I’mChapter 1 Lec. Slides

Chapter 1: Matter, Measurements, and Calculations

Introduction

Authors: Seager, Slabaugh, HansenEdition: 9thPublisher: Cengage Learning (2018)

Learning Objectives

• Define matter and its properties.

• Distinguish between physical and chemical properties and changes.

• Classify matter (heterogeneous/homogeneous; solution/pure substance; element/compound).

• Utilize measurement units effectively.

• Convert metric system measurements.

Matter and Its Properties

Matter: Anything that has mass and occupies space. It exists in various states, including solid, liquid, and gas, each displaying unique properties due to the arrangement of particles.

Mass: A measurement of matter's quantity; it remains constant regardless of location, which is fundamental in scientific studies as it provides a standard measure.Example: An object with a mass of 10 kg on Earth will have the same mass of 10 kg on the Moon.

Weight: A measurement of the gravitational force exerted on an object; it varies by location due to differences in gravitational pull.Example: An object's weight is 16 pounds on Earth but only about 2.7 pounds on the Moon, highlighting the importance of distinguishing between mass and weight in calculations and physics.

Properties of Matter

• Physical Properties: Observable/measurable characteristics that do not change the substance’s composition.Examples: Color, size, density, melting point, and boiling point. These properties are essential for identifying substances and predicting their behavior in different environments.

• Chemical Properties: Characteristics that become evident only when a chemical reaction occurs, demonstrating the substance's ability to transform into different substances.Example: The flammability of paper or the reactivity of iron with oxygen to form rust.

Changes in Matter

• Physical Changes: Changes that do not alter the composition of the substance.Example: Cutting paper, boiling water, or dissolving sugar in water. These changes are usually reversible.

• Chemical Changes: Changes that result in the formation of new chemical substances, indicating a change in composition.Example: Burning magnesium or baking a cake, where ingredients undergo a transformation and cannot easily revert to their original form.

Classification of Changes

Physical and chemical changes can be distinguished based on whether or not the composition of the material is altered.Example 1.1: In a lab activity, students may burn a match (chemical change), melt iron (physical change), crush limestone (physical change), and explore other examples to categorize them correctly.

Molecules and Atoms

• Molecule: The smallest particle of a pure substance that retains its properties. Molecules can consist of one type of atom (e.g., O₂ for oxygen) or different types (e.g., H₂O for water).

• Atom: The basic unit of matter that cannot be subdivided chemically; it forms the foundation for all substances.

Dalton's Atomic Theory

• Matter is composed of atoms, which are indivisible.

• Elements contain atoms that are identical in mass and properties.

• Compounds consist of two or more different types of atoms.

• In chemical reactions, atoms rearrange; no atoms are created or destroyed.

Types of Molecules

• Diatomic Molecules: Composed of two atoms (e.g., H₂, N₂).

• Triatomic Molecules: Consist of three atoms (e.g., CO₂).

• Polyatomic Molecules: More than three atoms (e.g., O₃).

• Homoatomic: Made of one type of atom (e.g., O₂).

• Heteroatomic: Composed of two or more types of atoms (e.g., H₂O).

Mixtures and Pure Substances

• Mixtures: Composed of two or more substances that retain their individual properties and can be physically separated (e.g., salad, air).

• Homogeneous Mixtures: Uniform composition and properties throughout (e.g., saltwater).

• Heterogeneous Mixtures: Composition and properties vary within the sample (e.g., muddy water).

• Pure Substances: Have consistent composition and definite traits that cannot be separated by physical means (e.g., gold, distilled water).

Metric System and Measurements

• Measurements consist of a numeric value and a unit (e.g., gallons, Celsius).

• The Metric System features units based on multiples of ten, facilitating easy conversions. Basic metric units include:

  • Length: meter (m)

  • Mass: kilogram (kg)

  • Volume: liter (L)

  • Temperature: Celsius (°C)Examples: 1 meter is equal to 100 centimeters; 1 liter equals 1000 milliliters.

Scientific Notation

Used for expressing large or small numbers in a compact form as M × 10^n, where M is a number between 1 and 10, and n is an integer indicating the power of ten (positive for multiples and negative for fractions).

Significant Figures

Reflect the precision of measurements; they include all certain digits plus one estimated digit. The treatment of zeros (leading, buried, trailing) affects their significance in calculations. When performing arithmetic operations, the number of significant figures in the result is determined by the input with the least significant figures.

Factor-Unit Method

A systematic approach for solving conversion problems using conversion factors. Key steps include:

1. Identify known quantities and set up the equality with the unknown.

2. Cancel out units systematically to simplify the expression.

3. Perform calculations to derive the final answer.

Calculation Examples

• Area: For a rectangle with sides of 1.5 m and 2.0 m, the area equals 3.0 m² (or 30,000 cm²).

• Volume: For a cylinder, the volume can be calculated using the area of the base multiplied by the height.

Practical Applications (Join Ins and Examples)

This section illustrates the application of learned concepts through practical examples, such as calculating densities, percentages, and conversions. Activities include identifying physical changes, performing metric conversions, and applying theoretical knowledge to real-world scenarios.

Temperature Scales and Conversions

Main temperature scales include Celsius, Fahrenheit, and Kelvin. Conversion formulas are essential in scientific work to allow for standardization across measurements.

Density

Density is defined as the mass of a substance divided by its volume (density = mass/volume) and is crucial in identifying substances. Examples of density calculations are provided to show how to determine the volume or mass based on known measurements.

Conclusion

Understanding the properties of matter, the types of changes they undergo, and the importance of accurate measurement and calculation is fundamental in chemistry. Proper application of the scientific method, including reliability in measurements, adherence to significant figures, and effective use of conversion factors, enhances scientific practice.