General Chemistry Study Guide: Measurement, Matter, Atomic Structure, and Electron Configuration

Mathematical Operations and Functions

Significant Figures and Scientific Notation

Understanding significant figures and scientific notation is essential for accurately reporting and manipulating scientific measurements. These concepts help quantify precision and uncertainty in experimental data.

• Significant Figures (Sig Figs): The digits in a measurement that are known with certainty plus one digit that is estimated. The number of significant figures reflects the precision of the measurement.

• 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.

• Operations with Significant Figures:

  • Multiplication/Division: The result should have the same number of significant figures as the measurement with the fewest significant figures.

  • Addition/Subtraction: The result should have the same number of decimal places as the measurement with the fewest decimal places.

• Scientific Notation: A method for expressing very large or very small numbers. The format is $a \times 10^n$, where $a$ is a number between 1 and 10, and $n$ is an integer.

• Converting Between Standard and Scientific Notation:

  • Move the decimal point to create a number between 1 and 10; count the number of places moved to determine the exponent.

• Example: 0.00045 in scientific notation is $4.5 \times 10^{-4}$.

Chemical Quantities & Aqueous Reactions

Metric Units and Unit Conversions

The metric system is used universally in science to measure mass, length, volume, and time. Understanding unit conversions is crucial for solving chemistry problems.

• Base Metric Units:

  • Gram (g): mass

  • Meter (m): length

  • Liter (L): volume

  • Second (s): time

• Metric Prefixes: Used to indicate multiples or fractions of base units.

  • Kilo- ($10^3$)

  • Deci- ($10^{-1}$)

  • Centi- ($10^{-2}$)

  • Milli- ($10^{-3}$)

  • Micro- ($10^{-6}$)

  • Nano- ($10^{-9}$)

• Conversion Factors: Ratios used to convert between units.

  • Example: $1 \text{ km} = 1000 \text{ m}$

• Unit Conversions with Exponents: When converting units with exponents, apply the conversion factor to each dimension.

  • Example: $100 \text{ cm}^3$ to $\text{m}^3$:

    • $1 \text{ cm} = 0.01 \text{ m}$

    • $100 \text{ cm}^3 = 100 \times (0.01 \text{ m})^3 = 100 \times 0.000001 \text{ m}^3 = 0.0001 \text{ m}^3$

• Compound Unit Conversions: Convert each unit separately, then combine.

  • Example: $\text{m/s}$ to $\text{km/hr}$:

    • $1 \text{ m/s} = 3.6 \text{ km/hr}$

Intro to General Chemistry

Phases and Classification of Matter

Matter exists in three primary phases and can be classified based on its composition and properties.

• Phases of Matter:

  • Solid: Definite shape and volume; particles are closely packed and vibrate in place.

  • Liquid: Definite volume but no definite shape; particles are less tightly packed and can move past each other.

  • Gas: No definite shape or volume; particles are far apart and move freely.

• Phase Changes:

  • Melting: Solid to liquid

  • Freezing: Liquid to solid

  • Vaporization: Liquid to gas

  • Condensation: Gas to liquid

  • Sublimation: Solid to gas

  • Deposition: Gas to solid

• Classification of Matter:

  • Element: Pure substance consisting of one type of atom.

  • Compound: Pure substance consisting of two or more types of atoms chemically bonded.

  • Homogeneous Mixture: Uniform composition throughout (e.g., salt water).

  • Heterogeneous Mixture: Non-uniform composition (e.g., salad).

• Writing Chemical Formulas: Use element symbols and subscripts to indicate the number of each atom.

  • Example: Water is $\text{H}_2\text{O}$ (2 hydrogen atoms, 1 oxygen atom).

• Names and Symbols of Elements: Know elements 1-36 plus gold (Au), silver (Ag), tin (Sn), iodine (I), and lead (Pb).

Atoms & Elements

Atomic Structure and Isotopes

Atoms are composed of subatomic particles and can exist as different isotopes. Understanding atomic structure is fundamental to chemistry.

• Subatomic Particles:

  • Proton: Positive charge (+1), found in the nucleus.

  • Neutron: Neutral charge (0), found in the nucleus.

  • Electron: Negative charge (-1), found outside the nucleus.

• Atomic Number ($Z$): Number of protons in the nucleus; defines the element.

• Mass Number ($A$): Total number of protons and neutrons in the nucleus.

• Isotopes: Atoms of the same element with different numbers of neutrons (different mass numbers).

• Atomic Notation: $^{A}_{Z}\text{X}$, where $X$ is the element symbol, $A$ is the mass number, and $Z$ is the atomic number.

• Calculating Atomic Mass: Weighted average of isotopic masses based on their abundance.

  • $\text{Atomic mass} = \sum (\text{isotope mass} \times \text{fractional abundance})$

Quantum Mechanics

Light, Energy, and Electron Transitions

Light exhibits both wave and particle properties. The energy of light is related to its wavelength and frequency, and electron transitions between energy levels involve absorption or emission of energy.

• Wavelength ($\lambda$): The distance between two consecutive peaks of a wave.

• Frequency ($\nu$): The number of wave cycles per second.

• Relationship: $c = \lambda \nu$, where $c$ is the speed of light.

• Energy of Light: $E = h \nu$, where $h$ is Planck's constant.

• Electron Transitions: Electrons absorb energy to move to higher energy levels and emit energy when returning to lower levels.

Quantum Mechanics

Electron Configuration

Electron configuration describes the arrangement of electrons in an atom. It is essential for understanding chemical properties and reactivity.

• Full Electron Configuration: Lists all occupied orbitals in order of increasing energy.

  • Example: Oxygen ($Z=8$): $1s^2 2s^2 2p^4$

• Core/Noble Gas Notation: Uses the symbol of the nearest noble gas to represent core electrons.

  • Example: Sodium ($Z=11$): $[\text{Ne}] 3s^1$

Atoms & Elements

Table: Subatomic Particles

The following table summarizes the properties of the three main subatomic particles:

Particle	Charge	Location
Proton	+1	Nucleus
Neutron	0	Nucleus
Electron	-1	Outside nucleus

Atoms & Elements

Table: Common Elements and Symbols

The following table lists the names and symbols of elements 1-36 plus gold, silver, tin, iodine, and lead:

Element Name	Symbol
Hydrogen	H
Helium	He
Lithium	Li
Beryllium	Be
Boron	B
Carbon	C
Nitrogen	N
Oxygen	O
Fluorine	F
Neon	Ne
Sodium	Na
Magnesium	Mg
Aluminum	Al
Silicon	Si
Phosphorus	P
Sulfur	S
Chlorine	Cl
Argon	Ar
Potassium	K
Calcium	Ca
Scandium	Sc
Titanium	Ti
Vanadium	V
Chromium	Cr
Manganese	Mn
Iron	Fe
Cobalt	Co
Nickel	Ni
Copper	Cu
Zinc	Zn
Gallium	Ga
Germanium	Ge
Arsenic	As
Selenium	Se
Bromine	Br
Krypton	Kr
Gold	Au
Silver	Ag
Tin	Sn
Iodine	I
Lead	Pb

Additional info: Academic context and examples have been added to ensure completeness and clarity for exam preparation.