Chapter 1 Zumdahl Chemistry 9th Edition PDF

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Chapter 1: Chemical Foundations 1.1 Chemistry: An Overview Scanning tunneling microscope(STM): uses an electron current from a tiny needle to probe the surface of a substance Macroscopic world: objects we can visibly see(cars, tables, oceans, etc.) Microscopic world: beyond the visible eye(atoms + molecules) -substances in the universe are made from 100 different kinds of atoms -a water molecule is composed of 2 hydrogen atoms and one oxygen atom

-when an electric current passes through it, water is split into hydrogen and oxygen. These chemical elements themselves exist naturally as diatomic(two-atom) molecules.

-we can represent the decomposition of water to its component elements, hydrogen and oxygen

-requires 2 molecules of water to create the correct number of oxygen and hydrogen atoms to allow for the formation of the 2 atom molecules 2 fundamental concepts of chemistry: 1. Matter is composed of various types of atoms 2. One substance changes to another by reorganizing the way the atoms are attached to each other

Science: A Process for Understanding Nature and Its Changes 1. Making observations(collecting data) 2. Suggesting a possible explanation(formulating a hypothesis) 3. Doing experiments to test the possible explanation(testing the hypothesis) -referred to as the scientific method

1.2 The Scientific Method

Scientific Models Theory: often called a model, a set of tested hypotheses that gives an overall explanation of some natural phenomenon -an interpretation: a possible explanation of why nature behaves in a certain way -change as more information becomes available -human inventions -represent attempts to explain observed natural behavior in terms of human experiences -an educated guess Observation: something that is witnessed and can be recorded Natural Law: when a parallel observation applies to many different systems, a summary of observed behavior Law of Conservation of Mass: the total mass of materials is not affected by a chemical change in those materials

1.3 Units of Measurement -a quantitative observation always consists of a number and a scale(a unit) -English system used in the U.S. and the metric system used by the rest of the world

SI system: based on the metric system and units derived from the metric system

Mass: a measure of the resistance of an object to a change in its state of motion

-mass is measured by the force necessary to give an object a certain acceleration Weight: the force that gravity exerts on an object to measure its mass -varies with the strength of the gravitational field

1.4 Uncertainty in Measurement -almost always record data with certain digits and the first uncertain digit present in the data

Precision and Accuracy Accuracy: the agreement of a particular value with the true value Precision: the degree of agreement among several measurements of the same quantity -reflects the reproducibility of a given type of measurement Random error: a measurement has an equal probability of being a high or low -occurs in estimating the value of the last digit of a measurement Systematic error: occurs in the same direction each time: it is either always high or always low

1.5 Significant Figures and Calculations

1.6 Learning to Solve Problems Systematically 1. What is my goal? Where am I going? 2. Where am I starting? What do I know? 3. How do I get there?

1.7 Dimensional Analysis

-make sure to have the units cancel when you are converting to a desired unit -always remember where you want to end up, cancel the units on the way -when there are 2 units to convert, focus on the one with more steps and then do the other conversion

1.8 Temperature Temperature(Kelvin) = temperature(Celsius) + 273.15 Temperature(Celsius) = temperature(Kelvin) - 273.15 Celsius = (Fahrenheit - 32)*5/9 Fahrenheit = Celsius*9/5 + 32 -when converting from fahrenheit to kelvin, have to go from fahrenheit→ celsius → kelvin

1.9 Density Density: the mass of substance per unit volume of the substance D = mass/volume

11.10 Classification of Matter Matter: anything occupying space and having mass Solid: rigid, has a fixed volume and shape Liquid: has a definite volume, no specific shape Gas: has no fixed volume or shape; takes on the shape and volume of its container -highly compressible, easy to decrease the volume of a gas Mixtures: Homogenous: having visibly indistinguishable parts Heterogeneous: having visibly distinguishable parts -a homogeneous mixture is called a solution Pure substance: one with constant composition

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