Ch. 1 - Matter, Measurement & Problem Solving

Scientific and Standard Notation

Scientific notation is a method for expressing very large or very small numbers using powers of ten. Standard notation is the usual way numbers are written.

• Scientific Notation: Numbers are written as , where and is an integer.

• Standard Notation: Numbers are written out in full, without exponents.

• Example: in scientific notation is .

Significant Figures

Significant figures (sig figs) are the digits in a measurement that are known with certainty plus one digit that is estimated.

• Counting Significant Figures: All nonzero digits are significant; zeros between nonzero digits are significant; leading zeros are not significant; trailing zeros are significant only if there is a decimal point.

• Rules in Calculations: For multiplication/division, the result should have the same number of sig figs as the measurement with the fewest sig figs. For addition/subtraction, the result should have the same number of decimal places as the measurement with the fewest decimal places.

• Example: (rounded to 2 sig figs).

Temperature Conversions

Temperature can be measured in Celsius (°C), Kelvin (K), and Fahrenheit (°F). Conversion between these scales is often required.

• Celsius to Kelvin:

• Celsius to Fahrenheit:

• Fahrenheit to Celsius:

• Example:

Unit Conversions

Unit conversions are essential for solving chemistry problems, especially when dealing with different units of measurement.

• Conversion Factors: Use ratios to convert from one unit to another.

• Units2 and Units3: When converting squared or cubed units, apply the conversion factor the appropriate number of times.

• Example:

SI Prefixes

SI prefixes indicate multiples or fractions of units. Knowing the prefix and its exponent is crucial.

• Common SI Prefixes:

• Example:

Density

Density is a physical property defined as mass per unit volume. It is often used in laboratory experiments.

• Formula:

• Units: Commonly or

• Example: If a sample has a mass of and a volume of , its density is .

Ch. 2 - Atoms & Elements

Basic Components of the Atom

An atom consists of three fundamental subatomic particles: protons, neutrons, and electrons. Their arrangement is described by the nuclear model.

• Protons: Positively charged, located in the nucleus.

• Neutrons: Neutral, located in the nucleus.

• Electrons: Negatively charged, located outside the nucleus in electron clouds.

• Example: A carbon atom has 6 protons, 6 neutrons, and 6 electrons.

Isotopic Symbols

Isotopic symbols represent specific isotopes of elements, indicating the number of protons and neutrons.

• Format: , where is the mass number, is the atomic number, and is the element symbol.

• Example: represents carbon-12.

• Finding Elemental Symbol: Use the atomic number to identify the element on the periodic table.

Formation of Ions

Ions are formed when atoms gain or lose electrons, resulting in a net charge.

• Cations: Formed by loss of electrons; positively charged.

• Anions: Formed by gain of electrons; negatively charged.

• Effect on Subatomic Particles: The number of protons remains unchanged; the number of electrons changes according to the charge.

• Example: has 11 protons and 10 electrons.

Lab Techniques and Procedures (Additional info)

Density Measurement in Laboratory

Density is often determined experimentally by measuring mass and volume of a sample.

• Procedure: Measure mass using a balance; measure volume using a graduated cylinder or displacement method.

• Calculation: Use the formula .

• Application: Used to identify substances or assess purity.

Additional info: Academic context was added to expand brief points and provide examples, formulas, and explanations for self-contained study notes.