Chapter 5 Vocabulary Actinides- the 14 elements with atomic numbers from 90 (thorium, Th) to 103 (lawrencium, Lr) Alkali metals- the elements of Group 1 of the Periodic Table (Li, Na, K, rubidium, cesium, and francium) Alkaline earth-metals- the elements of Group 2 of the Periodic Table (beryllium, Mg, Ca, strontium, barium, and radium) Anion- a negative ion Atomic radius- one-half the distance between the nuclei of identical atoms joined in a molecule Cation- a positive ion Electron affinity- the energy change that occurs when an electron is acquired by a neutral atom Electronegativity- a measure of the ability of an atom in a chemical compound to attract electrons Halogens- the elements of Group 17 (Fluorine, Chlorine, bromine, iodine, and astatine) Ion- an atom or group of atoms that has a positive or negative charge Ionization energy- the energy required to remove one electron from an atom of an element (first ionization energy) Lanthanides, or rare-earth elements- the 14 elements with atomic numbers from 58 (cerium, Ce) to 71 (lutetium, Lu) Main-group elements- the p-block elements together with the s-block elements Periodic law- the physical and chemical properties of the elements are periodic functions of their atomic numbers Periodic Table- an arrangement of the elements in order of their atomic numbers so that elements with similar properties fall in the same column Transition elements- the d-block elements are all metals with typical metallic properties Valence electrons- electrons available to be lost, gained, or shared in the formation of chemical compound

Chapter 5 Cheat Sheet

The Concept of Periodicity o First Congrees of Chemist -1851 (a method for determining the relative atomic mass of the elements is proposed by Cannizzaro) o Mendeleev’s ordering of elements by known properties and atomic mass – the first periodic table (1869) o Rapid discovery of missing elements in Mendeleev’s table confirm predictions of atomic mass and chemical properties. o The discrepancy in the atomic mass of nitrogen leads to the discovery of Argon, Helium, and other noble gases Lord Raleigh and William Ramsey) o Moseley, 1911, proposes the concept of the atomic number based on the number ofprotons in an atoms nucleus. The periodic order recognized as consistent with increasing atomic number rather than atomic mass. • Counting Atoms o Elemental isotopes – fixed number of protons associate with different number of protons associate with different numbers of neutrons (e.g., protium, deuterium, tritium).  Mass number (sum of protons and neutrons)  Designating isotopes o Relative atomic mass (based on carbon – 12 ((6 protons, 6 neutrons))) o Average atomic mass and isotomic abundance o The mole – a relationship between average atomic mass and the number of atoms  Avogadro’s number (6.022 x 1023 atoms/moe)  Molar mass  1 mole = combining masses x # that appears in #) • Periods and Blocks of the Periodic Table (the periodic table was proposed based on the known properties of the elements nearly 70 yrs. before the modern atom was conceived. ) o Relationship between period length and the highest principal quantum number (outer shell). (Making sense of the inertness of the Noble gases.)  1s2 = period length of 2 for 1st period  2s22p6 = period length of 8 for 2nd period  3s23p6 = period length of 8 for 3rd period  4s2ed1046 = period length of 18 for 4th period  5s24d105p6 = period length of 18 for 5th period  6s25d104f146p6 = period length of 32 for 6th period  7s26d105f147p6 = period length of 32 for 7th period (only the first six are naturally occurring elements) o Blocks and the angular momentum quantum number (orbitals) – highest energy orbitals occupied.  s-block elements: Groups 1&2  P-block elements: Groups 13 to 18  d-block elements: Groups 3 to 12  f-block elements: Lanthanides and Actinides o Some special groups within the Blocks  Group 1: Alkali metals (s-block with one electron) plus Hydrogen  Group 2: Alkaline Earth metals (s-block with two electrons)  Transition metals (d-block and f-block)  Other metals (p-block with 1 to 4 electrons beginning at the 3rd period)  Metalloids (p-block with one or two electrons beginning at the 2nd period)  Group 17: Halogens (p-block with 7 electrons)  Other non-metals (p-block with 2 to 6 electrons beginning at the 2nd period)  Group 18: Noble gases (s-block with 2 [He], and p-block with 8) • Electron Configuration and Periodic Properties ( Properties of concern are those derived from the physical states of the elements, their combinations with other elements, and the ease with which they can be made to react.) o Atomic radii (atoms are conceived of as having spherical geometry)  Means of estimation  Effects of increasing nuclear charge and orbital electron density  Noble gas – force it to become liquid o Ionization Energy: A + energy becomes A+ + e (the least energy that must be added to an electron to remove it from the attraction of the nucleus.)  Valence electrons – group trends  Periodic trends  Adding electrons to negative ions o Electron Affinity: A + e- becomes A- + e- (The least energy that must be added to an electron to remove it from the attraction of the nucleus)  Period trends  Group trends  Adding electrons to negative ion o Ionic radii: cations and anions  Period trends  Group trends o Valence electrons: electrons available to be lost, gained, or shared in the formation of chemical compounds. o Electronegativity: a measure of the relative ability of an atom in a chemical compound to attract electrons.  Table wide trends  Period trends  Group trends o Periodic properties of the d- and f-Block elements  Atomic radii  Ionization energy  Ion formation and ionic radii  Electronegativity