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- https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Introductory_Chemistry_(CK-12)/04%3A_Atomic_Structure/4.06%3A_Dalton's_Atomic_TheoryThis page outlines the evolution of scientific thought on matter's composition, highlighting the debates preceding the 19th century. It emphasizes John Dalton's advancements in atomic theory, which po...This page outlines the evolution of scientific thought on matter's composition, highlighting the debates preceding the 19th century. It emphasizes John Dalton's advancements in atomic theory, which posited that matter is made of indivisible atoms and that atoms of the same element are identical. Dalton's 1804 theory established foundational principles for modern chemistry, although some aspects, like atomic indivisibility, have been updated.
- https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Introductory_Chemistry_(CK-12)/04%3A_Atomic_Structure/4.16%3A_Atomic_NumberThis page explores individuality through identifiers such as cell phone numbers and DNA, then shifts to atomic theory, explaining how atomic numbers define elements based on proton counts. It emphasiz...This page explores individuality through identifiers such as cell phone numbers and DNA, then shifts to atomic theory, explaining how atomic numbers define elements based on proton counts. It emphasizes the organization of the periodic table for predicting element properties and notes that atoms are neutral, with equal numbers of protons and electrons, underscoring the foundational aspect of atomic structure.
- https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Introductory_Chemistry_(CK-12)/05%3A_Electrons_in_Atoms/5.19%3A_Valence_ElectronsThis page explains valence electrons as the outermost electrons in an atom's highest energy level, which determine reactivity. It highlights that elements react differently based on their valence elec...This page explains valence electrons as the outermost electrons in an atom's highest energy level, which determine reactivity. It highlights that elements react differently based on their valence electron count, with lithium having one, beryllium two, and boron three. As one progresses across a period, valence electrons increase, reaching eight in neon. The summary also distinguishes between valence and inner shell electrons, noting that only valence electrons affect reactivity.
- https://chem.libretexts.org/Courses/Prince_Georges_Community_College/CHEM_2000%3A_Chemistry_for_Engineers_(Sinex)/Unit_1%3A_Atomic_Structure/Chapter_1%3A_Introduction/Chapter_1.2%3A_Isotopes_and_Atomic_MassesThe isotopes of an element differ only in their atomic mass, which is given by the mass number (A)The number of protons and neutrons in the nucleus of an atom of an element., the sum of the numbers of...The isotopes of an element differ only in their atomic mass, which is given by the mass number (A)The number of protons and neutrons in the nucleus of an atom of an element., the sum of the numbers of protons and neutrons. Although the masses of the electron, the proton, and the neutron are known to a high degree of precision (Table 1.2.2), the mass of any given atom is not simply the sum of the masses of its electrons, protons, and neutrons.
- https://chem.libretexts.org/Courses/Westminster_College/CHE_180_-_Inorganic_Chemistry/13%3A_Chapter_13_-_s-Block_Elements/13.1%3A_Properties_of_Group_1_MetalsThis page discusses the trends in some atomic and physical properties of the Group 1 elements - lithium, sodium, potassium, rubidium and cesium. Sections below cover the trends in atomic radius, first...This page discusses the trends in some atomic and physical properties of the Group 1 elements - lithium, sodium, potassium, rubidium and cesium. Sections below cover the trends in atomic radius, first ionization energy, electronegativity, melting and boiling points, and density.
- https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Introductory_Chemistry_(CK-12)/02%3A_Matter_and_Change/2.02%3A_Pure_SubstancesThis page defines substances in chemistry as pure materials with uniform compositions that can't be separated. It provides examples like silver and acetylsalicylic acid, noting that aspirin is a mixtu...This page defines substances in chemistry as pure materials with uniform compositions that can't be separated. It provides examples like silver and acetylsalicylic acid, noting that aspirin is a mixture. Substances may exist in solid, liquid, or gas forms based on temperature, and the text emphasizes the necessity of using pure substances in chemical reactions for reliable outcomes.
- https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Introductory_Chemistry_(CK-12)/17%3A_Thermochemistry/17.16%3A_Standard_Heat_of_FormationThis page discusses the Hope diamond, valued at $350 million, and compares it to graphite, which is much cheaper. It explains that the differences between these two forms of carbon arise from their di...This page discusses the Hope diamond, valued at $350 million, and compares it to graphite, which is much cheaper. It explains that the differences between these two forms of carbon arise from their distinct organizational structures and formation conditions. It also defines standard heat of formation (ΔHof), describing it as the enthalpy change involved in forming a mole of a compound from its elements at specified standard conditions.
- https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Introductory_Chemistry_(CK-12)/02%3A_Matter_and_Change/2.15%3A_Chemical_Symbols_and_FormulasThis page highlights how chess players use specialized symbols for game documentation, similar to how chemists use chemical symbols for elements and compounds. Chemical symbols, typically made up of o...This page highlights how chess players use specialized symbols for game documentation, similar to how chemists use chemical symbols for elements and compounds. Chemical symbols, typically made up of one or two letters, often derive from English or Latin, while chemical formulas represent the composition and proportions of elements in compounds (e.g., H₂O for water). Grasping these symbols is essential for success in both chess and chemistry.
- https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Introductory_Chemistry_(CK-12)/02%3A_Matter_and_Change/2.14%3A_Chemical_ChangeThis page explains how cooking involves chemical changes that transform basic ingredients into new substances, exemplified by bread from flour, sugar, yeast, and water. These changes occur when elemen...This page explains how cooking involves chemical changes that transform basic ingredients into new substances, exemplified by bread from flour, sugar, yeast, and water. These changes occur when elements combine or compounds break down, leading to the creation of materials used in food, fabrics, medicine, and safety devices. Recognizing these transformations underscores chemistry's relevance in everyday life.
- https://chem.libretexts.org/Bookshelves/General_Chemistry/General_Chemistry_Supplement_(Eames)/Chemistry_Basics/IntroductionHe finds it more suitable to mount Pegasus (obviously loaned from the Veterinary School) and to proclaim ... how, during his flight to the top of the chemical Parnassus, the atoms appeared to be arran...He finds it more suitable to mount Pegasus (obviously loaned from the Veterinary School) and to proclaim ... how, during his flight to the top of the chemical Parnassus, the atoms appeared to be arranged in the universe." (In ancient Greek mythology, Pegasus is a horse with wings, and Parnassus is a mountain associated with art and knowledge because the Muses were said to live there.)
- https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Introductory_Chemistry_(CK-12)/07%3A_Chemical_NomenclatureThis page discusses the role of the International Union of Pure and Applied Chemistry (IUPAC) in standardizing chemical nomenclature, including molecular and empirical formulas. It covers cations, ani...This page discusses the role of the International Union of Pure and Applied Chemistry (IUPAC) in standardizing chemical nomenclature, including molecular and empirical formulas. It covers cations, anions, transition metal ions, and the naming conventions for binary and ternary ionic compounds, molecular compounds, acids, and bases, stressing the importance of accurate nomenclature in chemistry and biology.
