Chemistry Chapter 1

Physical Means of Separation

• Physical means can be used to separate a mixture into its pure components
• Examples of physical means include distillation and magnets

Elements

• An element is a substance that cannot be separated into simpler substances by chemical means
• 114 elements have been identified, with 82 occurring naturally on Earth and 32 created by scientists
• Examples of elements include gold, aluminum, lead, oxygen, and carbon

Compounds

• A compound is a substance composed of atoms of two or more elements chemically united in fixed proportions
• Compounds can only be separated into their pure components (elements) by chemical means
• Examples of compounds include water (H2O), glucose (C6H12O6), and ammonia (NH3)

The Three States of Matter

• The three states of matter are solid, liquid, and gas
• Physical state properties of the three states of matter:
  • Solid: fixed volume and shape, particles are closely packed and have low kinetic energy
  • Liquid: fixed volume, takes shape of container, particles are close together and have moderate kinetic energy
  • Gas: variable volume, takes volume of container, particles are far apart and have high kinetic energy

Physical and Chemical Changes

• A physical change does not alter the composition or identity of a substance
• A chemical change alters the composition or identity of the substance(s) involved

Extensive and Intensive Properties

• An extensive property of a material depends on how much matter is being considered
• Examples of extensive properties include mass, length, and volume
• An intensive property of a material does not depend on how much matter is being considered
• Examples of intensive properties include density, temperature, and color

Matter

• Matter is anything that occupies space and has mass
• The SI unit of mass is the kilogram (kg)
• Weight is the force that gravity exerts on an object

International System of Units (SI)

• The SI derived unit for volume is the cubic meter (m3)
• 1 cm3 = (1 x 10-2 m)3 = 1 x 10-6 m3
• 1 dm3 = (1 x 10-1 m)3 = 1 x 10-3 m3
• 1 L = 1000 mL = 1000 cm3 = 1 dm3

Density

• The SI derived unit for density is kg/m3
• Density formula: mass density = volume (m d= V)
• Example problem: A piece of platinum metal with a density of 21.5 g/cm3 has a volume of 4.49 cm3. What is its mass?

Chemistry: A Science for the 21st Century

• Chemistry is the study of matter and the changes it undergoes
• Chemistry is important in various fields, including health and medicine, materials and technology, food and agriculture, and energy and the environment

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