01.01 Science of Chemistry:

Chemistry… a Science:

Chemistry is the study of the composition and structure of materials and the changes they undergo.

Phenomena: observable events or occurrences; plural of phenomenon

In order for something to be considered science, it must be based on empirical observations, experimentation, and explanations based on logical reasoning.

Characteristics of Science:

• Observable: Science attempts to explain natural phenomena by analyzing and observing the world and testing ideas about it.

• Testable: Investigations must produce empirical evidence that can be observed or measured to be considered science.

• Replicable: Empirical evidence can be replicated, or reproduced, and verified by other scientists if they conduct the same tests under the same conditions.

• Reliable: The more an experiment is repeated, with the same outcomes, the more reliable the evidence becomes.

• Flexible: As new information is discovered, new evidence can add to current evidence, allowing scientists to improve their theories.

Science Know-it-All:

Two things to look for when determining if a question can be answered by science:

1. If the question is asking about an opinion, it cannot be answered by science.

2. If the question cannot be tested, it cannot be answered by science.

Method Madness:

A scientific method is a series of steps for investigating questions and testing ideas.

• Ask a Question:

  • For any question you can imagine, if it's testable, you can use science to find the answer.

• Do Background Research:

  • Previous investigations into your topic may lead you to new questions that need answers

• Construct a Hypothesis:

  • A hypothesis is a prediction or a tentative explanation based on research or observation.

  • Forming a hypothesis involves creativity to anticipate what will happen because of something else.

• Test with an Experiment:

  • An experiment allows you to test your hypothesis to determine if it is a correct or incorrect prediction of the outcome.

  • There are many ways to test a hypothesis, but every experiment should have at least one variable that changes while the others stay the same or are controlled.

• Analyze Data and Draw Conclusions:

  • Once an experiment is complete, the results need to be analyzed to determine if the outcome supports the hypothesis.

Reliable Science:

Reliable science includes empirical evidence and results from experiments that can demonstrate replication and repetition.

Sources of poor science include experimental errors or missing components of the scientific method.

Characteristics of “Bad Science”:

• No Control

• No Repeats

• Bias

01.02 Measuring Matter:

Measuring Matter:

All measurements are made up of two parts: a number and a unit.

Volume: the amount of space a substance or object occupies

• Gasoline by the gallon

• Soda by the liter

Mass: a measure of the amount of matter in an object.

• Mass of a person

• Mass of a paperclip

Mass is a measurement of how much matter makes up an object, while weight measures how much the force of gravity is acting on mass.

Systems of Measurements:

The U.S. customary system (commonly known as the English system) consists of measurements we use every day to describe how much we have, what size we want, how far we want to go, and more.

The metric system is a system of measuring units based on the power of 10. It is the preferred system used in science measurement.

Prefix Reference for Metric Units:

Le Système International des Unités (The International System of Units), abbreviated as SI units, is the primary system used by scientists and engineers.

Converting Units:

U.S. Customary Units of Measure:

Metric Units of Measure:

Time and Temperature:

Accuracy and Precision:

Accuracy: the closeness of a measurement to the true or accepted value.

• Refers to the closeness of a measurement to the true or accepted value.

Precision: the consistency of a set of measurements made of the same quantity in the same way.

• Refers to the consistency of a set of measurements made of the same quantity in the same way.

Significant Figures:

The significant figures in a measurement include all the digits known with certainty, plus one final digit that is estimated and uncertain.

Rules for Multiplication and Division:

• For multiplication and division, answers should be rounded off to the same number of total significant figures as the measurement with the fewest significant figures.

• If you are only given one measurement, the total number of significant figures in that measurement equals the total number of significant figures allowed in your final answer.

• Only measurements made with a specific instrument affect the number of significant figures allowed in the final answer. Conversion factors used to convert units do not affect the number of significant figures in the final answer.

Rules for Addition and Subtraction:

• For addition and subtraction, the answer should be rounded off so that the final digit is in the same place as the leftmost estimated place in the given measurements.

• The final answer cannot have more places after the decimal than any of the given measurements.

• The final answer cannot have a final digit, which represents the uncertain or estimated place, farther to the right than any of the final digits in the measurements used.

01.03 Honors Scientific Knowledge:

Pseudoscience

Sometimes a practice or belief claims to be science, but it does not follow the scientific method or is not proven reliable through experimentation. This is called pseudoscience.

Is it Valid?

Hidden phenomena refer to aspects or factors that are not immediately visible or apparent but have an impact on a situation or outcome. These can include underlying causes, motives, or influences that are not easily observable but play a significant role in shaping events or behaviors.

Theories and Hypotheses:

Within the body of scientific knowledge are two very important components: hypotheses and theories. Both types of scientific knowledge are developed using background research and can change over time using the scientific method. The difference is that scientific theories are well-tested hypotheses.

01.04 Properties of Matter:

States of Matter:

Physical Properties:

Physical properties: an observable and measurable physical characteristic of matter.

Extensive properties: a physical property that is dependent on sample size.

• Shape

• Volume

• Length

• Mass

Intensive properties: a physical property that is not dependent on sample size.

• Magnetism

• Density

• Melting/Boiling Points

• Color

Determining Density:

Density is a material's mass divided by its volume, or its mass per unit volume. It is an essential intensive property that involves how much space the particles of an object takes up.

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Chemical Properties:

Chemical properties: a substance's potential to undergo a reaction or chemical change because of its composition or bonding

Molecular composition: the number of atoms of each element that make up the molecules of a substance.

The molecular composition of a substance changes when it interacts with another substance.

01.05 Changes in Matter:

Physical vs. Chemical Changes:

What Change is It?:

Examples of Physical Changes:

• melting

• boiling

• freezing

• condensing

• breaking

• bending

• dissolving

In physical changes, molecules undergo a change in state or appearance without any change in their chemical composition. In chemical changes, molecules undergo a reaction that results in the formation of new substances with different chemical compositions.

Signs that indicate that a Chemical Reaction has taken place:

• production of flames

• color change

• bubbling or fizzing

• temperature change

• smoke

• production of light

• formation of a substance in a different state

Many of these observations could also be the result of a physical change, so it is important to determine if the resulting substances have different chemical properties than the original substances.

Phase Changes:

When a substance changes states, it undergoes a phase change. When a substance changes phases, the way the molecules are arranged and the space between them change.

• Evaporation occurs when a liquid changes to a gas.

• Condensation occurs when a gas changes to a liquid.

• Melting occurs when molecules that make up a solid get enough energy to overcome the forces holding them in place, a solid melts into a liquid.

• Freezing occurs when the molecules that make up a liquid lose enough energy and slow down, a liquid freezes to form a solid.

• Sublimation occurs when a solid changes directly into a gas.

• Deposition occurs when a gas changes into a solid.

01.06 Pure Substances and Mixtures:

Mixtures vs. Pure Substances:

All matter can be classified into two main categories: mixtures and pure substances.

Mixtures contain compounds and elements that can be physically separated from one another.

Pure substances made from compounds can only be chemically separated into the elements that make them up.

Properties of Matter:

Types of Solutions:

In a heterogeneous mixture, the composition is not uniform, or the same, throughout. In a homogenous mixture, the composition of the mixture is uniform throughout.

• Colloids contain microscopically insoluble particles suspended in another substance.

• Emulsions are homogeneous mixtures of two or more liquids that are normally not mixable.

• Solutions are homogeneous mixtures in which the solute is dissolved and distributed evenly within the solvent.

An electrolyte solution is created when a substance dissolves in a solvent, like water, and becomes electrically conductive.

Saturation refers to the point in a solution when no more solute can be dissolved in a solvent. This ratio is different for every solution. An unsaturated mixture still has capacity for more solute to dissolve in a solution. A saturated solution cannot dissolve any more solute. When a solution is supersaturated, the addition of heat has allowed more solute to dissolve into the solvent than normally possible.

Separating Mixtures:

Heterogeneous mixtures can be separated based on physical properties such as size, color, or magnetism. Homogeneous mixtures require a little more work to separate their components. Heat, pressure, and differences in density are some methods used to separate homogeneous mixtures.

Ways to separate mixtures:

• Magnets

• Filtration

• Centrifuge

• Evaporation

• Distillation

• Chromatography

01.07 Properties of Matter Lab:

Steps in the systematic process of experimentation:

• Detailed Process: Listing the materials and procedures seems simple enough, but missing a step can be disastrous.

• Experiment Variables: There are three types of variables in an experiment: controlled, independent, and dependent.

• Control Group: The control group allows scientists to compare the tested (experimental) group with the untested (control) group in order to validate their results.

Creating a Lab Report:

A science lab report allows scientists to organize and record the data of an experiment. It also lists all the materials and steps in an experiment so they can be followed by other scientists. This allows the results of the experiment to be validated through repetition.

Accurate Measurements:

• Graduated Measurement Tools

  • Graduated measuring tools are typically transparent plastic or glass. They have lines that measure a certain physical quantity, such as volume.

  • When using a graduated cylinder or beaker to measure volume, the liquid poured inside will slightly stick to the tool, creating a curve at the top of the liquid. This is called a meniscus.

  • You can measure the liquid by looking at which graduation mark the bottom of the meniscus touches.

• Digital Scales

  • To use a digital scale, follow these steps:

  • There are two types of digital scales: simple digital scales and analytical scales.

    1. Turn on and place the measuring tool (graduated cylinder, weigh boat, flask, etc.) onto the scale.

    2. Push the zero or tare button. This removes the mass of the container so that you only measure the mass of the substance.

    3. Add your substance and record the value.

• Balances

  • To use a balance, follow these steps:

    1. Place the measuring tool (graduated cylinder, weigh boat, flask, etc.) onto the scale. This will cause the tip of the balance to be above 0, meaning it is not balanced.

    2. You must slide the weighted bars across the beam until the arrow matches the 0 line. If the tip is above 0, then you need to slide the weights to the right. If the tip is below 0, then you need to move the weights left.

    3. Record the mass of your measuring tool. Now add your substance into the measuring tool.

    4. Complete the action of moving the weights until the needle lines up to the 0 again.

    5. Record the value. This mass is the mass of the tool plus the mass of the substance. If you only want the mass of the substance, you need to subtract.

    6. Keep in mind that the top beam is usually in values of 10 g, the second in values of 100 g, and the third in values of 1 g.