Chapter 6: The Periodic Table 6.1 Organizing the Elements

I. Early Organizing Principles A. Element properties used to sort them into groups B. First organized into triads, didn’t work with all Chlorine Iodine Bromine C. Mendeleev: organized based on increasing atomic mass, left empty spaces for unknown elements based on keeping common properties D. Later missing elements found

II. Modern Periodic Table A. Some elements violated Mendeleev’s order (Tellurium and Iodine) B. Modern table uses atomic number C. Rows are called “Periods” D. Periodic Law: if elements organized by increasing atomic number, there is periodic repetition of physical and chemical properties

III. Major Categories A. Metals: good conductors of heat and electricity, shiny, solid at room temp. (except Hg), ductile, malleable B. Non-metals: poor conductors (except Carbon), brittle solids, liquids, or gases C. Metalloids: similar properties to both metals and non-metals based on conditions

6.2 Classifying the Elements Sodium Silicon Argon

I. Groups (Columns) A. Alkali metals: very reactive metals with oxygen or water B. Alkali Earth metals: all have two outer electrons and tend to form +2 charged ions C. Transition metals: when compounds with them are dissolved in water, they form colored solutions

D. Inner Transition metals: many of these elements are man-made E. Halogens: very reactive non-metals F. Noble gases: very stable elements

II. E- Configurations in Groups A. Noble gases: have complete outer orbitals (ex. Ne) B. Representative elements: have incomplete S or P orbitals (ex. S) C. Transition metals: end on D-orbitals (ex. Fe) D. Inner transition metals: end on F-orbitals (ex. Ce)

6.3 PERIODIC TRENDS

I. Atomic Size A. One factor is # of electron orbitals B. Also based on charge of nucleus C. Increases down P.T., and from right to left Increasing atomic size Increasing atomic size

II. Ionic Size A. Cations (+ ions) smaller than their atoms since less electrons B. Anions (- ions) larger than atoms, more electrons C. Trend related to atomic size but not exactly same

III. Ionization Energy A. Energy required to remove electrons Increasing Ionization energy A. Energy required to remove electrons B. Every additional e- removed requires more energy C. Increases up P.T, from left to right Increasing ionization energy

IV. Why Remove Electrons? A. Atoms gain or lose e- to become more stable B. Full S and P orbitals (8 e-) more stable than partially filled ones C. Ex. Sodium will lose 1 e- and carry a 1+ charge, Fluorine will gain 1 e- and carry a 1- charge

V. Electronegativity A. Ability of atoms to attract electrons to itself B. Based on stability of elements C. Increases up P.T., and left to right Increasing electronegativity Increasing electronegativity