Honors Chem - Semester One Study Guide

Significant Figures

Count sig figs: leading zeros never count; captive zeros always count; trailing zeros only count if decimal shown.

Multiplication and Division with Significant Figures

Result must have the same number of sig figs as the factor with the fewest sig figs.

Addition and Subtraction with Significant Figures

Result must have the same number of decimal places as the measurement with the fewest decimal places.

Dimensional Analysis

A method used for unit conversions.

Metric Prefixes

Includes kilo (k), centi (c), milli (m), and micro (µ).

Density Formula

Density = mass / volume.

Homogeneous Mixtures

Uniform composition throughout.

Heterogeneous Mixtures

Nonuniform composition.

Physical Changes

Include phase changes and dissolving.

Chemical Changes

Include color change, gas formation, precipitate, heat/light production.

States of Matter

Includes solid, liquid, gas, plasma. Different particle spacing and energy.

Dalton's Atomic Theory

A theory proposing that matter is composed of small indivisible particles called atoms.

Isotopes

Atoms with the same number of protons but different numbers of neutrons.

Atomic Emission Spectra

Specific wavelengths are emitted by electrons falling to lower energy levels.

Electromagnetic Radiation

Includes radio, microwave, infrared, visible, ultraviolet, X-ray, and gamma radiation.

Periodic Trends Across a Period

Atomic radius decreases, electronegativity increases, ionization energy increases.

Periodic Trends Down a Group

Atomic radius increases, electronegativity decreases, ionization energy decreases.

Periodic Groups

Includes alkali metals, alkaline earth metals, halogens, noble gases, transition metals.

Electron Orbitals

s=2, p=6, d=10, f=14 electrons.

Electron Configuration Example

For Chlorine (Cl): 1s² 2s² 2p⁶ 3s² 3p⁵.

Valence Electrons in Main Group Elements

Equal to the group number of the element.

Lewis Dot Diagrams

Represent valence electrons around the atomic symbol.

Ionic Compounds and Ions

Metals lose electrons (become + ions), nonmetals gain electrons (become - ions).

Writing Formulas for Ionic Compounds

Use criss-cross method for charges.

Naming Ionic Compounds

Combine metal name with nonmetal that ends in -ide; use Roman numerals for transition metals.

Molecular Compounds Composition

Composed of nonmetals; utilize prefixes for naming.

Naming Molecular Compounds

Prefix + nonmetal name; second component ends in -ide.

Electron Dot Formulas

Illustrate bonding and lone pairs in molecules.

Molecular Shapes (VSEPR)

Includes linear, bent, trigonal planar, trigonal pyramidal, and tetrahedral shapes.

Electronegativity and Bond Polarity

0–0.4 nonpolar, 0.5–1.7 polar, ≥2 ionic; molecular polarity depends on shape and symmetry.