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1. Chemical Bonding. 2. GOALS. 1. Compare & contrast ionic and covalent bonds in terms of electron position. 2. Predict formulas for stable binary ionic compounds based on balance of charges. 4. Apply the Law of Conservation of Matter by balancing the following types of
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1 Chemical Bonding
2 GOALS 1. Compare & contrast ionic and covalent bonds in terms of electron position. 2. Predict formulas for stable binary ionic compounds based on balance of charges. 4. Apply the Law of Conservation of Matter by balancing the following types of chemical equations: • Synthesis • Decomposition • Single Replacement • Double Replacement
3 Why do Atoms Form Compounds? • Stability. • What makes an atom stable? • Full outer energy level. • Eight. • Chart page 576.
4 • A Chemical Bond holds atoms together in a compound. • Two basic types: • Ionic • Covalent
Ionic Bonding 5 Transfer of electrons from one atom to another atom. Occurs between metals and nonmetals. Remember: Atoms need a full outer energy level to be stable. EIGHT!
6 Occurs between metals and nonmetals. Metals are electron donors. Non-metals are electron accepters. Called compounds.
8 OPPOSITES ATTRACT!
9 Ionic Bonding CLIP
10 Covalent Bonding Occurs between nonmetals and nonmetals. The sharing of electrons between atoms. Called Molecules.
12 Hydrogen and Fluorine Hydrogen and Chlorine
13 Single, Double, Triple
15 Unequal Sharing δ+ δ_ Polar When one atom has a Greater Positive charge
CO2 H2O NaCl MgCl NO2 H2SO4 NaF NaPO4 HCl NaF MgCl2 CaCO3 N2 Cl2 Molecule or Compound? clip
16 Writing Chemical Formulas
17 • Writing chemical formulas is a shorthand way of indicating what a substance is made of. • These formulas also let you know how many atoms of each type are found in a molecule. The chemical formula for water is H2O. Carbon Dioxide is CO2. Why does oxygen combine in different ratios, in different compounds? The chemical formula for table salt is NaCl. Calcium Chloride is CaCl2. Why does chlorine combine in different ratios, in different compounds?
The simplest compounds are ones with only two elements These are called binary KI, CO, H2O, NaCl
Oxidation numbers +1 0 +4 -4 -2 +2 +3 -3 -1 Tell you how many electrons an atom must gain, lose or share to be come stable.
Oxidation numbers We can predict the ratio of atoms in ionic compounds based on their oxidation numbers +1 -1 1 valence electron K Cl 7 valence electron All compounds are neutral KCl Tells you how many electrons an atom must gain, lose or share to be come stable. That means the overall charge is ZERO!
+1 -1 +2 -1 Na Br Ca Br To make it ZERO, you need 1Ca and 2 Br. NaBr CaBr2 Subscripts show the number of atoms of that kind in the compound
Some elements have more than one oxidation number(Chart p588) +3 -2 +2 -2 Fe O Fe O Fe2O3 FeO We call these elements- Multivalent Elements
K + Br Mg + Cl Ca + I K + O K + I Sr + Br Na + O Ga + Br Fe+2 + O Fe+3 + O Cu+2 + F Cr+3 + O Mg + O Al + P Now You Try writing Binary Ionic formulas
Polyatomic Ions Groups of Covalently Bonded atoms that stay together.
Na + SO4 Mg + PO4 Ca + CO3 Na + OH Mg + OH NH4 + OH K + PO4 NH4 + NO3 H + SO4 Ca + SO4 K + NO3 Na + PO4 Try these…….
Naming Chemical Formulas
Naming Binary Compounds and Molecules • Steps: • If it is Binary- • Decide if it is an ionic or covalent bond. • Metal- nonmetal….. • Ionic • Nonmetal- nonmetal…. • Covalent
Check to see if any elements are multivalent. If all single valent, write the name of the positive ion first. Write the root of the negative ion and add –ide. Examples: NaCl K2O AlCl3 BaF2 KI Li2O If ionic …….
If ionic ……. Examples: • FeO • Fe2O3 • CuO • Cu2O • PbCl4 • PbI2 • Check to see if any elements are multivalent. • If multivalent ions, determine the oxidation number of the element. • Use Roman numerals in parentheses after the name of the element. • Write the root of the negative ion and add –ide.
Use Greek prefix to indicate how many atoms of each element are in the molecule Add -ide to the more electronegative element Greek Prefixes 1- mono- 2- di- 3- tri- 4- tetra- 5- penta- 6- hexa- 7- hepta- 8- octa- If Covalent... • Example: • NO • Nitrogen Oxide • PCl3 • Phosphorous trichloride
Write the name of the positive ion. Write the name of the polyatomic ion. Examples: NaCO3 KNO3 NaC2H3O2 If it contains a polyatomic ion... • Example: • KOH • Potassium Hydroxide • CaCO3 • Calcium Carbonate
KBr HCl MgO CaCl H2O NO2 CuSO4 CaSO4 NH4OH CaCO3 Cu(ClO3) 2 Cr2O 3 SrI 2 CCl4 Name the following:
34 Writing & Balancing Chemical Equations
35 Chemical Reactions • A chemical reaction is a change in which one or more substances are converted into new substances. • Rearrangement of bonds in compounds and molecules. • Chemical Equations make it possible to see clearly what is happen during a chemical reaction
36 Chemical equations are a shorthand way to show chemical reactions. Reactants Products H2 + O2 H2O
37 Conservation of Mass The mass of the products always equals the mass of the reactants
38 H2 + O2 H2O Does this meet the Conservation of Mass Law? 2 Hydrogen atoms 2 Oxygen atoms 2 Hydrogen atoms & one Oxygen atom Must Balance the Equation to show Conservation of Mass.
39 Can add coefficients to Balance equations. 2 H2 + O2 2 H2O 2 4 2 4 2 1 2 Balanced!! Steps: 1. Count Atoms on both sides 2. If not Balanced, add coefficients to balance. 3. Recount atoms after adding each coefficient. 4. Keep adding coefficients until balanced.
40 Types of Chemical Reactions
41 • Synthesis • Decomposition • Single Replacement • (Single Displacement) • Double Replacement(Double Displacement)
Synthesis “to make” A + B AB Cu + O CuO 2H2 + O2 2H2O
Decomposition “to breakdown” AB A +B 2H2O 2H2 +O2 NaOHNa+OH
Single Replacement When one element replaces another element in a compound A + BC AC + B Cu+AgNO3Cu(NO3)2+2Ag The more reactive metal will always replace the less reactive metal. (p749)
Single Replacement • Clip
Double Replacement Positive Ion of One compound replaces the positive ion of another compound and a Precipitate is formed. AB + CDAD+ CB Ba(NO3)2+K2SO4 BaSO4 2KNO3 Clip
Chemical Reactions and Energy
51 Chemical Reactions and Energy • All chemical reactions release or absorb energy. • Heat, light, sound • Chemical reactions are the making and breaking or bonds.
1. Exergonic • Chemical reactions that releases energy are called exergonic. • Glow sticks • If heat is released, it is called exothermic.