CHM 122 Exam I Study Guide: Matter, Atoms, and Introduction to Organic Chemistry

Chapter 1: Matter and Measurements

States of Matter

The three primary states of matter are solid, liquid, and gas. Each state has distinct physical properties.

• 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.

• Additional info: Plasma is a fourth state, but not typically covered in introductory GOB Chemistry.

Chemical Reaction Parts and Subscripts

Chemical reactions involve reactants and products. Subscripts indicate the number of atoms in a molecule.

• Reactants: Substances that undergo change.

• Products: Substances formed as a result of the reaction.

• Subscripts: Numbers written below and to the right of element symbols (e.g., H2O).

Foundation Units of Measurement

Measurements in chemistry use the SI (International System) units.

• Distance: Meter (m)

• Mass: Kilogram (kg) or gram (g)

• Volume: Liter (L) or milliliter (mL)

• Time: Second (s)

Metric System Conversions

The metric system uses prefixes to indicate multiples or fractions of units.

• Kilo- (k): 1,000 times the base unit

• Centi- (c): 1/100 of the base unit

• Milli- (m): 1/1,000 of the base unit

• Example: 1 km = 1,000 m; 1 cm = 0.01 m

Scientific Notation

Scientific notation expresses very large or small numbers using powers of ten.

• Format: $a \times 10^n$ where $a$ is a number between 1 and 10, and $n$ is an integer.

• Example: 0.00045 = $4.5 \times 10^{-4}$

Significant Figure Rules

Significant figures reflect the precision of a measurement.

• All nonzero digits are significant.

• Zeros between nonzero digits are significant.

• Leading zeros are not significant.

• Trailing zeros in a decimal number are significant.

• Example: 0.00450 has three significant figures.

Factor Label Calculation Setup (Dimensional Analysis)

Dimensional analysis uses conversion factors to solve problems involving units.

• Setup: Multiply by conversion factors so units cancel appropriately.

• Example: To convert 5.0 g to mg: $5.0 \text{ g} \times \frac{1000 \text{ mg}}{1 \text{ g}} = 5000 \text{ mg}$

Temperature Conversion

Temperature can be converted between Celsius, Fahrenheit, and Kelvin.

• Celsius to Fahrenheit: $F = (C \times \frac{9}{5}) + 32$

• Celsius to Kelvin: $K = C + 273.15$

• Fahrenheit to Celsius: $C = (F - 32) \times \frac{5}{9}$

• Kelvin to Celsius: $C = K - 273.15$

Density and Specific Gravity

Density is the mass per unit volume; specific gravity compares the density of a substance to water.

• Density: $\text{Density} = \frac{\text{Mass}}{\text{Volume}}$

• Specific Gravity: $\text{Specific Gravity} = \frac{\text{Density of substance}}{\text{Density of water}}$

• Example: If a liquid has a density of 1.2 g/mL, its specific gravity is $\frac{1.2}{1.0} = 1.2$

Chapter 2: Atoms and the Periodic Table

Atoms and Isotopes; Subatomic Particles

An atom consists of protons, neutrons, and electrons. Isotopes are atoms of the same element with different numbers of neutrons.

• Proton: Positively charged particle in the nucleus.

• Neutron: Neutral particle in the nucleus.

• Electron: Negatively charged particle orbiting the nucleus.

• Isotope: Same number of protons, different number of neutrons.

• Example: Carbon-12 and Carbon-14 are isotopes of carbon.

Atomic Mass Influenced by Isotopes

The atomic mass listed on the periodic table is a weighted average of all naturally occurring isotopes.

• Formula: $\text{Average Atomic Mass} = \sum (\text{Isotope Mass} \times \text{Fractional Abundance})$

Periodic Table

The periodic table organizes elements by increasing atomic number and groups elements with similar properties.

• Groups: Vertical columns; elements in the same group have similar chemical properties.

• Periods: Horizontal rows.

• Family Names: Alkali metals (Group 1), Alkaline earth metals (Group 2), Halogens (Group 17), Noble gases (Group 18).

Orbitals: s, p, d, f

Electrons occupy orbitals, which are regions of space around the nucleus.

• s orbital: Spherical shape; found in all periods.

• p orbital: Dumbbell shape; starts in period 2.

• d orbital: Complex shape; starts in period 4.

• f orbital: Even more complex; starts in period 6.

• Location: s-block (Groups 1-2), p-block (Groups 13-18), d-block (transition metals), f-block (lanthanides and actinides).

Electron Configurations and Orbital Diagrams (Elements 1-20)

Electron configuration shows the arrangement of electrons in an atom.

• Example: Oxygen (atomic number 8): $1s^2 2s^2 2p^4$

• Orbital diagram: Uses arrows to represent electrons in each orbital.

Valence Shell and Valence Electrons

The valence shell is the outermost electron shell; valence electrons are those in this shell and determine chemical reactivity.

• Example: Sodium (Na): 1 valence electron in the 3s orbital.

Electron Dot Symbols (Lewis Dot Symbols)

Lewis dot symbols represent valence electrons as dots around the element symbol.

• Example: For carbon: C with four dots around it.

Shapes of s and p Orbitals

• s orbital: Spherical

• p orbital: Dumbbell-shaped, oriented along x, y, and z axes

Introduction to Organic Chemistry

Covalent Bonds in Lewis Structures

Covalent bonds involve the sharing of electrons between nonmetal atoms. Lewis structures show these bonds as lines between atoms.

• Example: H2O has two covalent bonds between oxygen and hydrogen.

Bonding Patterns of Nonmetals

The number of bonds a nonmetal forms is determined by its group number.

• Example: Carbon (Group 14) forms 4 bonds; Nitrogen (Group 15) forms 3 bonds.

Alkanes: Naming and Drawing Hydrocarbons

Alkanes are saturated hydrocarbons with only single bonds.

• Methane: CH4

• Ethane: C2H6

• Propane: C3H8

• Up to Decane: C10H22

Alkenes and Alkynes: Naming and Drawing

Alkenes contain at least one double bond; alkynes contain at least one triple bond.

• Alkene Example: Ethene (C2H4), cis-trans isomerism possible.

• Alkyne Example: Ethyne (C2H2).

Cyclo Hydrocarbon Molecules

Cycloalkanes are ring-shaped hydrocarbons.

• Example: Cyclohexane (C6H12).

Isomers and Molecular Formulas

Isomers are compounds with the same molecular formula but different structures.

• Example: Butane and isobutane (C4H10).

Shapes and Bond Angles Around Carbon Atoms

• Single bond (tetrahedral): 109.5°

• Double bond (trigonal planar): 120°

• Triple bond (linear): 180°

Side Groups of Carbon Atoms

Common alkyl groups include methyl, ethyl, propyl, and isopropyl.

• Methyl: –CH3

• Ethyl: –CH2CH3

• Propyl: –CH2CH2CH3

• Isopropyl: –CH(CH3)2

Halogen Side Groups

Halogen atoms (F, Cl, Br, I) can be attached to hydrocarbons as substituents.

• Example: Chloromethane (CH3Cl)

Structural, Condensed, and Line Diagrams of Molecules

Organic molecules can be represented in several ways:

• Complete structural formula: Shows all atoms and bonds.

• Condensed structural formula: Groups atoms together (e.g., CH3CH2CH3).

• Line diagram: Lines represent carbon-carbon bonds; hydrogens are implied.