Transcript PT trends
BETWEEN YOU AND A PARTNER, GRAB ONE TEXTBOOK… Turn to p. 193 (Organize Elements minilab) Cut a piece of construction paper into 10 squares and write the information for each element on each separate sheet Follow the instructions and answer the questions on a separate sheet (one sheet per pair) FOR QUIZ B Chapter 6 PERIODIC TABLE DEVELOPMENT OF THE PERIODIC TABLE J.W. Dobereiner Early This 1800’s, classify elements in sets of 3 Element Mass Li 7 Na 23 K 39 trend didn’t work for most of the elements known at the time JOHN NEWLANDS 1865 – noticed trend that every 8th element had same properties (law of octaves) Unfortunately, this didn’t work for all the known elements at the time, and it was dismissed MENDELEEV Considered the father of the modern Periodic table arranged by increasing atomic mass (1869) MOSELEY Discovered that the # of protons = atomic number Developed concept of arranging PT by atomic number Periodic law – there is a periodic repetition of properties when elements are arranged by atomic # Periods vs. groups/families Metals vs. nonmetals vs. metalloids What are some properties? Are all nonmetals gases? Representative elements vs. transition metals vs. inner transition metals What do all elements in the same group have in common? Valence electrons All elements in the same group exhibit similar characteristics Sodium and Potassium are both highly reactive in water So, what subatomic particle is responsible for determining properties of an element? How many valence electrons? Alkali metals: 1 valence electron, s block Alkaline earth metals: 2 valence electrons, s block Halogens: 7 valence electrons, s and p block Noble gases: 8 valence, totally filled s and p block, except for which element? Helium – his s block is filled with only 2 Transition metals: (Groups 3B – 12B) 2 s-block electrons, and various d block electrons Called transition metals b/c electrons can move around the d block Inner transition metals: 2 s-block electrons and various f block electrons Representative elements: (Groups 1A – 8A) any of the s or p-block elements SHIELDING SHIELDING Which atom has more shielding? We’ll be coming back to this idea of shielding often ATOMIC RADIUS Half the distance between the nuclei of 2 like atoms No definite edge of electron cloud atomic radius TRENDS IN ATOMIC RADIUS Down the Groups What is changing about the atom as we go down? # of shells = energy level More shells = bigger atom Across the Periods Same period means same # of shells What is changing as we go across a period? Be Li Na K Rb C F Who is larger? Mg or S? Br or K? C or Sn? Who is smaller? Li or N? F or I? Put the following elements in order of increasing atomic radius Ca, Fe, Br, O, Ba WHAT IS AN ION? An ion is an atom with a charge (+ or -) In a sodium atom, how many protons and electrons do we have? How many valence e-? 11 p+ and 11 e 1 valence e Can we lose protons? No, that would change the element OCTET RULE An atom is most stable when it has a full outer shell How many valence electrons = full? An atom will lose or gain electrons to achieve this – whichever is easiest Sodium has 1 valence electron. Do you think he loses or gains? Loses, then there will be 1 more proton than electrons If an atom has 2 valence e-, what will it do? What group is this? What charge? What charge does aluminum form? Lose or gain? +3, loses 3 electrons If an ion is positive it has ______ eIf an ion is negative it has ______ e- SIZE OF IONS (IONIC RADIUS) Na Na+ e- F e- F- Who is larger? Mg or Mg2+? S or S2-? O2- or F1-? First, determine if you have lost or gained electrons… Which particle do you have more of (who has the power?) IONIZATION ENERGY IE is the energy required to remove an electron from an atom (and make it an ION) KEEP SHIELDING IN MIND Babysitter analogy A couple First Ionization Energies: Li = 520 kJ/mol O = 1310 kJ/mol Who is harder to take an electron from? Which has the higher ionization energy? Li or N? Cs or Li? O or S? Which has the lower ionization energy? K or Fe? F or Br? TURN IN PROJECTS UP FRONT… Warm up: As we go down the groups on the PT, the size of the atom __________, making it __________ to take an electron away, making the ionization energy __________ As we go left to right across a period, the size of the atom _________, making the ionization energy __________. Arrange in decreasing ionization energies: Cr, Br, I, Li, N ELECTRONEGATIVITY (EN) How well an element can attract electrons from another element in a bond Atoms fill their outer shells when they bond with another atom How might EN relate to IE? If it’s hard to take an electron away, what kind of attraction do you think it has? What do you think the electronegativity of a noble gas might be? Do they want to bond? Zero Arrange in order of increasing electronegativity: Mg, F, Ne, Cs, Al NOW THE EASY WAY… & OVER IE and EN increase RaDius Decreases UP But it is good to understand the WHY so you can double check yourself… Put in order of decreasing atomic radius: Ca, Al, Ne, Rb, Br, Au, Zn, C What order is this for ionization energy? (increasing or decreasing) Skip #8 Add this question (doesn’t matter where): Determine the larger radius in the following: (what are the the a. Mg or Mg2+ things with charges b. Cl or Cl1called, and how do c. Cl1- or P3they get those charges?) CONTINUE FROM YESTERDAY… Between you and a partner, grab a textbook: Turn to p. 193 (Organize Elements minilab) Cut a piece of construction paper into 10 squares and write the information for each element on each separate sheet Follow the instructions and answer the questions on a separate sheet (one sheet per pair) When finished, turn it in and grab a BINGO card