Mrs. Page IB SL Chemistry 2015-2016 • The periodic table is arranged into four blocks associated with the four sub-levels – s, p, d, and f. • The periodic table consists of groups (vertical columns) and periods (horizontal rows). • The period number (n) is the outer energy level that is occupied y electrons. • The number of the principal energy level and the number of the valence electrons in an atom can be deduced from its position on the periodic table. • The periodic table shows the position of metals, non- metals and metalloids. • Deduction of the electron configuration of an atom from the element's position on the periodic table and vice versa. NOS • Obtain evidence for scientific theories by making and testing predictions based on them – scientists organize subjects based on structure and function; the periodic table is a key example of this. Early models of the periodic table from Mendeleev, and later Moseley, allowed for the prediction of properties of elements that had not yet been discovered. Dobereiner (1817): Law of triads • Certain groups of three elements shared similar chemical and physical properties (Ca, Sr, Ba; Cl, Br, I; Li, Na, K) • The middle element in a triad had an atomic mass close to the average of the relative atomic masses of the other two elements • This was the first link between atomic mass and properties of the elements Newlands (1864): Law of Octaves • Arranged elements by relative atomic mass. • 7 elements per row • Appeared to be a repeating pattern every 8th element • Not widely accepted – Fe ended in same group as O and S (non-metals)

http://www.bbc.co.uk/schools/gcsebitesize/science/edexcel_pre_2011/patterns/periodictablerev3.shtml Mendeleev (1869): The Periodic Law • Arranged atoms by relative atomic mass but also used the physical and chemical properties to arrange elements into vertical columns • Left gaps for undiscovered elements • Some elements didn’t follow pattern – I has lower mass than Te

http://www.bbc.co.uk/schools/gcsebitesize/science/edexcel_pre_2011/patterns/periodictablerev4.shtml Moseley(1913): The Modern Periodic Law • Arranged elements by increasing atomic number (Z) • Basis for the current day periodic table • Groups: vertical columns (1-18) • Have similar properties due to the same number of valence electrons • IUPAC names of Groups: • Group 1: alkali metals • Group 2: alkaline earth metals • Groups 3-12: transition metals (not IUPAC) • Group 15: pnictogens • Group 16: chalcogens • Group 17: halogens • Group 18: noble gases • Periods: horizontal rows (1-7) • Period number = principal quantum number, n, of the highest occupied energy level of the elements in that period • Example: Write the electron configuration for Br • 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5 • Bromine is in period 4 and has 4 energy levels n = 1, 2, 3, and 4 commons.wikimedia.org • Good conductors (heat & electricity) • Malleable (can be hammered into sheets) • Ductile (can be pulled into wire) • Have Luster (shiny) • Usually lose electrons (getting oxidized) • All solid at room temp. except Hg • Hg dissolves other metals forming a solution called an amalgam – used as fillings for dental work in the past • Poor conductors (heat & electricity) • Dull in appearance • If solid, often brittle (snap into pieces) • Usually gain electrons (getting reduced) • Many are gases at room temperature but not all

• 7 diatomic gases (H2, N2, O2, F2, Cl2, Br2, I2) • Have both metallic and non-metallic properties • Include B, Si, Ge, As, Sb, Te, and At • Si & Ge – semiconductors used in electronics The properties of the main group elements is often predictable, however the transition elements are less predictable. The number of valence electrons is found from the group number of the s and p block elements! Consider the element Tungsten Z=74 a) state the number of protons, neutrons and electrons an atom of tungsten b) To what group of the periodic table does tungsten belong? c) Deduce the full electron configuration of tungsten d) Deduce the condensed electron configuration of tungsten. a) To what group does phosphorus belong? b) What is the principle quantum number of barium? c) What would be two properties of V? d) How many valence electrons does silicon have? e) What ion will calcium most likely form? Why? f) Write the orbital diagram for copper g) Write the electron configuration for Ge h) Write the condensed electron configuration of iodine