Skip to main content
Chemistry LibreTexts

2: Elements, Atoms, and the Periodic Table

  1. Last updated
  2. Save as PDF
  • Page ID
    15921
    • Anonymous
    • LibreTexts

    \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)

    \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)

    \( \newcommand{\dsum}{\displaystyle\sum\limits} \)

    \( \newcommand{\dint}{\displaystyle\int\limits} \)

    \( \newcommand{\dlim}{\displaystyle\lim\limits} \)

    \( \newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\)

    ( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\)

    \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)

    \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\)

    \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)

    \( \newcommand{\Span}{\mathrm{span}}\)

    \( \newcommand{\id}{\mathrm{id}}\)

    \( \newcommand{\Span}{\mathrm{span}}\)

    \( \newcommand{\kernel}{\mathrm{null}\,}\)

    \( \newcommand{\range}{\mathrm{range}\,}\)

    \( \newcommand{\RealPart}{\mathrm{Re}}\)

    \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)

    \( \newcommand{\Argument}{\mathrm{Arg}}\)

    \( \newcommand{\norm}[1]{\| #1 \|}\)

    \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)

    \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\AA}{\unicode[.8,0]{x212B}}\)

    \( \newcommand{\vectorA}[1]{\vec{#1}}      % arrow\)

    \( \newcommand{\vectorAt}[1]{\vec{\text{#1}}}      % arrow\)

    \( \newcommand{\vectorB}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)

    \( \newcommand{\vectorC}[1]{\textbf{#1}} \)

    \( \newcommand{\vectorD}[1]{\overrightarrow{#1}} \)

    \( \newcommand{\vectorDt}[1]{\overrightarrow{\text{#1}}} \)

    \( \newcommand{\vectE}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{\mathbf {#1}}}} \)

    \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)

    \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)

    \(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)

    Just as a language has an alphabet from which words are built, chemistry has an alphabet from which matter is described. However, the chemical alphabet is larger than the one we use for spelling. You may have already figured out that the chemical alphabet consists of the chemical elements. Their role is central to chemistry, for they combine to form the millions and millions of known compounds.

    • 2.0: Prelude to Elements, Atoms, and the Periodic Table
      This page discusses the importance of tooth enamel, its vulnerability to decay, and the discovery of fluorine’s protective effects against dental decay. In the early 1900s, brown-stained teeth in Colorado Springs were linked to fluorine in water, leading to findings that low levels of fluorine could strengthen enamel without discoloration.
    • 2.1: The Elements
      This page explains that a chemical element is a basic substance that cannot be divided further, with 118 recognized elements, 90 naturally occurring. Hydrogen and helium are the most abundant in the universe, while oxygen and silicon prevail in Earth's crust. The page covers chemical symbols, their etymology, and exercises to identify elements and symbols.
    • 2.2: Atomic Theory
      This page explains the essential ideas of modern atomic theory, initiated by John Dalton in 1803, which posits that matter is made up of atoms. It differentiates between single atoms and diatomic molecules like H2 and O2, and stresses the significance of molecular formulas. Furthermore, it presents a historical overview, connecting the theory to the ideas of ancient Greek philosophers while underscoring its scientific foundations.
    • 2.3: The Structure of Atoms
      This page explains the structure of atoms, which are composed of protons, neutrons, and electrons. Protons and neutrons are found in the nucleus, while electrons orbit around it. The planetary model by Rutherford shows that most mass is in the nucleus, although modern interpretations view electrons as existing in fuzzy clouds rather than fixed paths. It also notes that protons and neutrons have similar and much larger mass compared to electrons.
    • 2.4: Nuclei of Atoms
      This page discusses atomic composition, emphasizing atomic numbers, mass numbers, and isotopes. The atomic number identifies elements by the number of protons, while isotopes vary in neutron count affecting mass. It details calculations for specific isotopes and explains the importance of distinguishing isotopes in scientific contexts.
    • 2.5: Atomic Masses
      This page explains atomic mass and atomic mass units (amu), stating that 1 amu is 1/12 of the mass of a carbon-12 atom. It describes atomic mass as the weighted average of an element's isotopes, taking into account their natural abundances. The text emphasizes that an atom's mass is mainly influenced by its protons and neutrons, and that the atomic mass shown in the Periodic Table reflects the average mass of all isotopes of the element, providing examples for clarity.
    • 2.6: Arrangements of Electrons
      This page explains electron organization within atoms based on quantum mechanics, detailing shells and subshells defined by energy levels and quantum numbers. It covers electron configurations for various elements, the systematic filling order related to atomic numbers, and the significance of valence and core electrons in chemical reactivity.
    • 2.7: The Periodic Table
      This page explains the periodic table's organization by atomic number and properties, with elements grouped by similarities. Developed by Mendeleev, it identifies metals, nonmetals, and semimetals, highlighting trends in atomic radii and special categories like halogens and noble gases. It discusses specific elements, such as fluorine and radon, and introduces clinical chemistry, which analyzes body fluids to assess health and correlates element placement with valence electron numbers.
    • 2.E: Elements, Atoms, and the Periodic Table (Exercises)
      These are homework exercises to accompany Chapter 2 of the Ball et al. "The Basics of GOB Chemistry" Textmap.
    • 2.S: Elements, Atoms, and the Periodic Table (Summary)
      This page explains atomic structure and the periodic table, defining elements and detailing atoms as their smallest units made of protons, neutrons, and electrons. It covers concepts like atomic number, isotopes, and mass number, alongside electron behavior and configuration based on quantum mechanics. The text highlights the periodic table's role in organizing elements by properties and trends, including atomic radius.

    Thumbnail: Ionization energies superimposed on a periodic table. (CC BY-NC-SA; anonymous by request).

    This page titled 2: Elements, Atoms, and the Periodic Table is shared under a CC BY-NC-SA 3.0 license and was authored, remixed, and/or curated by Anonymous via source content that was edited to the style and standards of the LibreTexts platform.