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Agenda 11/4/2016 Slip Quiz Trends in Properties in the Periodic table explaining the patterns (notes from slides) IUPAC Announces New names for elements Long form periodic table Homework Slip Quiz 1 1. Which of the following has 8 valence electrons? Explain how you decided. antimony, aluminum, argon, arsenic. 2. Which 2 elements in the list would have the same number of valence electrons? How many? How do you know? Correct your answers 1. Which of the following has 8 valence electrons? Explain how you decided. antimony, aluminum, argon, arsenic. Argon has 8 valence electrons - group 18 2 2 6 2 6 2 6 1s 2s 2p 3s 3p [Ne]3s 3p 8 electrons in outermost energy level orbitals antimony, aluminum, argon, arsenic. Antimony and arsenic are in the same group (Grp 15) in the Periodic table and all elements in a group have same number of valence electrons. As electron config. [Ar]3d104s24p3 5 valence electrons This 2D model is useful for thinking about the size of atoms and how they might change along periods and down groups in the periodic table e-e(showing electrons in Energy levels, increasing ee- e- 11+ eeeIn energy as the levels ee- eIncrease in size). Atomic radius vs. Atomic Number (take notes under graph) Group trends in atomic radii Atomic Radii (size of atoms) Main Group Generally Atomic radius increases down a group Nuclear charge increases down a group - electrons are added to successively higher principal energy levels - the orbitals are larger in size. - Generally Atomic radius increases down a group Nuclear charge increases down a group - electrons are added to successively higher principal energy levels - the orbitals are larger in size. - the increased distance offsets the greater pull of the increased nuclear charge - Generally Atomic radius increases down a group Nuclear charge increases down a group - electrons are added to successively higher principal energy levels - the orbitals are larger in size. - the increased distance offsets the greater pull of the increased nuclear charge - Also the electrons in the inner orbitals shield the outermost electrons from the pull of the nucleus Atomic Radii trend across a period Generally Atomic radius decreases across a period Nuclear charge increases across a period - electrons are added to orbitals in the same principal energy level - Generally Atomic radius decreases across a period Nuclear charge increases across a period - electrons are added to orbitals in the same principal energy level - Moving across a period the increased nuclear charge increases the pull of the nucleus on the electrons in the orbitals in that energy level - Generally Atomic radius decreases across a period Nuclear charge increases across a period - electrons are added to orbitals in the same principal energy level - Moving across a period the increased nuclear charge increases the pull of the nucleus on the electrons in the orbitals in that energy level - the outermost electrons are pulled closer to the nucleus and atomic radius gets smaller Note on atomic radius - measuring it - Electron cloud - based on probability - does not have a clearly defined edge - Atomic size defined by how closely an atom lies to a neighboring atom - tends to vary in different substances - For metals - atomic radius is defined as half distance between adjacent nuclei in a crystal of the element Atomic radius vs. ionic radius An ion is an atom or bonded group of atoms that has a positive or negative charge. Atomic radius e- 11+ eeLarger ee- eee- ethan e-e- Ionic radius Sodium atom Sodium ion Na+ Electrically neutral 11+ - 10- = +1 charge Periodic Variation in Chemical Properties is defined as the energy required to remove an electron from a gaseous atom. Ionization energy First ionization energy is energy needed to remove the first electron from a gaseous atom. Periodic Variation in Chemical Properties The higher (larger) the ionization energy value is, the more energy is required to remove that electron from its gaseous atom (in other words, the more strongly the nucleus of the atom is attracting that electron). p 167 Generally ionization energy _______ down a group p 167 p 167 p 167 Generally ionization energy decreases down a group Nuclear charge increases down a group but: - electrons are added to successively higher principal energy levels - the orbitals are larger in size. - the increased distance and the shielding by inner electrons offsets the greater attraction between the nucleus and the outermost electrons Therefore, it takes less energy to remove an electron from the larger atoms in the group. Generally ionization energy ____________ across a period - p 167 Generally ionization energy increases across a period Nuclear charge increases across a period, but: - Therefore ... Generally ionization energy increases across a period Nuclear charge increases across a period - electrons are added to orbitals in the same principal energy level - Moving across a period the increased nuclear charge increases the attraction between the nucleus and the electrons in the orbitals in that energy level Therefore it is more difficult (takes more energy) to remove an electron from the atoms as we move across the period. Electronegativity is defined as the relative ability of an atom to attract electrons towards itself through a chemical bond. Measured in units called Paulings. (We leave out noble gases, they form too few compounds to collect sufficient data.) Variation in Electronegativity in Paulings Group and Periodic Trends in Electronegativity? Generally electronegativity ____________ down a group Generally electronegativity __________ across a period Group and Periodic Trends in Electronegativity? Generally electronegativity decreases down a group Generally electronegativity increases across a period As we read the IUPAC announcement Notice how scientists communicate with each other. Notice what is involved in naming new elements currently. 115 Ds Rg Cn Nh Fl Mc 116 Lv 117 118 Ts Og Long Form Periodic Table Cut and stick the periodic table you have: Long Form Periodic Table Use what we learned Cut and stick the periodic table you have: from creating the left step periodic table to make sure La and Ac are in the f block and Lu and Lr in the d block. Long form Periodic table - shade or label the 4 blocks somehow - you decide where you want H and He. Fold to hide the transition elements Put a title on this format : Main Group Elements (Representative elements) Electrons in atoms Chapter 5 Notes packet to fill in some of the gaps between what I’ve said and you’ve researched or discovered using the simulations and to re-kindle what you learned about waves in physics earlier. Homework Ch 5. The Electrons - notes packet Unit 3 The Periodic Table and Electrons Study Guide for Content Mastery Review graphing checklist also. Test on Thursday, Nov 10th.