26.1 CLASSIFICATION OF THE ELEMENTS Dimitri Mendeleev (1869) arranged elements in a table in order of increasing mass. He put elements with similar properties in the same column.
36.2 THE PERIODIC LAW CONCEPT H. G.J. Moseley arranged elements in order of increasing atomic number.Periodic Law –elements in the same column have similar properties
4Neils Bohr’s introduction of electron energy levels altered the shape of the Periodic Table. The modern Periodic Table shows s, p, d and f sublevels.
56.3 Organization of the Periodic Table A horizontal row is called a period.A vertical column is called a groupElements in the same group exhibit similar properties.Main Group Elements: A GroupTransition Metals: B Group
6Figure: UNTitle:American Periodic TableCaption:Representative elements are placed in A groups and transition elements in B groups.Notes:Most periodic tables in the U.S. still use this convention, although often the IUPAC convention is also listed.
7Some Group Names to Memorize Group IA: alkali metalsGroup IIA: alkaline earth metalsGroup VIIA: halogensGroup VIIIA: noble gases
8Transition Metals (B group) Inner Transition Metals (beneath the main body of Periodic Table)lanthanide series: Ce-Lu, also called rare earth metalsactinide series: Th-Lr, all radioactive elementsNote: all elements > 93 are man-made in particle accelerators.
10Na F Kr The Alkali metal in the third period is ____ The Halogen in the 2nd period is _____The Noble gas in the fourth period is ____FKr
116.4 Atomic Size: distance from nucleus to outermost electron Increases down a group/columnAs we go , there are more energy levels = bigger radiusIncreases from right to left across a period/row f (weird huh?)As we go , the # protons increases so more positive. As positive charge increases, the electrons are pulled closer, so the atom is actually smaller.
12Trend is like a snowman that fell to the right Trend is increases fi
14Which Is Larger?A) Cl, Se or TeB) Mg, Si or SAnswer: TeAnswer: Mg
15Metallic Character: Increases from right to left f metals are on left-hand sideIncreases down a group iFor groups IVA and VA, we go from nonmetals (C & N) at the top to metals (Sn & Bi) at the bottom.Same snowman trend!Trend is increases fi
166.5 PROPERTIES OF ELEMENTS Elements in the same group typically have similar chemical behavior and physical propertiesFor example, Na reacts with Cl2 to form NaCl and K reacts with Cl2 to form KCl.
17Ex. 1: Sodium reacts violently with water. Which will also? K Mg Al Li PEx. 2: Chlorine reacts with hydrogen to form HCl. Give the formula when fluorine reacts with hydrogen._____K and LiHF
186.7 Valence Electronscore electrons: inner e- in filled electron levelsvalence electrons: s and p e- in the outer unfilled levelvalence electrons form chemical bonds and dictate the properties and chemical behavior
19Valence Electrons number of valence electrons ?: For Group A elements: Group # = # of valence electronsIA IIA IIIA IVA VA VIA VIIA VIIIAValencee-’snumber of valence electrons ?:Si____ Kr____ P____ Na____Ca____ S ____•2 6
206.8 Writing electron dot formulas Write down the element symbolHow many valence electrons?Assume the atom has four sides, and put electrons with one electron per side before pairing. There are a maximum of 2 e– on each side!Let’s try some on the board!!!
216.9 Ionization energy: energy required to remove an electron from a neutral atom. IE increases up a group heasier to remove electrons from a larger atom (e– ‘s are further from the nucleus)IE increases left to right gMetals have low IE’s because they want to lose electrons to be like a noble gasNonmetal elements have high IE’s because they don’t want to lose electrons, they want to gain electrons.*These trends are the opposite of the snowman !Trend is increases gh
23Which has larger IE?A) Cl, P, Ca?B) Li, Rb, Be?A) ClB) Be
246.10 Ion FormationAtoms gain or lose electrons to have same number of valence electrons as a noble gas.Noble gas: charge = 0; very stable, chemically inert, happy with 8 valence electrons (full s and p) except He has full 1s only = 2 e-
25Metals lose electrons and become positively charged ions = cations GroupGroup IA metalsGroup IIA metalsGroup IIIA metalsCharge+1+2+3ExampleLi+Mg2+Al3+magnesium ion can be shown as Mg+2 or Mg2+.The 1 is omitted for +1 or –1
26Nonmetals gain electrons and become negatively charged ions = anions GroupGroup VA nonmetalsGroup VIA nonmetalsGroup VIIA nonmetalsCharge–3–2–1ExampleN3–O2–F–
27What ion do they make? Li+ lithium Mg2+ magnesium S2- Sulfur Br- Al3+lithiummagnesiumSulfurbrominenitrogenaluminum
29Electron Configuration of ions + charge means less e- than the atom– charge means more e- than the atomWrite the electron configuration of the neutral atom first, then remove the correct number of electrons for cations, or add electrons for anions.
30F- is like ? 1) Na+ is like Ne Na atom 1s22s22p63s Na (isoelectronic w/?)2) Mg2+ is like ?Mg atom 1s22s22p63s2Mg (isoelectronic w/?)F- is like ?F atom 1s22s22p5F (isoelectronic w/?)1s22s22p61s22s22p61s22s22p6
31IonIsoelectronic with which Noble gas?Electron ConfigurationK+P3-Cl-Ca2+
32Answers They are all the same 1s22s22p63s23p6 All isoelectronic with Argon
33Example 2: Circle all the ions below that are isoelectronic with neon:
34Coulomb’s Law Law of physics published in 1783 Basically describes how opposites attract.This is VERY important in chemistry as ions of opposite charge attractThe electrostatic attraction between two charges is proportional to the charge magnitude (q) and inversely proportional to the distance (r) squared.F = ke(q1q2 / r2)
35Chapter 6 Self Test Page 169 Try numbers 2-5, 7-16 Answers in Appendix J