Chapter 1 Introduction: Matter and Measurement Chapter 1: Matter and Measurement Matter Classification of Matter Properties Measurement Units (SI, metric) Significant Figures Unit Conversions Classification of Matter Pure Substances Elements Compounds Molecules Mixtures Homogeneous Heterogeneous Elements Elements are composed of atoms of only one type of element. Examples: Iron metal (Fe) Sulfur (S or S8) Oxygen (O2) Bromine (Br2) Elements Know the element names and symbols elements, particularly the main group elements. Groups of : Li, Be, B, C, N, O, F, Ne Compounds Compounds are combinations of atoms of more than one type of element. Examples: GaAs (gallium arsenide) Methane (CH4) Water (H2O) Ammonia (NH3) Molecules Molecules are groups of atoms bonded chemically. Molecules can be elements or compounds H2 CO2 O2 CH3CH2OH Elements and Compounds Molecules Molecules can be Elements or Compounds Classification of Matter SiO2, Al2O3, K2O, FeO, Fe2O3, MgO, etc. Mixtures 2 or more pure substances that exist together but are not combined chemically. Components of a mixture can be separated by physical processes. If you mix S and Fe how would you go about separating them? (bp S = 445 oC) ho Distillation separates water (H2O) from salt (NaCl) Microscopic View of the 3 States of Water 2H2 + O2 ? 2H2O rxn Measurement in Chemistry Measurements - are used to communicate information. A measurement consists of a number and an appropriate unit. Examples: 125?C; 10.0 kg; 10.0 mg Metric Units - SI Units Metric units are based on powers of 10. SI units are a set of metric units used preferentially in scientific measurements (International System). SI Units (Metric Units) Prefixes Prefixes Example: Length measurements Giga - G 109 1Gm=109 m Mega- M 106 1Mm=106 m Kilo- k 103 1km=103 m Centi- c 10-2 1cm=10-2 m Milli- m 10-3 1mm=10-3 m Micro- ? 10-6 1?m = 10-6 m Nano- n 10-9 1nm=10-9 m Pico- p 10-12 1pm=10-12 m SI Units (Metric Units) Prefixes Relationships between prefixes: 1cm = 10-2 m or 102 cm = 1 m 1mm = 10-3 m or 103 mm = 1 m 1?m = 10-6 m or 106 ?m = 1 m 1nm = 10-9 m or 109 nm = 1 m 1pm = 10-12 m or 1012 pm = 1 m SI Units (Metric Units) Derived Units SI-Derived Units Volume: (length x length x length) 1 mL = 1 cm3 SI Units (Metric Units) Derived Units Density Units: (mass/Volume) kg/m3 g/cm3 g/mL g/L Pb Al 11.34 g/cm3 2.70 g/cm3 Density = Mass/Vol Carbon dioxide gas is more dense than helium gas. Why? CO2 He Density = Mass/Vol Water is more dense than ice. Why? ICE WATER Unit Conversions Example: Convert 416 nm to meters Unit Conversions Example: Convert 416 nm to meters Answer: 4.16x10-7 m Unit Conversions: Remember units and SF! Convert 65 miles per hour to meters per second. (1 mile = 1.6093 km) Answer: 29 m/s Unit Conversions Practice! You do not need to memorize any of the English to metric conversion factors, such as 2.54 cm/inch. You do need to know the metric (SI) conversion factors You do need to know how to convert temperature values between Celsius and Kelvin.
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