The Structure of the Atom

Atoms, Molecules, and Ions > The Structure of the Atom The Structure of the Atom • Overview of Atomic Structure • Atomic Number and Mass Number • Isotopes Free to share, print, make copies and changes. Get yours at www.boundless.com www.boundless.com/chemistry

Atoms, Molecules, and Ions Structure of an Atom Elements, such as helium, depicted here, are made up of atoms.Atoms are made up of protons and neutrons located within the nucleus, with electrons in orbitals surrounding the nucleus. Free to share, print, make copies and changes. Get yours at www.boundless.com Connexions. "Print ." CC BY 3.0http://cnx.org/content/m44390/latest/Figure_02_01_01.jpgView on Boundless.com

Atoms, Molecules, and Ions Protons, Neutrons, and Electrons Both protons and neutrons have a mass of 1 amu and are found in the nucleus.However, protons have a charge of +1, and neutrons are uncharged.Electrons have a mass of 0 amu, orbit the nucleus, and have a charge of -1. Free to share, print, make copies and changes. Get yours at www.boundless.com Connexions. "Atoms, Isotopes, Ions, and Molecules: The Building Blocks." CC BY 3.0http://cnx.org/content/m44390/latest/?collection=col11448/latestView on Boundless.com

Atoms, Molecules, and Ions > The Structure of the Atom Overview of Atomic Structure • An atom is composed of two regions: the nucleus, which is in the center of the atom and contains protons and neutrons, and the outer region of the atom which holds its electrons in orbit around the nucleus. • Protons and neutrons have approximately the same mass, about 1.67 × 10-24 grams, which scientists define as one atomic mass unit (amu) or one Dalton. • Each electron has a negative charge equal to the positive charge of a proton. • Neutrons are uncharged particles found within the nucleus. Structure of an Atom View on Boundless.com Free to share, print, make copies and changes. Get yours at www.boundless.com www.boundless.com/chemistry/atoms-molecules-and-ions/the-structure-of-the-atom/overview-of-atomic-structure

Atoms, Molecules, and Ions > The Structure of the Atom Isotopes • Despite having different numbers of neutrons, isotopes of the same element have very similar physical properties. • Some isotopes are unstable and will undergo radioactive decay to become other elements. • The predictable half-life of different decaying isotopes allows scientists to date material based on its isotopic composition, such as with Carbon-14 dating. Application of carbon dating View on Boundless.com Free to share, print, make copies and changes. Get yours at www.boundless.com www.boundless.com/chemistry/atoms-molecules-and-ions/the-structure-of-the-atom/isotopes

Atoms, Molecules, and Ions Atomic number, Chemical Symbol, and Mass Number Carbon has an atomic number of six, and two stable isotopes with mass numbers of twelve and thirteen, respectively.Its atomic mass is 12.11. Free to share, print, make copies and changes. Get yours at www.boundless.com Connexions. "Atoms, Isotopes, Ions, and Molecules: The Building Blocks." CC BY 3.0http://cnx.org/content/m44390/latest/?collection=col11448/latestView on Boundless.com

Atoms, Molecules, and Ions Free to share, print, make copies and changes. Get yours at www.boundless.com

Atoms, Molecules, and Ions Free to share, print, make copies and changes. Get yours at www.boundless.com Boundless - LO. "Boundless." CC BY-SA 3.0http://www.boundless.com/

Atoms, Molecules, and Ions Free to share, print, make copies and changes. Get yours at www.boundless.com Boundless - LO."Boundless." CC BY-SA 3.0http://www.boundless.com/

Atoms, Molecules, and Ions Key terms • atomthe smallest possible amount of matter which still retains its identity as a chemical element, consisting of a nucleus surrounded by electrons (CC BY-SA 3.0) • atomic massthe quantity of matter in an atomic particle, sub-atomic particle, or molecule (CC BY-SA 3.0) • atomic numberThe number of protons in an atom. (CC BY-SA 3.0) • electronThe subatomic particle having a negative charge and orbiting the nucleus; the flow of electrons in a conductor constitutes electricity. (CC BY-SA 3.0) • isotopeany of two or more forms of an element where the atoms have the same number of protons, but a different number of neutrons within their nuclei (CC BY-SA 3.0) • neutronA subatomic particle forming part of the nucleus of an atom and having no charge.It is equal in mass to a proton. (CC BY-SA 3.0) • protonPositively charged subatomic particle forming part of the nucleus of an atom and determining the atomic number of an element. (CC BY-SA 3.0) Free to share, print, make copies and changes. Get yours at www.boundless.com

Atoms, Molecules, and Ions Attribution • Connexions. "Fundamental force types." CC BY 3.0http://cnx.org/content/m14044/latest/ • Connexions. "Atoms, Isotopes, Ions, and Molecules: The Building Blocks." CC BY 3.0http://cnx.org/content/m44390/latest/?collection=col11448/latest • Connexions. "Atoms, Isotopes, Ions, and Molecules: The Building Blocks." CC BY 3.0http://cnx.org/content/m44390/latest/?collection=col11448/latest • Wikibooks. "A-level Chemistry/OCR/Atoms, Bonds and Groups/Atoms and Reactions/Atoms." CC BY-SA 3.0http://en.wikibooks.org/wiki/A-level_Chemistry/OCR/Atoms,_Bonds_and_Groups/Atoms_and_Reactions/Atoms • Connexions. "Atoms, Isotopes, Ions, and Molecules: The Building Blocks." CC BY 3.0http://cnx.org/content/m44390/latest/?collection=col11448/latest • Wikipedia. "Radiocarbon dating." CC BY-SA 3.0http://en.wikipedia.org/wiki/Radiocarbon_dating Free to share, print, make copies and changes. Get yours at www.boundless.com

The Structure of the Atom