Back to GENERAL SCIENCE
Unit 1•Lesson 6 2 min read

Material Science: Properties of Matter

6/18

Learning Objectives

Distinguish between physical and chemical properties of matter.
Define density and calculate it using the formula ρ = m/V.
Describe the states of matter (solid, liquid, gas, plasma) in terms of particle arrangement and energy.
Define elasticity, plasticity, and hardness.

The Stuff of the Universe: Matter and Its Properties

Material science is an interdisciplinary field that studies the properties of matter and their applications.

Physical vs. Chemical Properties

A physical property is a characteristic that can be observed or measured without changing the chemical identity of the substance. Examples: color, density, melting point, boiling point, hardness.
A chemical property describes a substance's ability to undergo a specific chemical change. Examples: flammability, corrosiveness, reactivity with acid.

Density

Density (ρ, rho) is a fundamental physical property defined as the mass of a substance per unit volume.

Formula: ρ = m / V
It is an intensive property, meaning it does not depend on the amount of the substance. A small iron nail and a large iron girder have the same density.
The SI unit for density is kilograms per cubic meter (kg/m³), but grams per cubic centimeter (g/cm³) or grams per milliliter (g/mL) are also common.

States of Matter

Solid: Particles are tightly packed in a fixed arrangement and have low kinetic energy. Solids have a definite shape and a definite volume.
Liquid: Particles are close together but can move past one another. They have more kinetic energy than solids. Liquids have a definite volume but an indefinite shape (they take the shape of their container).
Gas: Particles are far apart and move randomly and rapidly. They have high kinetic energy. Gases have an indefinite shape and an indefinite volume (they expand to fill their container).
Plasma: A state of matter similar to a gas in which a certain portion of the particles are ionized. It is the most abundant state of matter in the universe (found in stars).

Mechanical Properties

Hardness: A material's resistance to localized plastic deformation such as scratching or indentation.
Elasticity: The ability of a material to deform under stress (like being stretched or compressed) and then return to its original shape when the stress is removed.
Plasticity: The ability of a material to undergo permanent deformation (a non-reversible change of shape) in response to applied forces. If you bend a paperclip, it has undergone plastic deformation.

Key Terms

Density
The degree of compactness of a substance, defined as its mass per unit volume (ρ = m/V).
Physical Property
A characteristic of a substance that can be observed or measured without changing the identity of the substance.
Chemical Property
A property or characteristic of a substance that is observed during a reaction in which the chemical composition or identity of the substance is changed.
Elasticity
The ability of an object or material to resume its normal shape after being stretched or compressed.
Plasma
An ionized gas consisting of positive ions and free electrons in proportions resulting in more or less no overall electric charge, typically at very high temperatures.

Check Your Understanding

1

The flammability of gasoline is an example of what kind of property?

2

An object has a mass of 150 grams and a volume of 50 cm³. What is its density?

3

What is the most abundant state of matter in the universe?

Previous
Environmental Science: Ecosystems and Biomes
Next
Logic and Reasoning: Induction vs. Deduction