Why is the periodic table shaped like it is and how are the elements arranged?
The Periodic Table - History Two scientists, Dimitri Mendeleev (Russia) and Lothar Meyer (Germany) properties of elements did not change smoothly with increasing atomic mas. Instead the properties of the elements repeated periodically. Periodic Law: the properties of the elements repeat periodically as the elements are arranged in order of increasing atomic number (# of protons) This periodic law is used to form the Periodic Table
II. The Periodic Table • John Alexander Newlands • Arranged elements in order of increasing atomic masses • Noticed some properties recurring over and over again – he called this the periodic law • Dmitri Mendeleev • Published the periodic table of elements • Very confident as he left spaces empty – assumed those elements were not yet discovered
Vertically into Groups Horizontally Into Periods Elements are arranged:
Groups of Elements • Vertical columns on the periodic table • Similar physical properties • Similar chemical properties
If you looked at one atom of every element in a group you would see… Each atom has the same number of electrons in it’s outermost shell.
105 Db 107 Bh Valence Electrons for group A elements sblock pblock 0 +1 Charge on stable monatomic ion ± 4 +3 -3 -2 -1 ns2np6 ns1 +2 ns2np3 ns2np1 ns2np2 ns2np4 ns2np5 ns2 8A 1A 3A 4A 5A 6A 7A 2A Group B Period number gives shell (n)
Elements are arranged according to atomic # and e- configuration. Li: 3 e-’s 1s22s1 Na: 11 e-’s 1s2 2s2 2p63s1 K: 19 e-’s 1s2 2s2 2p6 3s2 3p64s1 Paramagnetic or diamagnetic?
Valence orbitals: outer shell orbitals beyond the closest noble-gas configuration Valence electrons: “the ones that can react” (located in the valence orbitals). The other e-’s are called core electrons and don’t react. 2s2 3s2 4s2 5s2 6s2 7s2 Elements in a vertical row have the same number of valence electrons.
The number of outer or “valence” electrons in an atom effects the way an atom bonds. • The way an atom bonds determines many properties of the element. • This is why elements within a group usually have similar properties.
If you looked at an atom from each element in a period you would see…
The elements in the same horizontal row are called a period Details of the Periodic Table - Period Hydrogen and Helium are in period 1 Lithium through Neon are in period 2 4
Periods on the Periodic Table 1 2 3 4 5 6
The period 4 atoms each have 4 electroncontaining shells 4th Shell K (Potassium) Atom Kr (Krypton) Atom Fe (Iron) Atom
Sublevel Blocks s1 s2p1 p2 p3 p4 p5 p6 1 2 3d1 - d10 4 5 6 f1 - f14
Electronic Structure sblock pblock dblock 105 Db 107 Bh fblock
Condensed Ground-State Electron Configurations in the First Three Periods
Los Alamos National Laboratory's Chemistry Division Periodic Table of the Elements noble gases non-metals +1 metals +2 +3 -3 -2 -1 typical charge on ion in binary compound atomic number atomic mass transition metals http://pearl1.lanl.gov/periodic/default.htm
Physical States at Room Conditions gases liquids solids 105 Db 107 Bh Modified from http://www.cem.msu.edu/~djm/cem384/ptable.html
Natural vs. Man-Made Elements natural elements man-made elements not found on Earth 105 Db 107 Bh
MolecularNature of Free Elements diatomic tetratomic octatomic 105 Db 107 Bh All other free elements are atomic in nature.
All Isotopes Radioactive no stable forms 105 Db 107 Bh
105 Db 107 Bh Hydride Chemistry (binary hydrogen compounds) ionic covalent polymeric salts with H- molecules with +1 chains with H-to-H bonds 8A 1A 3A 4A 5A 6A 7A 2A metallic interstitial H2 Group B mostly gases, some liquids solids
Each group has distinct properties • The periodic Table is divided into several groups based on the properties of different atoms.
Groups of Elements • Alkali Metals: • Group 1 metals • Soft, silver coloured metals that react violently with H2O to form basic solutions • Most reactive: cesium & francium
Alkali Metals reacting with water: • Li (Lithium) • Na (Sodium) • K (Potassium) • Rb (Rubidium) • Cs (Cesium) What would you expect from Francium?!?!
Potassium (K), in Water (H2O) Alkali metals Soft, silvery colored metals Very reactive!!!
Alkali Metal Family Li K Na
Alkaline Earth Metals Silvery-White Metals Fairly reactive Many are found in rocks in the earth’s crust
Halogens: • Group VII A, non-metals, highly reactive. • Fluorine is the most reactive Noble Gases: -Group VIII A - Generally unreactive
TheHalogenFamily Cl2(g) I2(s) Br2(l)
Chlorine (Cl) Bromine (Br) and Iodine (I) Halogens Most are Poisonous Fairly reactive Chlorine Gas was used as a chemical weapon during World War I. It was used by the Nazis in World War II.
Colors Noble Gases produce in lamp tubes(discharge tubes): • Ne (Neon): orange-red • Hg (Mercury): light blue • Ar (Argon): pale lavender • He (Helium): pale peach • Kr (Krypton):pale silver • Xe (Xenon): pale, deep blue
Transition Metals: Most are good Conductors of heat and electricity Ductile and malleable (easily bent/hammered into wires or sheets) .Metalloids: Metals very close to the “staircase” line They have properties of metals and non-metals. • Si (Silicon) and Ge • (Germanium) are very • important “semi-conductors”