Chap 1,2&3 Review Honors Chemistry

Nature of Science Attempt to explain the Natural occurring phenomena of the Universe by logical means. Study of Matter and Energy is The Science of Chemistry

Rules for assigning significance to a digit: 1. Digits other than zero are always significant. 2. Rules about zeros: a. Final zeros after a decimal point are always significant. b. Zeros between two other significant digits are always significant. c. Zeros used only to space the decimal are never significant.

Significant Digits Multiply/Division- Least number of Digits 23.475 g / 8.7 cm3 2 digits in the answer 2.7 g/cm3 Addition/Subtraction- Least number of Decimal Places 23.456 g + 15.8578 g + 21.2 g 1 decimal place in the answer 60.5 g

SI Units Mass- Kilogram - kg Time- Second- s Length- Meter - m Electric Current- Ampere- A Temperature- Kelvin - K Amount of substance - mole - mol

Conversion Bar n u m c d base da h k M G T 10-9 10-6 10-3 10-2 10-1 1 101 102 103 106 109 1012

Precision vs. Accuracy Precision- how close a set of measurements are to each other, all within acceptable degree of uncertainty Determined by the individual Accuracy - How close a measurement is to the objects true value Determined by the measuring instrument

Matter and Energy Different sides of the same coin Matter- the substance of the universe Energy- the capacity to do work Potential energy - stored energy Chemical Energy is stored in chemical bonds Kinetic energy - energy of motion

Heat The sum total of kinetic energy, KE, of the particles in a sample of matter Average KE ~ Temperature

Endothermic and Exothermic Endothermic - energy is absorbed during a chemical or physical change Feels cold Example Physical - melting ice Chemical - cold pack Exothermic - energy is released during a chemical or physical change Feels Hot Physical - making ice Chemical - Iron changing to rust

Mass vs. Weight Mass amount of matter in a substance Amount of matter in an object is constant Weight amount of force on a substance Force can change the weight but not the amount of matter

Properties of Matter Chemical Properties - change the substance, can not be reversed by physical means Physical Properties - change the appearance or state of the substance and can be reversed by physical means

Properties of Matter Examples of Chemical Change Produces heat or light Produces new substance Examples of Physical Change Change in state of matter Changes in physical size or shape

Intensive vs. Extensive Properties Intensive Properties DO NOT depend on the amount of matter in a substance Density Extensive Properties Do depend on the amount of matter in a substance Mass or volume

States of Matter Solid Liquid Gas Plasma Volume and shape Minimal molecular kinetic energy Liquid Volume , no shape Moderate molecular kinetic energy Gas No volume or shape Maximum kinetic energy Plasma Striped of electrons found in stars or star like conditions

Mixtures Mixtures can be separated by physical means I.e. Distillation, Screening, Gravity Homogeneous Mixture Consist of solute and solvent Appears to be a single substance Heterogeneous Mixture Phases can be distinguished

Pure Substances Consists of one type of substance Element Compound A single type of matter Compound A mixture of elements in a definite ratio Water is 2 parts hydrogen to one part oxygen, H2O, everywhere in the Universe

Scientific Method Observation Hypothesis Experimentation New Hypothesis Theory Law

Observation Observance of natural occurring phenomena A Fact Qualitative Non-numerical description Subjective Quantitative Numerical Description Objective

Hypothesis The best explanation of a natural occurring phenomenon Testable Falsifiable States observation (if) and makes prediction (then)

A model Theory Verbal, mathematical or computer generated A set of tested Hypothesis that provides an overall explanation of a natural occurring phenomena A model Verbal, mathematical or computer generated

Law A measurable summary of natural occurring phenomena General Summary of Universal Events

Density Measurement of mass per unit volume (space) D=m/v