Unit 1 Introduction to Chemistry World of Chemistry Chapter 1 Chemistry: An Introduction

Chapter Objectives: Identify the importance of studying chemistry Identify chemists’ role in the real world Identify how to study chemistry Define what chemistry is Identify and demonstrate the steps of the Scientific Method

Why is studying chemistry important? To help us… - develop medicines - make fireworks - develop fertilizer - to balance pH Who uses chemistry? – chemists!! – doctors – journalists – paint manufacturers – oceanographers – cosmetic companies Where else or who else do you think uses chemistry?

What do chemists do? Chemists can focus on a range of areas including… – materials science – biochemistry – astrochemistry – soil chemistry For more career options see:

As a student, how do I… ….benefit from this class? Answer questions you might already have about anything nature Develop problem solving skills – recognize and analyze a problem – draw conclusions from data, evidence Continue to develop and apply algebraic skills Develop science literacy skills Do really interesting experiments and use cool lab equipment ….study for this class? Memorize vocab and definitions take extra notes/ideas discussed in class Review notes frequently Learn the fundamentals, principal concepts Do practice problems!! – Identify patterns – simplify, simplify, simplify

What is chemistry? Chemistry: the study of the transformation of matter chemical vs. physical – how something reacts vs. how it physically looks chemical behavior ruled by the “invisible” world of atoms and subatomic particles Pencils are made of rubber, metal, wood, and graphite…what does this look like?

The microscopic world of pencils?

The Scientific Method Scientific method: a series of steps used to analyze and solve a problem observed in nature 1.Observation - identify a problem 2.Hypothesis – propose an explanation (sometimes use “if, then” statement) 3.Experiment – develop a strategy to test hypothesis 4.Analyze results 5.Draw conclusions/report results

What’s necessary for an experiment? Independent variable: manipulated by experimenter Dependent variable: measured by experimenter Control variable: unchanged, constant Not every experiment is required to have variables, usually for “if, then” hypothesis

Precision vs. Accuracy Multiple trials required to validate data (the more the better as long as you’re getting good data) Data should be both precise and accurate – precision: consistency in trials – accurate: how close to theoretical or accepted results

Analyzing data To determine the relationship between variables, it is often good to graphically represent data x axis – independent variable y axis – dependent variable type of graph depends on experiment (bar graph, line of best fit) Quantitative data – numerical measurements Qualitative data – descriptions

Good graph

Bad graph

Drawing conclusions Conclusions may not support hypothesis Theory – provides an explanation for observations (can be disproven) – Big Bang Theory for the origins of the universe Law – provides general statement about observations, does not explain “why” but cannot be disproven – Law of gravity