MATTER AND MEASUREMENT
The Study of Chemistry
• is the study of properties of materials and changes that they undergo.
• can be applied to all aspects of life.
The Atomic and Molecular Perspective of Chemistry
Chemistry involves the study of the properties and the behavior of matter.
• is the physical material of the universe.
• has mass.
• occupies space.
Examples of matter:
~100 elements constitute all matter.
A property is any characteristic that allows us to recognize a particular type of matter and to distinguish it from other types of matter.
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Gas (vapor)-No fixed volume or shape, conforms to shape of container compressible.
Liquid-Fixed volume, no fixed shape, incompressible.
Solid-fixed volume and shape, rigid, incompressible.
Why these differences between gas, liquid and solid?
We must look at the properties on a molecular level:
Gas: Molecules far apart moving rapidly collide often.
Liquid: Molecules closer than gas, move rapidly can slide over each other.
Solid: Molecules packed closely in definite arrangements.
Matter that has distinct properties and composition that doe not vary from sample to sample.
• Elements-cannot be decomposed into other substances.
• Compounds-composed of two or more elements.
• There are 116 elements.
• They vary in abundance.
• Each is given a unique name and is abbreviated by a chemical symbol.
• They are organized in the periodic table.
• Each is given a one- or two – letter symbol derived from its name.
Common elements are found in Table 1.2 LEARN!!!!
Compounds are combinations of elements.
Elements react with each other to form compounds. (properties different from constituent elements.
Water is a combination of the elements hydrogen and oxygen.
1) H2(g) +½O2(g) → H2O(l)
H2O: 89% O2 and 11% H2
2) Fe(s) + 3/2 O2(g) Fe2O3(s)
Fe2O3: 69.9% Fe and 30.1% O
Law of Constant Composition (Law of Definite Proportions)-the elemental composition of a pure compound is always the same.
i.e. Water is always 89% O2 and 11% H2.
Mixture-a combination of two or more substances in which each substance retains its own chemical identity.
• Each substance retains its own identity; each substance is a component of the mixture
Components of Mixtures
*Solvent-present in greater quantity
*Solute-present in lesser quantity
• Mixtures have variable composition.
Heterogeneous Mixtures-do not have the same composition, properties and appearance.
Homogeneous Mixtures- are uniform throughout, e.g. , air, sweet tea; they are called solutions. Solutions can be gas, liquid or solid.
Properties of Matter
Every substance has a unique set of properties that allow us to distinguish it from other substances.
Properties can be classified as:
Physical Properties-can be measured without changing the identity and composition of the substance.
Chemical Properties-describe the way a substance may change or react to form other substances.
Intensive Properties-do not depend on the amount of the sample being examined.
Extensive Properties:-depend on the quantity of substance present.
“Intensive properties give an idea of the composition of a substance whereas extensive properties give an indication of the quantity of a...