MATTER & MASS • Matter is anything that has mass and occupies space. • Mass is a measurement of the amount of matter in an object. • Mass is independent of the location of an object. • An object on the earth has the same mass as the same object on the moon.
WEIGHT • Weight is a measurement of the gravitational force acting on an object. • Weight depends on the location of an object. • An object weighing 1.0 lb on earth weighs about 0.17 lb on the moon.
PHYSICAL & CHEMICAL PROPERTIES • PHYSICAL PROPERTIESOF MATTER • Physical properties can be observed or measured without attempting to change the composition of the matter being observed. • Examples: color, shape and mass • CHEMICAL PROPERTIESOF MATTER • Chemical properties can be observed or measured only by attempting to change the matter into new substances. • Examples: flammability and the ability to react (e.g. when vinegar and baking soda are mixed)
PHYSICAL & CHEMICAL CHANGES • PHYSICAL CHANGES OF MATTER • Physical changes take place without a change in composition. • Examples: freezing, melting, or evaporation of a substance (e.g. water) • CHEMICAL CHANGES OF MATTER • Chemical changes are always accompanied by a change in composition. • Examples: burning of paper and the fizzing of a mixture of vinegar and baking soda
PARTICULATE MODEL OF MATTER • All matter is made up of tiny particles called molecules andatoms. • MOLECULES • A molecule is the smallest particle of a pure substance that is capable of a stable independent existence. • ATOMS • Atoms are the particles that make up molecules.
MOLECULE CLASSIFICATION • Diatomic molecules contain two atoms. • Triatomic molecules contain three atoms. • Polyatomic molecules contain more than three atoms.
MOLECULE CLASSIFICATION (continued) • HOMOATOMIC MOLECULES • The atoms contained inhomoatomic moleculesare of the same kind. • HETEROATOMIC MOLECULES • The atoms contained inheteroatomic moleculesare of two or more kinds. homoatomic heteroatomic
MOLECULE CLASSIFICATION EXAMPLE • Classify the molecules in these diagrams using the terms diatomic, triatomic, or polyatomic molecules. • Solution: H2O2 is a polyatomic molecule, H2O is a triatomic molecule, and O2 is a diatomic molecule. • Classify the molecules using the terms homoatomic or heteroatomic molecules. • Solution: H2O2 and H2O are heteroatomic molecules and O2 is a homoatomic molecule.
CLASSIFICATION OFMATTER • Matter can be classified into several categories based on chemical and physical properties. • PURE SUBSTANCES • Pure substances have a constant composition and a fixed set of otherphysicaland chemical properties. • Example: pure water (always contains the same proportions of hydrogen and oxygen and freezes at a specific temperature)
CLASSIFICATION OF MATTER(continued) • MIXTURES • Mixturescan vary in composition and properties. • Example: mixture of table sugar and water (can have different proportions of sugar and water) • A glass of water could contain one, two, three, etc. spoons of sugar. • Properties such as sweetness would be different for the mixtures with different proportions.
HETEROGENEOUS MIXTURES • The properties of a sample of a heterogeneous mixture depends on the location from which the sample was taken. • A pizza pie is a heterogeneous mixture. A piece of crust has different properties than a piece of pepperoni taken from the same pie.
HOMOGENEOUS MIXTURES • Homogeneous mixtures are also called solutions. The properties of a sample of a homogeneous mixture are the same regardless of where the sample was obtained from the mixture. • Samples taken from any part of a mixture made up of one spoon of sugar mixed with a glass of water will have the same properties, such as the same taste.
ELEMENTS • Elementsare pure substances that are made up of homoatomic molecules or individual atoms of the same kind. • Examples: oxygen gas made up of homoatomic molecules and copper metal made up of individual copper atoms
COMPOUNDS • Compoundsare pure substances that are made up of heteroatomic molecules or individual atoms (ions) of two or more different kinds. • Examples: pure water made up of heteroatomic molecules and table salt made up of sodium atoms (ions) and chlorine atoms (ions)
MATTER CLASSIFICATION SUMMARY
MATTER CLASSIFICATION EXAMPLE • Classify H2, F2, and HF using the classification scheme from the previous slide. • Solution: • H2, F2, and HF are all pure substances because they have a constant composition and a fixed set of physicaland chemical properties. • H2 and F2 are elements because they are pure substances composed of homoatomic molecules. • HF is a compound because it is a pure substance composed of heteroatomic molecules.
MEASUREMENTS & UNITS • Measurements consist of two parts, a number and a unit or label such as feet, pounds, or gallons. • Measurement units are agreed upon by those making and using the measurements. • Measurements are made using measuring devices (e.g. rulers, balances, graduated cylinders, etc.).
METRIC SYSTEM • The metric system is a decimal system in which larger and smaller units are related by factors of 10. • TYPES OF METRIC SYSTEM UNITS • Basic or defined units [e.g. 1 meter (1 m)] are used to calculate derived units [e.g. 1 square meter (1 m2)].
THE USE OF PREFIXES • Prefixes are used to relate basic and derived units. • The common prefixes are given in the following table:
TEMPERATURE SCALES • The three most commonly-used temperature scales are the Fahrenheit, Celsius and Kelvin scales. • The Celsius and Kelvin scales are used in scientific work.
TEMPERATURE CONVERSIONS • Readings on one temperature scale can be converted to the other scales by using mathematical equations. • Converting Fahrenheit to Celsius. • Converting Celsius to Fahrenheit. • Converting Kelvin to Celsius. • Converting Celsius to Kelvin.
TEMPERATURE CONVERSION PRACTICE • Covert 22°C and 54°C to Fahrenheit and Kelvin.
COMMONLY USED METRIC UNITS
SCIENTIFIC NOTATION • Scientific notation provides a convenient way to express very large or very small numbers. • Numbers written in scientific notation consist of a product of two parts in the form M x 10n, where M is a number between 1 and 10 (but not equal to 10) and n is a positive or negative whole number. • The number M is written with the decimal in the standard position.
SCIENTIFIC NOTATION (continued) • STANDARD DECIMAL POSITION • The standard position for a decimal is to the right of the first nonzero digit in the number M. • SIGNIFICANCE OF THE EXPONENT n • A positive n value indicates the number of places to the right of the standard position that the original decimal position is located. • A negative n value indicates the number of places to the left of the standard position that the original decimal position is located.
SCIENTIFIC NOTATION MULTIPLICATION • Multiply the M values (a and b) of each number to give a product represented by M'. • Add together the n values (y and z) of each number to give a sum represented by n'. • Write the final product as M' x 10n'. • Move decimal in M' to the standard position and adjust n' as necessary.
SCIENTIFIC NOTATION DIVISION • Divide the M values (a and b) of each number to give a quotient represented by M'. • Subtract the denominator (bottom) n value (z) from the numerator (top) n value (y) to give a difference represented by n'. • Write the final quotient as M' x 10n'. • Move decimal in M' to the standard position and adjust n' as necessary.
