Early Atomic Models and Discoveries

Early Atomic Models & Discoveries

• John Dalton: proposed the atomic theory, which stated that elements are made up of atoms, atoms of the same element are identical, and atoms of different elements have different masses.
• J. J. Thomson: discovered electrons and proposed the plum pudding model, which suggested that atoms are positive spheres with negatively charged electrons embedded in them.
• Ernest Rutherford: discovered the nucleus of an atom through his gold foil experiment, which showed that positively charged alpha particles were deflected by a concentrated positive charge within the atom.
• James Chadwick: discovered neutrons, which are particles with no charge and a mass similar to protons, found in the nucleus of an atom.
• Niels Bohr: proposed the Bohr model, which stated that electrons occupy specific energy levels or orbits around the nucleus, and they do not radiate energy while in these orbits.

Periodic Table

• The periodic table arranges elements based on their atomic number and recurring chemical properties.
• It allows us to predict the properties of elements based on their position on the table.
• The periodic table is divided into groups (columns), periods (rows), and blocks.

Metals, Nonmetals, and Metalloids

• Metals: good conductors of heat and electricity, malleable (can be hammered into sheets), ductile (can be drawn into wires), and most are solids at room temperature.
• Nonmetals: poor conductors of heat and electricity, not malleable or ductile, and vary in state (gas, liquid, or solid) at room temperature.
• Metalloids: have properties between metals and nonmetals, often used as semiconductors.

Group Classifications

• Group 1 (Alkali Metals): highly reactive metals forming alkalis (strong bases) when reacting with water.
• Group 2 (Alkaline Earth Metals): reactive metals forming alkaline earths (oxides that form strong bases).
• Group 17 (Halogens): reactive nonmetals producing salts.
• Group 18 (Noble Gases): inert gases existing as single atoms.

Atomic Structure Terms

• Atomic Number: the number of protons in an atom, defining the element's chemical identity.
• Mass Number: the sum of protons and neutrons in the nucleus of an atom.
• Isotopes: atoms of the same element with different numbers of neutrons in their nuclei, leading to different mass numbers.
• Average Atomic Mass: the weighted average of the masses of all isotopes of an element, accounting for their natural abundance.

Ionic Compounds

• Ionic compounds are formed between a metal cation and a nonmetal anion.
• The charges of the cation and anion must balance to form an electrically neutral compound.

Nomenclature: Naming Compounds

• Ionic Compounds: name the cation followed by the anion, with the anion's name ending in "ide".
• Molecular Compounds: use prefixes to indicate the number of atoms of each element, followed by the name of the second element ending in "ide".
• Acids: binary acids start with "hydro" followed by the nonmetal's name ending in "ic acid".
• Oxyacids: named based on the oxyanion; "-ite" endings for oxyacids mean "-ous acid", while "-ate" endings mean "-ic acid".
• Bases: named by adding "hydroxide" to the cation's name.
• Hydrates: named with the compound's name followed by a prefix indicating the number of water molecules, ending in "hydrate."

Organic Chemistry

• Hydrocarbons: simplest organic compounds containing only carbon and hydrogen atoms.
• Aliphatic Hydrocarbons: form straight chains of carbon atoms.
• Alicyclic Hydrocarbons: form rings of carbon atoms.
• Aromatic Hydrocarbons: contain a benzene ring (C6H6), a special structure.

Naming Hydrocarbons

• The name is based on the length of the longest carbon chain (main chain).
• The end of the name indicates the type of bond: "-ane" for single bonds, "-ene" for double bonds, and "-yne" for triple bonds.
• Branch chains are named with the prefix "-yl" and their position on the main chain is indicated by a number.