Today is Tuesday, September 15 th, 2015 Pre-Class: We will be starting with a concept map today, followed by some information…and stuff… In This Lesson: Compounds, Electron Configuration (Lesson 3 of 9)

Today’s Agenda Concept map review. Review of Guiding Questions. Understand compounds. Diagram electron configuration. Learn bonds (soon). Properties of Water (not as soon but still soon). Where is this in my book? – Academic: p. 35 and following… – Honors: p. 19 and following…

By the end of this lesson… You should be able to identify the basic structure of compounds. You should be able to properly place electrons around a nucleus with respect to energy levels.

Atom Concept Map Review Everyone should copy this down. – Makes for a great study guide… Volunteer(s)?

Guiding Questions Recently we looked at a series of what I called Guiding Questions. For review, here they are…

Guiding Questions (Write these down) 1.Is it okay to use the number of electrons as a measure of atomic number? 2.What happens if you remove or add a proton? 3.What happens if you remove or add a neutron? 4.What happens if you remove or add an electron?

Guiding Question 1 Is it okay to use the number of electrons as a measure of atomic number? –No – in ions, the number of electrons does not equal the atomic number.

Guiding Question 2 What happens if you remove or add a proton? – Adding a proton changes the element! – This does not often happen in nature. – Let’s say you have Hydrogen. It’s got one proton. – We add a proton, so now it has two. Which element has two protons? Helium.

Guiding Question 3 What happens if you remove or add a neutron? – You’ll create a new isotope. – Same element, same number of protons, new number of neutrons, new atomic mass.

Guiding Question 4 What happens if you remove or add an electron? – You’ll create an ion. – An ion is an electrically-charged atom.

Compounds As we learned recently (briefly), a compound is a chemical combination of two or more elements. – Examples of compounds: Water Salt Hydrochloric Acid (stomach acid) Sulfuric Acid (“ouch” acid) Carbon Dioxide Carbonic Acid (similar to soda water) Glucose (simple sugar)

Compounds In compounds, elements are held together by some kind of bond (more on bonds later today/tomorrow). – The smallest unit of an element is called an atom. – The smallest unit of a compound is called a molecule.** Compounds generally form through a chemical reaction, in which bonds are broken, rearranged, or formed. – Speaking of chemical reactions… – Video! Chemical Reactions – NOVA

Compounds vs. Elements Remember that writing an element is as easy as its abbreviation: – H, Cu, Hg, Li, He, O, C Writing a compound means writing all the elements in the compound, as well as how much are in there. – Examples next slide…

Compounds Compound Examples: – Water (H 2 O – 2 Hydrogen atoms and 1 Oxygen atom) – Salt (NaCl – 1 Sodium atom and 1 Chlorine atom) – Hydrochloric Acid (HCl – 1 Hydrogen and 1 Chlorine) – Sulfuric Acid (H 2 SO 4 – 2 Hydrogen, 1 Sulfur, 4 Oxygen) – Carbon Dioxide (CO 2 ) – Carbonic Acid (H 2 CO 3 ) – Glucose (C 6 H 12 O 6 )

Making Compounds As we said, compounds form from bonds. To understand bonds, we need to understand electron configuration. Electron configuration refers to how the electrons are organized in that cloud around the nucleus. Note (but not in your notebooks): What you’re about to hear is the simplified biology version. The chemistry version is MUCH more complicated/realistic.

Electron Configuration In any given atom’s electron cloud, we say there are energy levels or energy shells. By this, we mean that there are levels closer to the nucleus (lower energy levels) and levels further from the nucleus (higher energy levels). Picture on next slide…

Electron Configuration The electrons in the outermost energy shell (however far out that may be) are called valence electrons. Valence electrons are the only ones that matter in bonding.

Electron Configuration “Filling” electron shells with electrons is easy. You already know how to calculate the total number of electrons in an atom or ion. Fill the shells in a pattern. – We won’t often be going higher than atomic number 18 in this class. – Example on next slide.

Electron Configuration Let’s fill the shells of Aluminum, atomic number 13. This means there are how many electrons in an uncharged atom? – 13 Remember the pattern! First shell: 2 Second shell: 8 Third shell: 3 – 3 valence electrons, and the third shell is the valence shell in this case.

From ChemicalElements.com Take a look at the aluminum atomic diagram to the right. What do you see? Another place to look: – David’s Whizzy Periodic Table s/2000/applets/a2.html s/2000/applets/a2.html Linked on my website.

Electron Configuration Now it’s your turn. Fill the shells of the following atoms in your notebooks, and write how many valence electrons there are: – Carbon – Oxygen – Beryllium – Fluorine – Hydrogen – Helium – Neon – Magnesium – Sulfur

Electron Configuration Carbon (Atomic Number 6) – 2, 4 [4 valence electrons] Oxygen (Atomic Number 8) – 2, 6 [6 valence electrons] Beryllium (Atomic Number 4) – 2, 2 [2 valence electrons] Fluorine (Atomic Number 9) – 2, 7 [7 valence electrons]

Electron Configuration Hydrogen (Atomic Number 1) – 1 [1 valence electron] Helium (Atomic Number 2) – 2 [2 valence electrons] – Notice something about helium? Neon (Atomic Number 10) – 2, 8 [8 valence electrons] – Notice something about neon and helium?

Electron Configuration Magnesium (Atomic Number 12) – 2, 8, 2 [2 valence electrons] – Notice something about magnesium and beryllium? Sulfur (Atomic Number 16) – 2, 8, 6 [6 valence electrons] – Notice something about sulfur and oxygen?

Electron Configuration What’s going on with helium and neon? – How many valence electrons? 2 and 8 – How many more can you fit in their outermost energy shells? None! The valence shells are at capacity! These, and all the elements in the same column below them, are called the noble gases. Because their valence shells are full, they don’t really react with anything. – They also were among the last elements to be discovered. Think of a snooty “noble” person. That’s how they were named!

Electron Configuration And what about their location on the periodic table?

Electron Configuration Now what about Beryllium and Magnesium? – How many valence electrons for each? – 2! And how about Oxygen and Sulfur? – 6 each! And what about all of their locations on the table?

Electron Configuration And what about their location on the periodic table?

Electron Configuration There is a pattern to the periodic table for valence electrons! Work by columns (which are called groups). Start from the left and ignore the lower middle part. – The first column or group has 1 valence electron, the second has 2, et cetera. Rows, by the way, are called periods. – Hence, periodic table of elements.

Electron Configuration

Dmitri Mendeleev Looks like he was on to something when he arranged the table…

One last thing… If you’re dealing with an ion (say for example Al 3+ ), make sure you get the new number of electrons. Al 3+ has 13 protons and 10 electrons, so the arrangement is: – First shell: 2 – Second shell: 8 Total: 10 electrons

A “Trailer” for Next Class TED: George Zaidan and Charles Morton – How Atoms Bond

And so now we do the Review and WhipAround… First, play Electron Configuration Matching Game on Quia. Then, try Atomic Structure and Electron Configuration Battleship. Then, try Atomic Structure Review Quiz. – Write both your names in the survey question. Find some space in your notebook and write down two things you learned about: – Electron Configuration – Compounds