CHEMISTRY: TYPES OF MATTER

Types of Matter

Around the world 2 categories of matter can be distinguished.

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Homogeneous: Material that has a uniform composition throughout.

• Homogeneous matter can contain more than one type of particle, but particles are uniformly distributed.
  • E.g. Sugar dissolved in water is a matter that contains both sugar and water but is homogeneous because the smallest particles that make up sugar and water are uniformly distributed.

Heterogeneous: Material that has varying compositions.

• Heterogeneous materials are made up of parts with different  chemical and physical properties. These parts are not uniformly mixed or dispersed.
  • E.g. A chocolate chip cookie has pieces of chocolate embedded in the cookie dough.

Matter can be divided into the major categories of pure substances and mixtures. Pure substances or homogeneous; mixtures can be either heterogeneous or homogeneous.

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Pure substances

• A sample of matter is pure substance if its composition is the same throughout the sample.

• Pure substances have constant composition throughout a sample and from one sample to another.

• The two types of pure substances are elements and compounds. Oxygen gas(element) and water(compound) are examples of pure substances.

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Elements

• Elements are substances that cannot be broken down or decomposed into simpler substances by chemical means.

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Compounds

• Compounds are composed of two or more elements that are chemically combined in definite proportions by Mass.
• Substances in compounds do not retain their properties, the compound has its own properties.
• Although all compounds contain at least two different types of atoms, the composition of a compound is the same throughout.

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Mixtures: combinations of two or more pure substances that can be separated by physical means.

• Mixtures are different from compounds because their composition is not definite/fixed and parts can be physically separated.
  • E.g. When sugar is dissolved in water, it doesn't disappear. If the water evaporates, the sugar is Left Behind; the water and sugar separate.
• Substances in mixtures retain their properties
• There are homogeneous and heterogeneous mixtures.

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