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Trends of the Periodic Table Class #3

Trends of the Periodic Table Class #3. Our Investigation Into Net Nuclear Charge Trends Metallic + Non-Metallic Property Trends 1st Ionization Energy Trends.  Take out your periodic tables now.

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Trends of the Periodic Table Class #3

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  1. Trends of the Periodic Table Class #3 Our Investigation Into Net Nuclear Charge Trends Metallic + Non-Metallic Property Trends 1st Ionization Energy Trends.  Take out your periodic tables now.

  2. Net Nuclear Charge is very easy to “get”. Once you get passed the definition of what the heck it is, you’ll understand. If you have a $10 in your pants pocket, and an IOU for $6 in another pocket, your “net” worth is just FOUR BUCKS. That’s $10 - $6 = $4. The “net” part means the sum of. In this nutty example, the sum of your finances can be quickly calculated by summing up all your assets ($10) and then subtracting all of your liabilities ($6). The net sum of these is your NET WORTH. The NET NUCLEAR CHARGE means, what is the net sum of all the charges in the nucleus of the atom you are measuring? Before we do calculations, what particles are in the nucleus? What are their charges?

  3. Every atom’s nucleus has just protons (positive charges) and neutrons (no charges). The sum of positive charges with neutral charges is always positive. The NET NUCLEAR CHARGE for any atom is that atomic number, with a + sign. Fill in this chart quickly

  4. Every atom’s nucleus has just protons (positive charges) and neutrons (no charges). The sum of positive charges with neutral charges is always positive. The NET NUCLEAR CHARGE for any atom is that atomic number, with a + sign. Fill in this chart quickly That was easy!

  5. What is the group trend for net nuclear charge? What is the period trend for net nuclear charge?

  6. The net nuclear charge for any atom is always that atom’s atomic number with a + sign. The nucleus of any atom contains a certain number of positive protons an, an irrelevant number of neutral neutrons (since neutrons have NO charge).

  7. Metals are atoms with certain properties. They are on the “left” side of the table. Non-metals are atoms with other properties, they are on the “right” side of the table. Metal Properties include: being malleable and ductile, have the ability to conduct heat and electricity, they form cations not anions, they are shiny (have luster), they are dense, they have lower specific heat capacity constants, etc. Non-metal Properties include: not being malleable or ductile (they are brittle or not even solids), not conducting heat or electricity well, they only form anions (the noble gases don’t form ions at all), they aren’t lustrous (most are gases!), they are less dense and usually have higher specific heat capacity constants.

  8. We won’t do this, but you can be assured someone has, and if you were to make a measure and compare all the metals together in every category, which one would have the most luster, and the most cation forming ability, and be best in all the other ways? The winner is francium. In fact, the easy way to “know” which metal is more metallic than other metals is by its proximity to Fr on the table. The closer a metal is to the bottom left corner of the table, the more metallic it is. For example, which metal is more metallic: tantalum or gold? Which metal is more metallic tin or gold? This is too easy! Turns out most non-metallic of all is helium. The closer on the table an atom is to helium, the more non-metallic like it’s qualities. Which is more nonmetallic: chlorine or boron? How about argon or radon?

  9. First Ionization energy is more tricky because it has a funky definition. First, the unit is kilojoules per mole. It is a measure of how much energy it takes to do something. If you had a mole of sodium atoms (23 grams) and wanted to have instead, one mole of Na+1 cations, those electrons don’t just fall off. You have to take them off. Check table S, how much energy does this take?

  10. To remove a mole of electrons from a mole of sodium atoms takes 496 kJ/mole. Your mission, if you choose to accept it, fill in the charts here, determine the group trend for 1st Ionization energy and the period trend for 1st ionization energy now.

  11. To remove a mole of electrons from a mole of sodium atoms takes 496 kJ/mole. Your mission, if you choose to accept it, fill in the charts here, determine the group trend for 1st Ionization energy and the period trend for 1st ionization energy now. It apparently gets “easier”, or takes less energy to remove a whole mole of valence electrons as you move down a period. WHY???

  12. To remove a mole of electrons from a mole of sodium atoms takes 496 kJ/mole. Your mission, if you choose to accept it, fill in the charts here, determine the group trend for 1st Ionization energy and the period trend for 1st ionization energy now. Their valence electrons just keep getting FURTHER and FURTHER from the positive nucleus, they are just easier to pull off the atoms.

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  14. In Lithium, the outermost electron is in the 2nd orbital. In sodium, the outermost electron is in the 3rd orbital. In every atom going down a period, the outermost electron that would be removed is further and further away from the positive nucleus. It takes less and less energy to pluck off those outermost electrons from bigger and bigger atoms going down each group. The group trend for 1st ionization energy is decreasing.

  15. Time to figure out the period trend for 1st ionization energy. Let’s use period 2 and period 5 (five atoms in a row from each…

  16. Time to figure out the period trend for 1st ionization energy. Let’s use period 2 and period 5 (five atoms in a row from each…

  17. It’s clear that there is an exception in the 2nd period, but the period trend for 1st Ionization energy is (clearly) increasing. Why? What’s going on inside these atoms that makes this energy demand drop going across the table? For the same reason that the atoms get smaller going across the table (same number of orbitals, more and more protons in the nucleus pulling tighter and tighter), the outer electrons get harder and harder to pull off.

  18. The group trend for 1st Ionization energy is decreasing, because removing the outmost electron gets easier as the electrons move further from the nucleus. The period trend for 1st Ionization energy is increasing, because removing the outmost electron gets harder as the electrons move closer to the nucleus. This happens because the atoms of a period all have the same number of electron orbitals, but more and more protons. As they get physically SMALLER in radius, their electrons are harder to remove because the electrons are closer to the nucleus.

  19. Tonight, please do HW 1 + 2 + 3 Sounds like a lot, but it will take 10 minutes at most.

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