2: Atoms and the Periodic Table
- Page ID
- 86194
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)- 2.1: Atomic Theory and the Structure of Atoms
- This page outlines John Dalton's modern atomic theory, which asserts that elements consist of atoms, the smallest units of matter. It emphasizes the uniqueness of atoms across different elements and the principle of conservation in chemical reactions. The page also introduces subatomic particles—protons, neutrons, and electrons—and their arrangement in atoms. These foundational concepts are essential to the study of chemistry.
- 2.2: Elements and Atomic Number
- This page covers atomic structure basics, emphasizing atomic and mass numbers. It defines atomic number (Z) as the number of protons, which identifies the element, while mass number (A) totals protons and neutrons. It also introduces isotopes, which share atomic numbers but differ in mass numbers. Exercises and examples help solidify understanding of these concepts across various elements.
- 2.3: Isotopes and Atomic Weight
- This page covers isotopes, which are element variations with different neutron counts but the same number of protons, affecting mass without altering chemical properties. It explains their representation and the concept of atomic weight as a weighted average based on isotopes' abundances. Examples include hydrogen and neon, alongside calculations for atomic masses of boron and magnesium.
- 2.4: The Periodic Table
- This page covers the arrangement and properties of elements in the periodic table, established by 19th-century scientists like Meyer and Mendeleev. It details the organization by atomic number and grouping based on similarities, categorizing elements as metals, nonmetals, or metalloids. It also discusses special categories, such as transition metals, emphasizing their importance in biological systems, especially the role of iron in hemoglobin.
- 2.5: Some Characteristics of Different Groups
- This page covers the periodic table's arrangement and its role in displaying trends in atomic properties like atomic radius and melting points. It notes that atomic radius decreases across periods and increases down groups, while melting points vary, generally being higher for metals than non-metals. Specific group characteristics are outlined for alkali metals, alkaline earth metals, halogens, and noble gases.
- 2.6: Electronic Structure of Atoms
- This page covers the arrangement of electrons in atoms, detailing the concepts of shells, subshells, and orbitals as dictated by quantum mechanics. It explains how electrons occupy energy levels represented by principal quantum numbers (n), with shells divided into subshells (s, p, d, f) containing various orbitals that define electron distribution and shape. This fundamental structure is crucial for understanding the chemical behavior of elements and the concept of electron configurations.
- 2.7: Electron Configurations
- This page covers electron configurations, detailing electron arrangement in atoms through principles like Aufbau, Hund's Rule, and Pauli-Exclusion. It explains the filling of energy levels, provides examples of configurations for the first 20 elements, and introduces noble gas shorthand notation. Visual representations, such as orbital diagrams, are included to illustrate these concepts, demonstrating how to construct configurations for various elements like sodium, phosphorus, and chlorine.
- 2.8: Electron Configurations and the Periodic Table
- This page explains the periodic table's organization by atomic number and electron configurations, detailing how elements are arranged into periods and groups corresponding to their electron subshells. It highlights that elements in the same column share similar valence configurations, leading to analogous chemical properties.
- 2.9: Electron-Dot Symbols
- This page explains the Lewis electron-dot symbol, illustrating how to represent an atom's valence electrons with dots around its symbol. Each dot represents a valence electron, with rules for pairing and placement, especially for 2s and 2p electrons. It highlights that an atomic symbol can have a maximum of eight surrounding dots. The page includes examples and exercises to support learning in creating these symbols.