ch2 chem

Law of Conservation of Mass

Antoine Lavoisier-Mass is neither created nor destroyed in a chemical reaction; total mass of reactants = total mass of products.

Law of Definite Proportions

Joseph Louis Proust-A given compound always contains the same proportion of elements by mass.

Dalton’s Atomic Theory

1. Elements are made of atoms. 2. Atoms of the same element are identical. 3. Atoms of different elements differ. 4. Compounds = atoms of different elements combined in fixed ratios. 5. Chemical reactions rearrange atoms.

J.J. Thomson’s experiment

Showed the existence of electrons and introduced the Plum Pudding Model.

Rutherford’s experiment

Discovered the nucleus and showed that atoms are mostly empty space.

Millikan’s experiment

Measured the charge of the electron and calculated its mass.

Becquerel's discovery

Discovered radioactivity in uranium; atoms emit radiation spontaneously.

Subatomic particles

Protons (+1, mass ~1 amu, nucleus), Neutrons (0, mass ~1 amu, nucleus), Electrons (-1, mass ~0 amu, orbit nucleus).

Isotope

Atoms of the same element with different numbers of neutrons, same chemical behavior but different mass.

Periodic table groups

Group = vertical column (similar properties); Period = horizontal row (same electron shells).

Periodic table organization

Elements are organized by increasing atomic number.

Main element families

Alkali metals (1A), alkaline earth metals (2A), halogens (7A), noble gases (8A).

Covalent bond

A bond formed by the sharing of electrons between nonmetals.

Ionic bond

A bond formed by the transfer of electrons from metal to nonmetal.

Formation of cations

Metals lose electrons to form positively charged ions.

Formation of anions

Nonmetals gain electrons to form negatively charged ions.

Cation

A positive ion that has lost one or more electrons.

Anion

A negative ion that has gained one or more electrons.

Polyatomic ion

A group of atoms bonded together with an overall charge.

Naming Type I binary ionic compounds

Cation keeps its name, anion changes to root + '-ide.' Example: NaCl = sodium chloride.

Naming Type II binary ionic compounds

Use Roman numerals for metals with variable charges. Example: FeCl₂ = iron(II) chloride.

Naming binary covalent compounds (Type III)

Use prefixes; first element keeps full name, second = root + '-ide.' Example: CO₂ = carbon dioxide.

Naming acids without oxygen

Use 'Hydro' + root of anion + 'ic acid.' Example: HCl = hydrochloric acid.

Naming acids with oxygen

Change '-ate' to '-ic acid' and '-ite' to '-ous acid.' Example: HNO₃ = nitric acid.