Unit 1Introduction to Chemistry

World of ChemistryChapter 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 chemistryFor more career options see:http://www.acs.org/content/acs/en/careers/

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 problem2. Hypothesis – propose an explanation (sometimes

use “if, then” statement)3. Experiment – develop a strategy to test hypothesis4. 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

http://extensionengine.com/accuracy-precision/#.U_pba7ywIbo

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

http://misterguch.brinkster.net/graph.html

Bad graph

http://misterguch.brinkster.net/graph.html

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