Page 347 - General Knowledge

GENERAL KNOWLEDGE 2019

GENERAL SCIENCE : CHEMISTRY

1. MATTER

 The definition of matter is, anything that has mass and occupies space.
 Volume is the unit used to measure the amount of space an object occupies.
 You can think of the volume unit in terms of how big something is, like a hot air balloon
occupies a lot of space.
 The other half of the definition deals with the term mass.
 Mass is a measure of the amount of matter.
 This differs from the size of the matter, the volume.
 The unit of mass is gram.
 Mass differs from weight, even though we, incorrectly use them interchangeably.

Pure substances and mixtures

Matter is divided into two broad categories.
Pure substances

 It has fixed properties
 It is composed of constant composition.
 It cannot be broken apart physically.
Mixtures
 Mixtures are properties vary with composition.
 It has proportions of the components varying throughout mixture.

 It can be physically separated into two or more pure substances.
Elements and Compounds
Pure substances are divided into two categories

Elements
 It is composed of one type of atom.
 It cannot be broken apart chemically.

Compounds
 It is composed of more than one type of atom chemically bonded, called a molecule.
 It can be broken apart chemically, sometimes this is very difficult to do, sometimes not.
 It has pieces that are either individual atoms or smaller molecules
 It cannot be broken by physical means.
 You cannot hit the molecule and break the bonds or pull them apart or filter them apart.

Heterogeneous and Homogeneous
mixtures
 Mixtures can be separated by physical means like filtration or evaporation.
 Mixtures are divided into two categories.
 Heterogeneous properties are not the same throughout the mixture.
 Homogeneous properties are the same throughout the mixture.
Elements
 Element: A pure substance composed of only one type of atom.

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