concept) |
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| Air inside a balloon | Sunlight streaming through a window |
| Liquid water in an ocean | Sound waves from a violin string |
| Solid iron nail | Heat radiating from a camp stove |
| Microscopic bacteria and viruses | Magnetic attraction force |
| Dust grains floating in sunlight | Thoughts and emotional feelings |
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The Particulate Nature of Matter
Even though a gold ring or a cup of clear water looks smooth and continuous to our eyes, all matter is composed of tiny, discrete particles that are constantly in motion. These particles—atoms and molecules—are so tiny that a single drop of water contains more than a sextillion (a 1 followed by 21 zeros) water molecules.
Proving that Invisible Air is Matter
Because air is invisible, people sometimes wonder whether it truly qualifies as matter. You can easily prove air is matter through two physical tests:
- Testing for mass: If you place an uninflated rubber balloon on a precision digital balance, record its mass, inflate it fully with room air, and reweigh it, the inflated balloon will have a higher mass because of the air trapped inside.
- Testing for volume: If you invert a dry drinking glass with a crumpled paper towel wedged inside its bottom and push it straight down into a bucket of water, the paper towel stays completely dry because the volume of air trapped in the glass prevents water from entering.
Mass, Volume, and Weight Compared
To describe and quantify matter with scientific precision, researchers examine three related but distinct physical properties: mass, volume, and weight.
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| MASS, VOLUME, AND WEIGHT COMPARISON |
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| Property | Definition | Standard Metric Unit |
+-----------------------+-----------------------+--------------------------+
| Mass | Amount of matter in | Gram (g), Kilogram (kg) |
| | an object | |
| Volume | Amount of 3D space an | Milliliter (mL), Liter |
| | object occupies | (L), Cubic cm (cm³) |
| Weight | Gravitational force | Newton (N) |
| | pulling on mass | |
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Measuring Solid Volume
Volume can be measured in two different ways depending on whether the solid has a regular geometric shape or an irregular shape:
- Regular geometric solids (like a rectangular wooden block): Measure length, width, and height with a metric ruler, and multiply them together: Volume = Length x Width x Height. For example, a block 4 cm long, 3 cm wide, and 2 cm tall has a volume of 24 cubic centimeters (cm³).
- Irregular solids (like a jagged pebble or mineral sample): Use the water displacement method with a graduated cylinder. First, record the initial volume of water. Next, carefully slide the pebble in. Then record the final water volume. The volume of the irregular solid equals the final volume minus the initial volume (V_solid = V_final - V_initial). Because 1 milliliter of water equals exactly 1 cubic centimeter (1 mL = 1 cm³), liquid displacement yields direct solid volume.
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| WATER DISPLACEMENT METHOD |
| |
| Initial Volume: 50 mL Final Volume with Stone: 68 mL |
| | | | | |
| 70 |-- --| 70 |--~~~~| <-- Water rose |
| 60 |-- --| 60 |--~~~~| |
| 50 |--~~~~| <-- Water level 50 |--~~~~| |
| 40 |--~~~~| 40 |--~~~~| |
| 30 |--~~~~| 30 |--[O]-| <-- Submerged stone|
| +------+ +------+ |
| |
| Volume of Stone = 68 mL - 50 mL = 18 mL = 18 cm³ |
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The Difference Between Mass and Weight
Mass is an intrinsic property that depends solely on how many atoms are packed inside an object. Weight is the extrinsic measurement of how strongly gravity pulls downward on that mass. A 60-kilogram person has a mass of 60 kg whether standing on Earth, floating weightless in orbit inside the International Space Station, or walking on the Moon. However, that person would weigh roughly 588 Newtons on Earth, 98 Newtons on the Moon, and zero Newtons while free-floating in deep space.
Exercises and Solutions
Exercise 1: Calculating Solid Volume by Displacement. A student wants to find the volume of a brass bolt. The student pours water into a graduated cylinder up to the 42.0 mL mark. After lowering the brass bolt into the cylinder so that it is completely submerged, the water level rises to the 56.5 mL mark. Calculate the volume of the brass bolt in milliliters and in cubic centimeters.
Solution 1: The volume of the bolt is calculated by subtracting the initial water volume from the final submerged water volume. Volume = 56.5 mL - 42.0 mL = 14.5 mL. Because one milliliter of liquid volume is equivalent to one cubic centimeter of solid volume (1 mL = 1 cm³), the volume of the brass bolt is exactly 14.5 cubic centimeters.
Exercise 2: Classifying Phenomena as Matter or Non-Matter. A student sets up an electric lamp that illuminates a potted plant. Analyze the following five items and classify each as matter or non-matter, giving a scientific justification for each: the ceramic pot, the light rays shining on the leaves, the potting soil, the warmth radiating from the bulb, and the oxygen gas released by the plant.
Solution 2: The ceramic pot, the potting soil, and the oxygen gas are all classified as matter because each consists of physical atoms that have measurable mass and take up 3D volume in space. The light rays shining on the leaves and the warmth (thermal radiation) radiating from the bulb are classified as non-matter because they are forms of pure electromagnetic energy that do not have mass and do not occupy physical volume.