Atoms, Molecules, and Ions

Vocabulary flashcards covering atomic structure, subatomic particles, isotopes, periodic table groups, ionic/molecular formulas, chemical nomenclature, oxoacids, bases, and hydrates from Chapter 2.

Dalton's Atomic Theory (1808)

The atomic theory proposed in $1808$ stating that elements consist of indivisible small particles called atoms, all atoms of a given element are identical, compounds form from fixed whole-number or fractional ratios of different atoms, and chemical reactions involve atomic rearrangement without creation or destruction.

Atom

The extremely small particle that composes elements, consisting of a central nucleus surrounded by dispersed electrons.

Nucleus

The tiny, dense, positively charged core of an atom that contains protons and neutrons and accounts for more than $99GS_PERCENT$ of the atom's total mass.

Proton

A positively charged subatomic particle found in the nucleus with a charge unit of $+1$ ($+1.6022 \times 10^{-19GS_COULOMB}$) and a mass of approximately $1.0073GS_AMU$ ($1.67262 \times 10^{-24GS_GRAMS}$).

Neutron

An electrically neutral subatomic particle located in the nucleus with a charge unit of $0$ and a mass of approximately $1.0087GS_AMU$ ($1.67493 \times 10^{-24GS_GRAMS}$).

Electron

An extremely lightweight subatomic particle dispersed around the nucleus with a charge unit of $-1$ ($-1.6022 \times 10^{-19GS_COULOMB}$) and a mass of approximately $5.486 \times 10^{-4GS_AMU}$ ($9.10938 \times 10^{-28GS_GRAMS}$).

Atomic Mass Unit (amu)

A unit of mass defined as $1GS_AMU = 1.6605 \times 10^{-24GS_GRAMS}$.

Atomic Number (Z)

The total number of protons present in the nucleus of each atom of a given element.

Mass Number (A)

The total number of protons and neutrons present in the nucleus of an atom.

Isotopes

Atoms of the same element that have the same atomic number (number of protons) but different mass numbers due to differing numbers of neutrons in their nuclei.

Metals

Elements that possess a characteristic luster, are good conductors of heat and electricity, tend to lose electrons, and are solids at room temperature (with the exception of mercury).

Nonmetals

Elements that lack metallic properties, are poor conductors of heat and electricity, tend to accept electrons, and exist as gases, brittle solids, or liquid (bromine) at room temperature.

Metalloids

Elements situated along the stair-step line on the periodic table that exhibit properties intermediate between those of metals and nonmetals.

Alkali Metals

The reactive metallic elements found in Group 1A (Group 1) of the periodic table, including lithium, sodium, potassium, rubidium, cesium, and francium.

Alkaline Earth Metals

The metallic elements found in Group 2A (Group 2) of the periodic table, including beryllium, magnesium, calcium, strontium, barium, and radium.

Halogens

The nonmetallic elements located in Group 7A (Group 17) of the periodic table, including fluorine, chlorine, bromine, iodine, and astatine.

Chalcogens

The elements belonging to Group 6A (Group 16) of the periodic table, including oxygen, sulfur, selenium, tellurium, and polonium.

Noble Gases

The unreactive gas elements located in Group 8A (Group 18) of the periodic table, also referred to as rare gases.

Transition Metals

Elements located in Groups 3B to 2B (Groups 3 to 12) of the periodic table that can form cations with varying positive charges.

Molecule

An aggregate of at least two atoms in a definite arrangement held together by chemical bonds.

Diatomic Molecule

A molecule that consists of exactly two atoms bonded together, such as $\text{H}_2$.

Polyatomic Molecule

A molecule that contains more than two atoms bonded together, such as $\text{H}_2\text{O}$, $\text{NH}_3$, or $\text{CH}_4$.

Ion

An atom or group of atoms that carries a net positive or negative electric charge.

Cation

A positively charged ion formed when a neutral atom loses one or more electrons.

Anion

A negatively charged ion formed when a neutral atom gains one or more electrons.

Monatomic Ion

An ion that consists of only a single atom carrying a net charge, such as $\text{Na}^+$ or $\text{Cl}^-$.

Polyatomic Ion

A charged chemical species composed of two or more atoms covalently bonded together, such as $\text{OH}^-$ or $\text{NH}_4^+$.

Molecular Formula

A chemical formula that indicates the exact number of atoms of each element in the smallest unit of a substance.

Empirical Formula

A chemical formula that expresses the simplest whole-number ratio of the atoms present in a substance.

Structural Formula

A chemical representation showing the arrangement and bonding pattern of atoms within a molecule.

Ionic Compound

A compound composed of cations and anions held together by electrostatic attraction, where the total positive charge equals the total negative charge.

Binary Compound

A chemical compound formed from exactly two different elements.

Oxoacid

An acid that contains hydrogen, oxygen, and another central element.

Oxoanion

An anion produced upon the removal of all $\text{H}^+$ ions from an oxoacid.

Base

A substance that yields hydroxide ions ($\text{OH}^-$) when dissolved in water.

Hydrate

A compound that has a specific number of water molecules attached to its formula unit.

Rutherford's Gold Foil Experiment

An experiment using an alpha-particle emitter directed at thin gold foil with a detecting screen, demonstrating that positive charge and mass are concentrated in a dense central nucleus.

Oxoanion Naming Scheme

A systematic nomenclature rule for polyatomic oxoanions based on oxygen count: 'per- + root + -ate' (most O), 'root + -ate' (more O), 'root + -ite' (less O), and 'hypo- + root + -ite' (least O).

Chemical Compound Classification Flowchart

A decision tree categorizing chemical compounds as ionic or molecular to apply appropriate naming rules and Roman numeral or prefix conventions.