Warm Up- Complete the table AtomNeutronsProtonsElectronsCharge Al-2610 Ca-402+ P-290 How does Al-26 differ from Al-27? How does an atom differ from an ion?

How did you do? AtomNeutronsProtonsElectronsCharge Al Ca P How does Al-26 differ from Al-27? How does an atom differ from an ion?

As we think about why the trends occur…. We need to remember what we know about Coulombic attraction. 1. What is a coulombic attraction? 2. What did you notice about the attractive force going down a group? 3. Is the attractive force of the nucleus divided up among the electrons or does each electron get the full force? 4. What happens to the attractive force going across a period? Why?

Work on the Trends Activity If you finish answering all the questions and identify the trends. Give some thought to explaining the trends. 25 minutes???

Chemical Periodicity Chapter 5 Periodic Trends in Atomic Size Periodic Trends in Ionization Energy Periodic Trends in Ionic Size Periodic Trends in Electronegativity

Periodic Trends in Atomic Size The boundary of an atom can't be measured directly Atomic Radius: half the distance between nuclei of two like atoms.

Draw the Bohr model for Li, K and F Look at the position of these elements on the Periodic Table. Can you detect a “trend” in size as you go down a group? What is the trend is going across a period? Does this align with what you saw in the activity?

Explain the trend in your own words! Atomic size increases down a group –What happens to the energy level as we go down a group? Where are the electrons? Atomic size decreases from left to right –Where are the electrons? –the nucleus has more attraction to the electrons

Periodic Trends in Atomic Size

Which would be bigger? a. Sodium or Aluminum b. Magnesium or Barium c. Nickel or Bromine d. Calcium or Yttrium e. Describe in your own words why atoms in the same period decrease in size from left to right.

Was there a trend in Melting Point? file:///Users/teacher/Desktop/Melting%20poi nt%20trend file:///Users/teacher/Desktop/Melting%20poi nt%20trend

Periodic Trends in Ionization Energy Ionization Energy: –Energy required to overcome the attraction of the nucleus and remove an electron.

Write the EC for Li, Na and N and F Explain the trend in ionization energy!

Write the EC for Li, Na and N and F Ionization energy decreases as you move down a group because electrons are further away so they are easier to strip off. Ionization energy increases as you move left to right, for representative elements because the attraction by the nucleus is stronger so it is harder to pull electrons away.

Warm Up The density of bone is 1.85 g/cm 3. If your pinky finger has a mass of 20.0g, what is it’s volume? Would your pinky bone sink or float?

Look at the Table of Ionization Energies First ionization energy- energy necessary to remove the 1 st electron Second ionization energy- energy necessary to remove the 2nd electron. Third ionization energy- energy necessary to remove the 3 rd electron.

How does becoming an ion affect the size of the atom?

Periodic Trends in Ionic Size Let’s look at Li and F again. If each atom wants to achieve a full outer energy level (full octet)…. What has to happen to the electrons? When they gain or lose electrons, what do they become? What happens to the size of the atom?

Periodic Trends in Ionic Size Anions are atoms that have gained electrons and have an overall negative charge. Anions are larger than the atoms from which they have formed. Why?

Cations are atoms that have lost an electron and have an overall positive charge. Cations are smaller than the atom from which they have formed.

Check it out!

Periodic Trends in Ionic Size Cations decrease in the size from left to right. Anions decrease in size from left to right As you move down a group the radius increases because of more electrons in higher energy levels

Which atom is the largest? Mg or Mg 2+ O or O 2- Cu 2+ or Cu 4+ Write a rule that will help you get these right every time!

Isoelectronic Na 1+, Ne and F 1- are said to be Isoelectronic. Na 1+, Ne and F 1- are said to be Isoelectronic. a. Determine the electron configuration for each of the atoms b. Define isoelectronic

Isoelectronic 1. Write a 2- ion that is isoelectronic with Mg Write 3 ions that are isoelectronic with Kr 3. Write 2 ions that are isoelectonic with Ni

Trends in Electronegativity Electronegativity: –The tendency of an element to attract electrons when in a chemical bond. Let’s look at Li, Cs and F

Let’s look at your table of electronegativities. Electronegativity table: –Noble gases are left out because they do not form compounds. –Metals have low electronegativity numbers because they want to give electrons away, not attract them. –Nonmetals have high electronegativity numbers because they attract electrons to make their configurations more stable

Trends in Electronegativity

Element Reactivity What would make an element reactive? Which elements are most reactive? What would make an element unreactive? Which elements would be most unreactive?

Video Metal Reactivity Clip pYrY

Warm Up: In CB Which is more electronegative? Use the trend, then check them using the table. Al or Cl? Ca or Ba? Ga or S I or Cl? W or Zn?

What is Nuclear Shielding? Nuclear Shielding is the phenomenon that occurs that helps also helpsexplain some of the trends. Draw the Bohr Model for Phosphorus. Which electrons are feeling the full effect of the nucleus?

Sheilding Inner shell electrons “shield” the nucleus. This allows for electron, electron repulsion to have a greater effect on the atom.

Warm Up- Fill in the following table (p.159 may help) Atom Metal or nonmetal? Stable ion Size relative to neutral atom Larger or smaller than S 2- P Rb Cl Be Al

How did you do? Atom Metal or nonmetal? Stable ion Size relative to neutral atom Larger or smaller than S 2- Pnm P 3- largerlarger Rbm Rb 1+ smallersmaller Clnm Cl 1- largersmaller Bem Be 2+ smallersmaller Alm Al 3+ smallersmaller