COMBINING Chapters 1 and 2

Thinking Like A Scientist CHAPTER 1 Thinking Like A Scientist

What are the steps to the scientific method? A scientific method is a logical, systematic approach to the solution of a scientific problem KEY QUESTION What are the steps to the scientific method? Observations, proposing and testing hypotheses, and developing theories (CONCLUSION) When senses are used to obtain information observations are being made The hypothesis is a proposed explanation to an observation

The experiment is a procedure that is used to test a hypothesis The variable that is changes in an experiment is called the independent variable (manipulated variable) The variable that is observed during an experiment is called the dependent variable (responding variable) A model is a representation of an object or event A theory is a well-tested explanation for a broad set of observations A scientific law is a concise statement that summarizes the results of many observations and experiments

Can a scientific theory ever become a scientific law. NO Can a scientific theory ever become a scientific law? NO! Theories are well supported explanations Laws are well supported descriptions

Can a scientific theory ever change? YES! New observations or experimental results may lead to evolutions of theories.

What is the importance of collaboration and communication in the world of science? Collaboration and communication allows the scientists to brainstorm from each others ideas and create successful outcomes.

All data from an experiment must be reported accurately, failure to do so results in a bias and inaccurate conclusion! BIAS????

Thinking Like A Scientist! Will Be COMPLETED IN CLASS! LET’S APPLY Thinking Like A Scientist! Will Be COMPLETED IN CLASS! *A constant is anything that remains the same during the experiment to ensure that only the independent variable is being changed *The control is what is being used to compare the results to

Chapter 2 Matter and Change

Properties of Matter 2.1

Identifying a Substance Any matter that has a uniformed and definite composition is called a substance Key Concept Explain why all samples of a substance have the same intensive properties. Every sample has the same composition. Physical property is a condition that can be observed or measured without making changes to the substance’s composition Examples of physical properties are hardness, conductivity, color, malleability, boiling point, melting point

Key Concept List the three common states of matter. solid, liquid, gas

Solids Solids have definite shapes and volumes It’s shape does not depend on the shape of the container These particles are packed tightly and stay in once place and vibrate, because of this solids are almost incompressible (hard to squeeze into a smaller space) When heated solids expand slightly

Liquids Liquids have indefinite shapes and fixed volumes The particles of a liquid are close, but not as close as those of solids, and are able to slide past each other from one area to another Liquids take the shape of their container It’s shape may change, but not it’s volume Like gases liquids are almost incompressible, and expand slightly when heated

Gases Takes the shape of its container Fills all available space Gases take the shape and volume of their container The particles have little to no attraction to each other Easily compressed (due to the space between the particles)

Physical Changes Physical change is a change in which the composition of the substance remains the same Key Concept Give 2 ways that physical changes may be classified: Reversible Irreversbile Words that describe physical changes: Boil, freeze, melt, condense reversible physical changes Break, split, grind, cut, crush  irreversible physical changes

MIXTURES 2.2

Classifying Mixtures Key Question How are mixtures classified? Heterogeneous mixtures or Homogeneous mixtures

Heterogeneous Mixtures Heterogeneous mixture is a mixture in which the composition is not uniformed throughout Homogeneous mixture is a mixture in which the composition is uniformed throughout The term phase is used to describe the part of a sample that has uniformed composition Heterogeneous mixtures contain two or more phases, where a homogeneous mixture will contain only one (single) phase

PRACTICE: Classifying Mixtures as Heterogeneous or Homogeneous See Study Guide

Elements and Compounds 2.3

Distinguishing and Compounds Substances may be classified as elements or compounds Element is the simplest form of matter Compound is made up of elements in a fixed proportion Key Concept Distinguish between elements and compounds? Compounds can be broken down into simpler substances (elements) by chemical means, where as elements can not be broken down into simpler substances. In order to break down a compound, the method used must involve a chemical change Chemical change is a change that produces matter with a different composition than the original substance The properties of compounds are different from the elements that make them up, the compound obtain a new set of properties

Distinguishing Substances and Mixtures Key Concept Explain how substances and mixtures can be distinguished. Fixed composition-substance (element or compound) Varying composition-mixture (contains two or more different elements and/or compounds)

Symbols and Formulas Symbols and chemical formulas are used by chemists to represent elements and compounds, respectively Chemical symbol is a one or two letter symbol used as shorthand to represent elements The second letter is always lowercase

Chemical Reactions 2.4

Explain what happens during a chemical change. Chemical Changes Burn, rot, rust, decompose, ferment, explode, and corrode are terms that are used to describe chemical changes Chemical property is the ability of a substance to undergo a chemical change Key Concept Explain what happens during a chemical change. The composition of matter always change. Chemical reaction one or more substances change into one or more new substances Reactant present at the beginning of the reaction Product what is produced during the chemical reaction

Recognizing Chemical Changes Key Concept List the four possible clues that a chemical reaction has taken place. Energy transformation Color change Production of gas Formation of a precipitate Precipitate is a solid that settles out of a liquid mixture

Conservation of Mass Key Question What is the relationship between the mass of the reactants and the mass of the products? EQUAL Law of conservation of mass is conserved in both chemical and physical reactions