8.1 Matter
Matter consists of tiny and discrete particles which exist as atoms, molecules, or ions. Based on the types of particles they contain, substances can be classified into atomic substances, molecular substances, and ionic substances.
Learning Objectives
- State that matter is made of three types of particles: atoms, molecules, and ions.
- Define and differentiate between atomic substances, molecular substances, and ionic substances.
- Describe the particle arrangements and compositions of atomic, molecular, and ionic substances.
- Explain with examples how a single element can exist in different forms (atoms, molecules, or ions) in various substances.
Types of Substances and Particle Arrangements
Compare the microscopic views of atomic, molecular, and ionic substances with their real-world examples.
Short Explanation
What is matter made of?
Matter consists of tiny and discrete particles. It is formed by three types of particles: atoms, molecules, and ions.
Particles of Matter
Atom
The smallest particle of an element and the most basic unit in an element. It consists of subatomic particles: protons, neutrons, and electrons.
Molecule
Consists of two or more atoms that are chemically combined. Molecules can be a combination of the same type or different types of atoms.
Ion
A charged particle, either positively charged or negatively charged. An ion is formed when an atom loses or gains electrons.
Classification of Substances Based on Particles
| Type of substance | Particles present | Examples |
|---|---|---|
| Atomic substance | Only atoms | All metals (e.g., gold metal) and inert gases (e.g., helium in balloons) |
| Molecular substance | Molecules made up of two or more atoms combined chemically | Oxygen gas, \(\text{O}_2\), in oxygen tanks; water, \(\text{H}_2\text{O}\), in sea water |
| Ionic substance | Positive ions (cations) and negative ions (anions) arranged together | Sodium chloride (common salt) |
Existence of Elements in Various Forms
An element can exist in different particle forms (atoms, molecules, or ions) depending on the substance.
Iron (Element)
Exists in the form of atoms in the head of a hammer (pure metal). Exists in the form of ions in rust.
Hydrogen (Element)
Exists in the form of molecules in the air (hydrogen gas, \(\text{H}_2\)). Exists in the form of ions in lime juice (acidic solution).
Try to Answer First
Answer in your mind, then press “Check Answer”.
What type of particle is formed when an atom gains or loses electrons?
In what form does iron exist in rust?
What is the difference between the arrangement of atoms in metals compared to inert gases?
Common Mistakes
- Confusing molecules with compounds: assuming molecules can only be formed by different elements. In fact, molecules can consist of identical atoms, such as oxygen gas, \(\text{O}_2\).
- Assuming an element can only exist in one form: overlooking that an element like iron or hydrogen can exist as atoms, molecules, or ions depending on the substance.
Concept Misunderstandings
Inert gases are molecular substances because they are gases.
Inert gases are atomic substances because they exist as single, separate atoms spread far apart.
Ionic substances are made up of non-metals only.
Ionic substances are formed by the reaction between metal elements and non-metal elements.
Summary
- Matter is composed of atoms, molecules, or ions.
- Atomic substances: Contain only atoms (all metals and inert gases).
- Molecular substances: Contain two or more atoms chemically combined (most non-metals and non-metal compounds).
- Ionic substances: Formed from reactions between metals and non-metals, containing positive and negative ions.
- The same element can exist in different forms in daily substances (e.g., iron exists as atoms in a hammer and ions in rust).
Short Activity
A. Objective Quiz
1 Which of the following substances is an atomic substance?
2 How are ionic substances formed according to the textbook?
B. Fill in the Blanks
3 An ion is formed when an atom loses or gains .
4 In lime juice, the element hydrogen exists in the form of .
C. Drag and Drop: Match the Substance to Its Particle Type
Drag each substance to the correct type of particles it is made up of. On a phone, tap an answer first, then tap a matching box. Tap the Answer Choices area to return a selected item.
C. Match the Substance to Its Particle Type
Write the correct particle type next to each substance.
| Substance | Particle Type |
|---|---|
| 1. Gold metal | |
| 2. Oxygen gas | |
| 3. Common salt | |
| 4. Helium gas |
Answer choices: Atoms arranged in a neat and orderly manner • Molecules made of two chemically combined atoms of the same type • Positive ions and negative ions combined • Atoms spread far apart with no regular arrangement
