Chemistry Fundamentals

Chemistry: Elements, Compounds, and Mixtures

• In chemistry, pure substances can consist of a single element or compound with no other substances added.

• A beaker of pure water contains only H2O molecules and nothing else.

• When salt is added to the water, a mixture is produced, as it contains two or more elements or compounds physically mixed together.

• Mixtures do not involve chemical combinations, and the chemical properties of the substances in a mixture remain unchanged.

• Substances in mixtures can be separated by physical means.

• Air is an example of a mixture, consisting of nitrogen, oxygen, and other gases like carbon dioxide and argon.

• Before 1669, elements such as carbon, sulfur, iron, copper, arsenic, silver, tin, antimony, gold, and mercury were discovered.

• The concept of an atom being indivisible is essential in understanding elements, compounds, and mixtures.

• Visual representations can help in understanding these concepts.

• The term "pure" has different meanings in everyday language and in chemistry.

• Pure substances may consist of a single element or compound with no other substances added.

• Mixtures consist of two or more elements or compounds physically mixed together, without chemical combination.

• Air is an example of a mixture, containing nitrogen, oxygen, and other gases.

• Before 1669, several elements were discovered, including carbon, sulfur, iron, copper, arsenic, silver, tin, antimony, gold, and mercury.