Chemistry Chapter 2: Atoms, Molecules, and Ions

Flashcards covering key vocabulary, discoveries, and naming conventions from the Chemistry Chapter 2 lecture on Atoms, Molecules, and Ions.

Law of Conservation of Matter

States that the total mass of matter present remains constant when matter changes from one type to another during a chemical change, as atoms are neither created nor destroyed.

Law of Multiple Proportions

States that when two elements react to form more than one compound, a fixed mass of one element will react with masses of the other element in a ratio of small, whole numbers.

John Dalton

Proposed the atomic theory and the Law of Multiple Proportions, providing a microscopic explanation for macroscopic properties of matter.

J.J. Thomson

Experimented with cathode ray tubes and discovered the electron, determining its charge-to-mass ratio.

Cathode Ray Tubes

Experimental apparatus used by J.J. Thomson to discover the electron by observing the deflection of electron beams.

Robert A. Millikan

Conducted the Oil Drop Experiment in 1909, concluding that 1.602 x 10^-19 C was the charge of a single electron.

Plum Pudding Model

J.J. Thomson's early atomic model, suggesting atoms resembled a moist cake with embedded electron 'raisins' within a positive sphere.

Nagaoka Model

Proposed that atoms resembled the planet Saturn, with a ring of electrons surrounding a positive 'planet'.

Ernest Rutherford

Conducted the Gold Foil Scattering Experiment, leading to the discovery of the atomic nucleus.

Gold Foil Scattering Experiment

An experiment by Ernest Rutherford that involved aiming positively charged alpha particles at a thin piece of gold foil, revealing the existence of a small, dense, positively charged nucleus.

Alpha Particles

Positively charged particles used in Rutherford's Gold Foil Scattering Experiment to probe the structure of atoms.

Nucleus

A small, relatively heavy, positively charged body at the center of an atom that contains most of the atom's mass.

Proton

A positively charged subatomic particle located in the nucleus of an atom.

Isotopes

Atoms of the same element that differ in mass due to having the same number of protons but different numbers of neutrons.

Frederick Soddy

An English scientist credited with the discovery and naming of isotopes in the early 20th century.

Neutrons

Uncharged subatomic particles with a mass approximately the same as that of protons, also found in the nucleus.

James Chadwick

Discovered the neutron in 1932.

Atomic Number (Z)

The number of protons in the nucleus of an atom, which uniquely determines the identity of an element.

Mass Number (A)

The total number of protons and neutrons in an atom.

Neutral Atom

An atom that contains the same number of positive charges (protons) and negative charges (electrons), resulting in no net electrical charge.

Chemical Symbol

An abbreviation used to indicate an element or an atom of an element, typically one or two letters.

Protium

The most common isotope of hydrogen, having one proton and no neutrons (¹H).

Deuterium

An isotope of hydrogen with one proton and one neutron (²H or D).

Tritium

A radioactive isotope of hydrogen with one proton and two neutrons (³H or T).

Average Atomic Mass

The weighted average of the masses of an element's naturally occurring isotopes.

Ions

Electrically charged atoms or molecules where the number of protons and electrons are not equal.

Cation

An atom or molecule that has lost one or more electrons, resulting in a net positive charge.

Anion

An atom or molecule that has gained one or more electrons, resulting in a net negative charge.

Diatomic Elements

Elements that exist naturally as molecules composed of two atoms (e.g., H₂, N₂, O₂, F₂, Cl₂, Br₂, I₂).

Polyatomic Elements

Elements that exist naturally as molecules composed of more than two atoms (e.g., P₄, S₈).

Empirical Formula

Indicates the simplest whole-number ratio of the number of atoms (or ions) in a compound.

Molecular Formula

Indicates the actual numbers of atoms of each element in a molecule of the compound.

Dimitri Mendeleev

Widely credited with creating the first periodic table of the elements, arranging them by increasing atomic mass and predicting undiscovered elements.

Lothar Meyer

Independently recognized a periodic relationship among element properties around the same time as Mendeleev.

Eka-silicon

The name given by Mendeleev to a predicted element whose properties would be similar to silicon, later discovered as germanium.

Periodic Law (Mendeleev's)

The observation that when elements are arranged in order of increasing mass, certain sets of properties recur periodically.

Periodic Law (Modern)

States that the properties of the elements are periodic functions of their atomic numbers.

Periods (Series)

The horizontal rows of elements in the periodic table.

Groups

The vertical columns of elements in the periodic table, where elements have similar chemical properties.

Metals

Elements that are typically shiny, malleable, ductile, and good conductors of heat and electricity.

Nonmetals

Elements that typically appear dull, are often brittle, and are poor conductors of heat and electricity.

Metalloids

Elements that conduct heat and electricity moderately well and possess some properties of metals and some properties of nonmetals.

Main Group Elements (Representative Elements)

Elements in Groups 1, 2, and 13-18 of the periodic table.

Transition Metals

Elements located in Groups 3-12 (the 'B' section) of the periodic table.

Inner Transition Metals

The two rows of elements found at the bottom of the periodic table, including the Lanthanides and Actinides.

Lanthanides

The top row of inner transition metals.

Actinides

The bottom row of inner transition metals.

Chemical Bonds

Attractions between the charged particles (electrons and protons) that compose atoms, holding atoms together in compounds.

Ionic Bonds

Chemical bonds that occur between metals and nonmetals, involving the transfer of one or more electrons from the metal to the nonmetal.

Covalent Bonds

Chemical bonds that occur between two or more nonmetals, involving the sharing of electrons between atoms.

Ionic Compounds

Compounds held together by ionic bonds, typically formed between metals and nonmetals, and existing as an electrically neutral collection of ions.

Molecular Compounds

Compounds formed by covalent bonds between two or more nonmetals, existing as discrete, neutral molecules.

Formula Unit

The smallest, electrically neutral collection of ions in an ionic compound.

Monatomic Ions

Ions formed from only one atom.

Polyatomic Ions

Electrically charged molecules; a group of bonded atoms with an overall charge.

Oxyanions

Polyatomic ions that contain one or more oxygen atoms.

Nomenclature

A collection of rules for naming things, specifically chemical compounds in this context.

Binary Compounds

Compounds composed of only two different elements.

Type I Ionic Compounds

Ionic compounds containing a metal whose ion always has the same charge from one compound to another (e.g., Group 1, Group 2 metals).

Type II Ionic Compounds

Ionic compounds containing a metal that can form more than one kind of cation, where the charge of the metal ion must be specified using a Roman numeral in parentheses.

Hydrates

Ionic compounds containing a specific number of water molecules associated with each formula unit in their crystalline structure.

Hydrate Prefixes

Prefixes used in naming hydrates to indicate the number of water molecules (e.g., hemi- [0.5], mono- [1], di- [2], tri- [3], tetra- [4], penta- [5], hexa- [6], hepta- [7], octa- [8]).

Molecular Compound Naming

A system for naming compounds of two or more nonmetals using prefixes to indicate the number of atoms of each element (e.g., mono-, di-, tri-).

Prefixes for Molecular Compounds

Numerical prefixes used to indicate the number of atoms of each element in a molecular compound (mono- [1, often omitted for first element], di- [2], tri- [3], tetra- [4], penta- [5], hexa- [6], hepta- [7], octa- [8], nona- [9], deca- [10]).

Acids

Molecular compounds that release hydrogen ions (H⁺) when dissolved in water, often characterized by a sour taste and ability to dissolve many metals.

Aqueous (aq)

A state symbol indicating that a substance is dissolved in water.

Binary Acids

Acids that contain only two elements: hydrogen and one other nonmetal (e.g., HCl).

Oxyacids

Acids that contain hydrogen, oxygen, and one other nonmetal (e.g., H₂SO₄), formed with a polyatomic oxyanion.

Naming Binary Acids Rule

Prefix 'hydro-', followed by the base name of the nonmetal with an '-ic' ending, and then the word 'acid' (e.g., HCl becomes hydrochloric acid).

Naming Oxyacids Rule

If the polyatomic ion name ends in '-ate', change the ending to '-ic suffix' and add 'acid' (e.g., nitrate becomes nitric acid); if the ion ends in '-ite', change the ending to '-ous suffix' and add 'acid' (e.g., nitrite becomes nitrous acid).