2Transition from metal to non-metals Earth MetalsTransition from metal to non-metals AlkaliGroup IAlkalineGroup IIHalogen GasesGroup VIINoble GasesGroup VIII1H 1+2He3Li 1+2,14Be 2+2,25B 2+2,36C 4+2,47N 3-2,58O 2-2,69F 1-2,710Ne2,811Na 1+2,8,112Mg 2+2,8,213Al 2+2,8,314Si 4+2,8,415P 3-2,8,516S 2-2,8,617Cl 1-2,8,718Ar2,8,819K 1+2,8,8,120Ca 2+2,8,8,2
3Valence ElectronsThe Outer Electron shell is the most important shell discussed in chemistryIt is called the Valence Electron ShellThe Electrons that occupied that shell are called Valence ElectronsThey are at the highestEnergy state
4The Most Important Thing The number of valence electrons determines how an atom bonds with other atoms. Valence electrons cause chemical bonding to occur.# of valence electronsSo why do elements in the same group have similar chemical properties?
5Elements and Compounds Elements are all the different materials in the periodic table they are one type of substance.If you can find it in the periodic table it is an element!Compounds are made up of more than one type of element.To make a compound, elements are chemically bonded together.
6Element Vs CompoundsAluminiumWaterBoronCarbon DioxideHelium
11Transition from metal to non-metals Very Reactive MetalsEarth MetalsTransition from metal to non-metals AlkaliGroup IAlkalineGroup IIHalogen GasesGroup VIINoble GasesGroup VIII1H 1+2He3Li 1+2,14Be 2+2,25B 2+2,36C 4+2,47N 3-2,58O 2-2,69F 1-2,710Ne2,811Na 1+2,8,112Mg 2+2,8,213Al 2+2,8,314Si 4+2,8,415P 3-2,8,516S 2-2,8,617Cl 1-2,8,718Ar2,8,819K 1+2,8,8,120Ca 2+2,8,8,2
12Forming Ionic Bonds Potassium (K) and Fluorine (F) Magnesium (Mg) and Chlorine (Cl)Sodium (Na) and Oxygen (O)Calcium (Ca) and Sulfur (S)Do you see something in common with these combinations?Hydrogen (H) and Chlorine (Cl)Hydrogen a metal or non-metal?Non-metal at normal temperature and pressure... But becomes theoretically a metal at very high pressures!REMEMBER “non-metals and metals form ionic bonds”Also Hydrogen is special as it can form ionic bonds with non- metals and metals as well even though it is a non-metal normally!
13Exceptions to the Octet Rule Hydrogen (H) only has one electron on the outer shell, thus requires another one to form bonds so that it has 2 valence electrons.
14Input TimeIONIC BONDSubstance formed when electrons are transferred between 2 or more substances making ions. Happens between Metals and Non-metals The ions have an electrostatic attraction with each other to form an Ionic Bond.
15Octet Rule Atoms want 8 (or 0) valence electrons Wants to be a noble gas!! As in…wants to have a complete valence shell
17Lets try to draw some covalent bonds! Potassium (K) and Chloride (Cl)Valency of K and Cl?Octet Rule Applied!Don’t Forget to write the formula too!!
18Lets try to draw some ionic bonds! Magnesium (Mg) and Chlorine (Cl)Valency of Mg and Cl?Octet Rule Applied!Don’t Forget to write the formula too!!Input Time
19COVALENT BOND Bond formed by the sharing of electrons between (non metal - nonmetal)
20Two fluoride atoms share one electron each to forms a covalent bond. Covalent bonds also follow the Octet Rule (8 valence electrons each)(except for very special cases like hydrogen 2 valence electrons)Molecules are neutral groups of atoms held together by covalent bonds!
21THIS IS A WATER MOLECULE!!!!! Covalent Bonds: Hydrogen Shares electron with oxygen and vice versa!What are these two elements?Are they metal or non-metals?What type of bond would they form? Remember Hydrogen is specialWhen bonding don’t worry about the inner electrons!!!New count the valence electrons! Make sure there is 8 or two for hydrogenUh-oh not enough!!!Find another atom to complete the share!
23Sharing one pair creates Single Bonds Sharing four electrons creates Double BondsSharing one pair and a second separate pairSharing four separate pairsInput Time
24Summary of The Octet Rule Input TimeREMEMBER!All elements want to be like noble gasesThus they want full electron shells.Full electron shell are 8 valence electrons.The Octet RuleAtoms form chemical bonds so that they have an octet of valence electrons. Either byGaining, losing valence electrons orSharing valence electrons.In other words: When atoms bond together, they each want a set of 8 valence electrons. (except for hydrogen who wants two)
25DRAWING MOLECULAR STRUCTURES Electron Dot DiagramLewis Dot DiagramStructural Formula
26Electron Dot DiagramsElectron dot notation is a way of showing how many valence electrons an element has.HHeLiBeBCNOFNe
27Lewis and Structural Lewis structures Input TimeLewis structuresLone pairs are unshared electrons, which are not involved in chemical bonding. (Dotted Pairs)Shared electrons are involved in chemical bonding. (Line)Structural formulasdo not show dots for lone pairs of electrons.FFFF
28How to Draw the Bonds F F F F Step 1: Figure out how many more valence electrons each atom needs to make an octet (F needs 1).FFStep 2: Make sure all elements in the molecule can have an octet.FStep 3: Draw the Lewis structure.FStep 4: Write the structural formula.
29Hydrogen Fluoride (HF) Hydrogen Gas (H)2 Make sure all atoms have octets(H only wants 2 valence electrons).HFHHFHLewis StructureHFHStructural Formula
34mono- (use only for oxygen) Input TimeNaming CompoundsNumber of atomsPrefix1mono- (use only for oxygen)2di-3tri-4tetra-5penta-6hexa-7hepta-8octa-ExamplesP2O5 - this is named diphosphorus pentoxide, because there are two phosphorus atoms and five oxygen atoms. CO - this is carbon monoxide (you need the "mono-" because there's only one oxygen atom). CF4 - this is carbon tetrafluoride, because there's one carbon atom and four fluorine atoms.
35WHICH IS BOND STRONGER?Ionic bonds are a bit stronger than Covalent bonds but both are strong bonds
36Strength of ionic compounds Input TimeIn an ionic compound the ionic bonds are spread evenly through the whole substance as a network so they are generally very strong with high melting points.They tend to made solids compounds
37Strength of covalent molecules In a covalent molecule each molecule has strong covalent bonds inside it.It has weaker attractions between the molecule.Often simple molecular chemicals are gases and liquids.Though the intermolecular bonds are weak the molecular bonds are strongInput Time
38Quiz1. Draw the electron dot notation for Calcium (atomic number = 20).Draw the Lewis structure for a molecule with 1 hydrogen atom and 1 chlorine atom, HCl (atomic numbers = 1, 17).Book Exercises - Section 2.2 over to you questions, All of it!!!