6 Questions
What is a substance?
A material or mixture of materials with a specific chemical composition and properties
What is an example of an element?
Hydrogen
What is a physical property of a substance?
Color
What is the state of matter where particles are widely spaced and can move freely?
Gas
What is an example of a physical change?
Melting
Why are substances important?
They make up everything around us and are crucial in various fields
Study Notes
Definition and Classification
- A substance is a material or a mixture of materials that has a specific chemical composition and properties.
- Substances can be classified into:
- Elements: substances that consist of only one type of atom (e.g. hydrogen, oxygen)
- Compounds: substances that consist of two or more different elements (e.g. water, salt)
- Mixtures: substances that consist of two or more different substances, but not in a fixed ratio (e.g. air, soil)
Properties of Substances
- Physical properties:
- Color
- Odor
- Texture
- Melting and boiling points
- Solubility
- Chemical properties:
- Reactivity
- Flammability
- pH level
- Reactivity with other substances
States of Substances
- Solid: particles are closely packed and have a fixed shape
- Liquid: particles are close together but can move freely
- Gas: particles are widely spaced and can move freely
- Plasma: high-energy state of matter, where atoms are ionized
Changes of Substances
- Physical changes:
- Changes in state (e.g. melting, freezing)
- Changes in shape or form
- Chemical changes:
- Changes in chemical composition (e.g. burning, rusting)
- Formation of new substances
Importance of Substances
- Substances are the building blocks of matter and make up everything around us
- Understanding substances is crucial in various fields, such as:
- Chemistry
- Biology
- Physics
- Engineering
- Medicine
Definition and Classification
- A substance is a material or mixture with a specific chemical composition and properties.
- Substances can be classified into three main categories: elements, compounds, and mixtures.
- Elements consist of only one type of atom (e.g. hydrogen, oxygen).
- Compounds consist of two or more different elements (e.g. water, salt).
- Mixtures consist of two or more different substances, but not in a fixed ratio (e.g. air, soil).
Properties of Substances
Physical Properties
- Color
- Odor
- Texture
- Melting and boiling points
- Solubility
Chemical Properties
- Reactivity
- Flammability
- pH level
- Reactivity with other substances
States of Substances
- Solid: particles are closely packed and have a fixed shape.
- Liquid: particles are close together but can move freely.
- Gas: particles are widely spaced and can move freely.
- Plasma: high-energy state of matter, where atoms are ionized.
Changes of Substances
Physical Changes
- Changes in state (e.g. melting, freezing).
- Changes in shape or form.
Chemical Changes
- Changes in chemical composition (e.g. burning, rusting).
- Formation of new substances.
Importance of Substances
- Substances are the building blocks of matter and make up everything around us.
- Understanding substances is crucial in various fields, such as chemistry, biology, physics, engineering, and medicine.
Learn about the definition and classification of substances in chemistry, including elements, compounds, and mixtures. Understand the properties of substances and how they differ from one another.
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