Bonding
A chemical bond is a force that holds two or more atoms together.
Compound two or more elements chemically combined by gaining, losing, or sharing electrons. Molecule a particle made of 2 or more atoms covalently bonded together.
Electrons closest to the nucleus - least amount of energy and lowest energy level. farthest from the nucleusthe greatest amount of energy and are in the highest energy level. Aurora Borealis
Outermost electrons are easily attracted to the positively charged nucleus of other atoms. This forms a chemical bond. These outermost electrons are called valence electrons.
Use the Periodic table to determine the number of valence electrons. Groups 1,2, 13 18 have the same number of valence electrons as the ones digit of the group number,except helium which only has 2. Groups 3-12 vary in numbers of valence electrons.
Lewis Electron Dot Diagram p. 271 Lewis Electron Dot diagram is a model that represents valence electrons in an atom as dots around the element s chemical symbol. Elements with unpaired dot are reactive or chemically unstable. Atoms will bond to other atoms to become chemically stable.
Electron Dot Diagram Practice Beryllium Hydrogen Sodium Chlorine Stable or unstable? # Bonds Stable or unstable? # Bonds Stable or unstable? # Bonds Stable or unstable? # Bonds Helium Neon Calcium Nitrogen Stable or unstable? # Bonds Stable or unstable? # Bonds Stable or unstable? # Bonds Stable or unstable? # Bonds
Isotopes Isotopes : are atoms of the same element with different numbers of neutrons. Example: Isotopes of the element, carbon. Carbon - 12 6 protons 6 neutrons Carbon - 14 6 protons 8 neutrons The same element, same number of protons, different number of neutrons. (If proton number changes, element changes)
Ions Ion an atom or group of atoms that has become electrically charged. It is a charged particle. When an atom loses an electron, it loses a negative charge and becomes a positive ion. When an atom gains an electron, it gains a negative charge and becomes a negative ion.
Ionic Bond (Metal to NonMetal) Ionic Bond the attraction between two oppositely charged ions. An ionic bond is formed when atoms gain or lose electrons. Ionic bonds form compounds.
Ionic bond
Predicting Reactions Between Elements Metals react with nonmetals to form ionic compounds. Will Na react with Br? Will Ca react with Ag? Will S react with Cl?
Homework Check Sodium & Calcium - no -two metals metallic Hydrogen & Oxygen - Potassium & Bromine Francium & Fluorine - Helium & Carbon - Magnesium & Chlorine - Neon & Argon - Nickel & Copper - Phosphorus & Oxygen - Calcium& Uranium -
Homework Check Sodium & Calcium - no -two metals metallic Hydrogen & Oxygen -no two nonmetal covalent Potassium & Bromine yes -metal +nonmetal Francium & Fluorine - yes metal + nonmetal Helium & Carbon - no two nonmetals covalent Magnesium & Chlorine - yes metal+ nonmetal Neon & Argon - no - two nonmetals covalent Nickel & Copper - no two metals metallic Phosphorus & Oxygen - no two nonmetals cov Calcium& Uranium - no two metals metallic
Covalent Bond (nonmetal to nonmetal) Covalent Bonding A type of bonding in which two or more atoms share one or more pairs of valance electrons. When covalent bonding occurs, molecules are formed.
Covalent Bond
3 Types of Covalent Bonds Single covalent bond atoms share one pair of valence electrons. Double covalent bond atoms share two pairs of valence electrons. Triple covalent bond atoms share three pairs of valence electrons.
Common Covalent Bonds The more valence electrons that two atoms share, the stronger the covalent bond is between the atoms. Examples : H 2 0 CO 2 N 2 C 6 H 12 O 6 H 2
Metallic Bonds (metal to metal) Metallic Bond Bond formed when many metal atoms share their pooled valence electrons. Valence electrons are not bonded to one atom but positive ions are surrounded by a sea of electrons Ex: Aluminum
Metallic Bond
Chemical Formulas Chemical formulas a group of chemical symbols and numbers that represent the number of atoms of each element that make up a compound. ( H O) 2 In a chemical formula, the element with the positive charge is always written first.
Subscripts Subscript the number that shows how many atoms of an element are in the compound. Examples H 0, CO 2 2 The number 2 is the subscript in each.
Valence Numbers Valence number The number of electrons an atom needs to gain, lose, or share to become stable. (Gain electrons negative valence) (Lose electrons positive valence.)
Binary Compound a compound composed of ONLY 2 elements. Polyatomic Ion- a group of positively or negatively charged covalently bonded atoms.
How to Write Formulas 1. Write the symbol correctly for both elements. 2. Write the valence number above each symbol. Make sure you have a positive first, and then a negative. 3. Criss-cross valences to make a subscript. 4. NEVER write 1 as a subscript. (It is understood to be 1 if there is no number.) 5. Reduce to lowest terms.
Examples Sodium Chloride Aluminum Oxide Copper (I) Sulfide Iron (III) Iodide
1. Calcium Sulfide 2. Copper (I)Iodide 3. Potassium Chloride 4. Iron(III) Bromide 5. Sodium Nitride 6. Antimony (V) Oxide
Problem check 1. Calcium Sulfide 2. Copper (I)Iodide CaS CuI 3. Potassium Chloride 4. Iron(III) Bromide KCl FeBr 3 5. Sodium Nitride 6. Antimony (V) Oxide Na 3 N Sb 2 O 5
Practice Problems Aluminum Bromide Magnesium Nitride Calcium Iodide Potassium Sulfide Copper (I) Chloride Barium Fluoride Hydrogen Oxide Lead Bromide
Aluminum Bromide Practice Problems Magnesium Nitride AlBr 3 Mg 3 N 2 Calcium Iodide Potassium Sulfide CaI 2 K 2 S Copper (I) Chloride Barium Fluoride CuCl Ba F 2 Hydrogen Oxide Lead Bromide H 2 O PbBr 2
Practice Problems 1. Lead Iodide 2. Barium Fluoride 3. Tin (II) Nitride 4. Lithium Chloride 5. Sodium Bromide 6. Iron (II) Oxide
7. Potassium Fluoride 8. Silver Bromide 9. Calcium Chloride 10. Copper (I) Iodide 11. Aluminum Nitride 12. Cobalt (II) Sulfide
Practice Problems 1. PbI 2 2. BaF 2 3. Sn 3 N 2 4. LiCl 5. NaBr 6. FeO 7. KF 8. AgBr 9. CaCl 2 10. CuI 11. AlN 12. CoS
Calcium Phosphate Tin (IV) Chromate Ammonium Oxide Magnesium Sulfate
Naming compounds change the ending of the second element to ide. (Do not change the names of polyatomic ions.) Check to see if Roman numeral is needed. Ex: NaCl - Sodium Chloride Fe O Iron (III) Oxide 2 3
Homework Check 1. K 2 O 6. Ca 3 (PO 4 ) 2 2. NaC 2 H 3 O 2 7. FeBr 2 3. Ag 2 SO 4 8. HClO 3 4. ZnCO 3 9. MgSO 3 5. CrS 10. (NH 4 ) 3 PO 4
Homework Check Cd CrO 4 Cu(ClO 3 ) 2 Al 2 O 3 PbC 2 O 4 FePO 4 KClO 3 AgNO 3 SnS 2 NaClO 2 SbCl 5 ZnI 2 Li 3 PO 4
Predicting Reactions between Elements To form an ionic bond, a metal bonds to a non-metal. Metals to the left of stair-step line except H. Non-metals to the right of stair-step line, except H Metalloids along stair-step except Al which is a metal.
Properties of compounds. See handout and p. 288 in textbook.
Naming Compounds Examples Zn 3 N 2 K 2 SO 3 CuO Ba(C 2 H 3 O 2 ) 2
Homework check 1.Iron (ll) Hydroxide 2. Aluminum Perchlorate 3. Chromium (ll) Acetate 4. Tin (lv) Chloride 5. Lead Chromate 6. Copper (ll) Sulfide 7. Potassium Hypochlorite 8. Mercury (ll) Dichromate 9. Calcium Hydroxide 10. Tin (ll) Sulfite
Homework check 11. Zinc Phosphate 12. Barium Fluoride 13. Sodium Nitrate 14. Cadmium Carbonate 15. Mercury (ll) Peroxide 16. Iron (lll) Sulfite 17. Antimony (V) Oxide 18. Copper(l) Permanganate 19. Chromium (lll) Oxalate 20. Ammonium Sulfate
Homework check Chlorine - nonmetal Boron - metalloid Zinc - metal Neon - nonmetal Sodium - metal Silver - metal Silicon - metalloid Helium - nonmetal Bromine - nonmetal Francium - metal Aluminum - metal Calcium - metal Hydrogen - nonmetal Nickel - metal Magnesium - metal Fluorine - nonmetal Potassium - metal Uranium - metal Carbon - nonmetal Argon - nonmetal
1.Ammonium Phosphate 11. Manganese(ll) Oxide 2. Iron (ll) Bromide 12. Tin (lv) Iodide 3. Hydrogen Chlorate 13. Calcium Oxide 4. Sodium Acetate 14. Potassium Chloride 5. Silver Sulfate 15. Copper (l) Hydroxide 6. Chromium (lll) Sulfide 16. Ammonium Sulfide 7. Potassium Oxide 17. Aluminum Carbonate 8. Tin (ll) Oxide 18. Hydrogen Sulfite 9. Copper (ll) Phosphate 19. Iron (lll) Sulfate 10. Zinc Sulfate 20. Aluminum Nitride