Chapter 1 Matter and Measurement Honors Chemistry Chapter 1 Matter and Measurement

1.1 The Study of Chemistry Chemistry: The study of matter and the changes it undergoes Matter anything that has mass and occupies space ( has volume) Atoms: the building blocks of matter Elements: pure substances that contain identical atoms Molecules: combinations of atoms

1.1 Why study Chemistry? Chemistry is called the central science because it overlaps all the other sciences Chemistry tells us how and why our world works

1.2 Classifications of Matter Two ways that matter is usually classified Physical state Solid, liquid, gas, plasma Composition Element, compound, mixture A pure substance is matter that has a fixed composition and distinct properties

1.2 Classifications Of Matter Pure Substances can be classified as either elements or compounds Elements are pure substances that cannot be broken down into simpler substances Compounds: combinations of two or more elements, can be broken down chemically to the base elements

1.2 Classifications of Matter Mixtures are combination of two or more substances that are not chemically combined, can be separated by physical means, and it substance retains it chemical identity and properties Heterogeneous Mixtures: non-uniform Homogeneous Mixtures: uniform and consistent Solutions are Homogeneous Mixtures

1.2 Classification of Matter We can separate a mixture by taking advantage of the physical properties of the components in the mixture Elements There are 112 known elements Listed in periodic table using chemical symbols

1.2 Classification of Matter Compounds are combinations of elements Always for in whole number ratios of elements Law Of Constant Composition: compounds are formed by the whole number ratio combination of elements, the formulas for these compounds are always the same

1.3 Properties of Matter Physical Properties: can be observed or measured without changing the chemical composition of the substance Chemical Properties: how substances react to other substances, to observe, the chemical composition usually changes E.g. flammability

1.3 Properties of Matter Physical Change: a change in appearance, no change in the chemical composition Change in state Chemical Changes: a substance is changed into a new substance with different chemical properties

1.3 Properties of Matter The Scientific method: organized way to solve problems Steps 1. Define a problem 2. Form hypothesis 3. Experiment, collect data 4. Theorize 5. Publish Results

1.4 Units of Measurement Quantitative: related to numbers Qualitative: descriptions, attributes The units of acceptable measurements in all science is the metric system Consistent Measurement allows scientists to communicate their results “SI” system of Measurement

1.4 Units of Measurement 7 Base Units in SI 1. Length…………meter 2. Mass…………..kilogram 3. Time…………..second 4. Quantity……….mole 5. Temperature…..Kelvin 6. Electric Current….ampere 7. Luminous Intensity….candela

1.4 Units of Measurement Derived units are combinations of base units Volume, density, force, pressure

1.5 Uncertainty in Measurement Numbers are exact or inexact All measurements contain some error 1. The instrument 2. Usually involve estimation Precision: How well a piece of equipment makes a consistent measurement Accuracy: how close the measurement is to an accepted value

1.5 Uncertainty In Measurement Significant Figures all numbers known in a measurement that are exact plus one estimated digit that is inexact (estimate) Rules: 1. Nonzero digits are always significant 2. Zeros between nonzero digits are always significant 3. Zeros at the beginning of numbers are never significant 4. Zeros at the end of a number to the right of a decimal are significant 5. Zeros at the end of a number with no decimal are not significant

1.5 Uncertainty in Measurement Significant Figure Calculations Addition and Subtraction: the result can not have more digits to the right of the decimal than any of the original numbers Multiplication and Division: the result must be reported with the same number of significant figures as the the measurement with the fewest significant figures The weakest link

1.6 Dimensional Analysis Units are treated as algebraic quantities Solve for the units, if it gives the correct units in the answer, the problem will most likely be correct Conversion factors are used to change a number from one system of measurement to another Numbers without units are worthless