Chapter E and 1 quiz review

Chapter E Essentials: Units, Measurement, and Problem Solving

Units of Measurement

  • Importance of units in chemistry as standard quantities for specifying measurements.

  • Two common unit systems:

    • Metric system: Used globally.

    • English system: Used primarily in the U.S.

Table E.1: SI Base Units

  • Length: Meter (m)

  • Mass: Kilogram (kg)

  • Time: Second (s)

  • Temperature: Kelvin (K)

  • Amount of Substance: Mole (mol)

  • Electric Current: Ampere (A)

  • Luminous Intensity: Candela (cd)

important conversions to know for quiz

  • 1 L = 1000mL

  • 1 km= 1000g

  • 1m= 100 cm

The Meter: A Measure of Length

  • The meter (m) is 39.37 inches, slightly longer than a yard (36 inches).

  • Important conversions:

    • 1 m = 100 cm

    • 1 m = 1000 mm

    • 1 km = 1000 m

The Kilogram: A Measure of Mass

  • Mass measures the quantity of matter in an object.

  • SI unit: Kilogram (kg)

    • Equivalence: 1 kg = 2 lb 3 oz

  • Alternative mass unit: Gram (g)

    • 1 g = 1/1000 kg

  • Weight measures gravitational pull on mass.

The Second: A Measure of Time

  • Represents the duration of an event.

  • SI unit: Second (s)

Volume

  • The space a substance occupies; SI unit is m³, commonly expressed in liters (L), milliliters (mL), and cm³.

The Kelvin: A Measure of Temperature

  • Kelvin (K) is the SI unit of temperature.

  • Equation to find celcius: C= (Farenheit-32)/1.8

  • equation to find kelvin: K= celsius -273.15

  • Measures average kinetic energy of atoms/molecules.

  • Thermal energy flows from hotter to colder objects.

Absolute Temperature Scale

  • 0 K is absolute zero, the coldest temperature where molecular motion virtually stops.

Temperature Scales

  • Fahrenheit (°F): Degree size is five-ninths that of Celsius (°C).

  • Celsius (°C) and Kelvin (K) are equivalent in degree size.

  • Temperature conversion methods outlined.

Precision and Accuracy

  • Accuracy: Closeness of measured value to actual value.

  • Precision: Closeness of repeated measurements.

Counting Significant Figures

  • Significant figures reflect the precision of a measurement.

  • Instrument precision affects measurements and subsequent calculations.

  • Guidelines for significant figures include:

    • Nonzero digits are always significant.

    • Interior zeros are significant.

    • Leading zeros are not significant.

    • Trailing zeros may or may not be significant based on context.

Exact Numbers

  • Exact numbers have an unlimited number of significant figures, such as counts or defined quantities.

Rules for Calculations

  • Multiplication/Division Rule: Result carries the same significant figures as the factor with the fewest.

  • Addition/Subtraction Rule: Result carries the same decimal places as the least precise quantity.

Rules for Rounding

  • Round down if the last digit dropped is 4 or less; round up if 5 or more.

Rounding in Multistep Calculations

  • the last order of operation determines which rule applies in terms of significant figures.

Energy

  • Energy: Capacity to do work—depends on force applied over distance.

  • Kinetic Energy: Related to the motion of an object.

  • Potential Energy: Related to position or composition of an object. also known is resting state.

  • Thermal Energy: A type of kinetic energy from motion of atoms/molecules.

Summarizing Energy

  • The law of conservation of energy states energy is never created or destroyed.

  • Systems with high potential energy will change to lower energy states, releasing energy.

Energy Conversion Factors

Table E.5

  • 1 calorie (Cal) = 4.184 joules (J)

  • 1 Calorie (Cal) or kilocalorie (kcal) = 1000 cal = 4184 J

  • 1 kilowatt-hour (kWh) = 3.60 x 10^6 J

Chapter 1

Properties of Matter

  • The properties of matter are fundamentally determined by the properties of molecules and atoms.

  • Atoms and molecules influence how matter behaves, making them the building blocks of ordinary matter.

  • Free atoms are rare in nature; they typically bind together in specific geometrical arrangements to form molecules.

Atoms and Elements

  • An atom is the smallest identifiable unit of an element.

  • There are approximately 91 different naturally occurring elements and over 20 synthetic elements, which are not found in nature.

Classification of Matter

  • Matter is defined as anything that occupies space and possesses mass.

  • It can be classified based on its state (solid, liquid, gas) and its composition.

    • States of Matter:

      • Solid, Liquid, Gas

    • State Classifications:

      • Solid: Atoms or molecules tightly packed in fixed locations.

      • Liquid: Atoms or molecules close together but free to move relative to one another.

      • Gas: Atoms or molecules far apart and free to move, making them compressible.

Solid Matter

  • Characteristics of solid matter:

    • Atoms or molecules are fixed near each other with very little kinetic energy, resulting in a fixed volume and rigid shape.

    • Examples include ice, aluminum, and diamond.

  • Solid matter can be:

    • Crystalline: Atoms or molecules organized in a repeating pattern (e.g., table salt, diamond).

    • Amorphous: Lacking long-range order (e.g., glass and plastic).

Gaseous Matter

  • Gases consist of atoms or molecules with significant space between them, allowing them to move freely relative to one another, making them compressible.

Classification of Matter by Components

  • Matter can also be classified based on its composition into elements, compounds, and mixtures.

  • Pure Substance vs Mixture:

    • A pure substance has a uniform composition and cannot be separated into different components by physical means.

    • A mixture is composed of two or more substances that retain their individual properties and can vary in composition.

Classification of Pure Substances

  • Element: A fundamental substance that cannot be chemically broken down into simpler substances.

    • Composed of a single type of atom (e.g., helium).

  • Compound: A substance formed from two or more elements in fixed proportions.

    • Most elements are reactive and combine to form compounds (e.g., water, sugar).

Classification of Mixtures

  • Mixtures are categorized into:

    • Heterogeneous Mixtures: visually distinguishable, like fruit salad

    • Homogeneous Mixtures: Composition is uniform throughout (e.g., salt water mixed).

The Scientific Approach to Knowledge

  • Key characteristics of the scientific method:

    • Observation

    • Formulation of hypotheses

    • Experimentation

    • Formulation of laws and theories.

Modern Atomic Theory and Laws

  • The atomic theory, stating that all matter is composed of atoms, evolved from observations and laws:

    • Laws guiding this theory:

      • The law of conservation of mass

      • The law of definite proportions

      • The law of multiple proportions

The Law of Conservation of Mass

  • stating matter is neither created nor destroyed in chemical reactions, ensuring total mass remains constant during reactions.

The Law of Definite Proportions

  • indicates all samples of a specific compound have the same proportions of elements by mass

    • water will always have 2 H and 1 O

The Law of Multiple Proportions

  • when two elements form multiple compounds, the masses of one element that combine with a fixed mass of the other can be expressed as a ratio of small whole numbers (e.g., carbon monoxide vs carbon dioxide).

The Neutrons

  • Neutrons have a mass similar to protons but no charge, affecting atomic mass.

  • only protons and neutrons affect atomic mass. electrons do not.

Subatomic Particles

  • Atoms consist of three primary subatomic particles:

    • Protons

    • Neutrons

    • Electrons

Elements and Their Protons

  • The identity of an atom is defined by the number of protons in its nucleus, known as its atomic number (Z).

  • atomic number = the number of protons in nucleus

Isotopes and Mass Number

  • Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons.

  • The mass number (A) is the sum of protons and neutrons.

Ions: Gaining or Losing Electrons

  • Neutral atoms have an equal number of protons and electrons; losing or gaining electrons results in ions.

    • Cations: Positively charged ions (e.g., Na+).

    • Anions: Negatively charged ions (e.g., F–).