Chemistry Major Topics

Transcription

1 Chemistry Major Topics 1. Grade 9 Review 2. Periodic table 3. Electron dot diagrams 4. Ions 5. Bonding 6. Nomenclature 7. Chemical equations 8. Balancing chemical equations 9. Types of reactions 10. Acids and bases 1

2 Oxygen Atom Ions Oxygen Ion All metals electrons to become charged. They are called cations. All non metals electrons to become charged. They are called anions. Drawing Ionic Bonds: we use arrows to show the transfer of electrons 1. Draw Lewis dot diagrams for each atom. 2. Transfer electrons from metals to non metals until each atom involved has a full valence shell. 3. Draw the ions formed, including their charges. 4. Write the name/formula of the compound created. Lithium and Fluorine Calcium and chlorine 2

3 Covalent (Molecular) Compounds Covalent bonds form between 2 non metals Each of the non metals wants to gain electrons so neither will give up electrons in a transfer. Instead, atoms share one or more pairs of electrons in a covalent bond. Covalent bonds are weaker than ionic bonds. A neutral particle that is composed of atoms joined together by a covalent bond is called a molecule (often referred to as molecular compounds). Drawing covalent bonds: 1. We circle electrons to show that they are being shared between two atoms. No arrows are used because there is no transfer of electrons between atoms (and no ions are formed). 2. Replace the shared electrons with a line in a stick diagram. Any lone pairs (electrons not shared between atoms) must be drawn. 3. Write the name/formula of the compound created. iodine and iodine (I 2 ) I I OF oxygen and fluorine (OF 2 ) 3

4 Nomenclature Ionic Criss Cross Method metal nonmetal "ide" Covalent Prefix Method with NO criss crossing metal only has one charge Both charges come from periodic table metal can have more than one charge metal charge is in the name non metal charge from periodic table Polyatomic Ions Use chart on the back for names Put brackets around polyatomic ion for criss cross rule Write the NAME of the following compounds CaBr 2 Al 2 (SO 4 ) 3 Cu 2 O FeP 4

5 Write the FORMULA of the following compounds magnesium nitrate sodium sulphide lead (IV) chloride ammonium hydroxide Write the name of the following compounds N 2 O 5 Write the formula of the following compounds Phosphorus tetraiodide SO3 carbon monoxide H2O diphosphorus trioxide 5

6 We use equations to represent chemical reactions 2 Types: 1. Word Equations: potassium iodide + lead (II) nitrate potassium nitrate + lead (II) iodide 2. Chemical Equations: skeleton equation: KI + Pb(NO 3 ) 2 KNO 3 + PbI 2 Reactants "react to form" Products The law of conservation of mass states that the total mass of the reactants is always equal to the total mass of the products So... mass of reactants = mass of products Because of this law, we must balance chemical equations. The molecules are broken apart and the atoms are rearranged but we must ensure that there are equal numbers of atoms before and after the reaction. i.e. if I start with 5 hydrogen atoms, I must end with 5 hydrogen atoms. 6

7 Rules for balancing: 1. Balance all metals first 2. If possible, balance polyatomic ions as a "chunk" 3. Balance any non metals other that H and O 4. Balance Hydrogen 5. Balance Oxygen 6. Check both sides of the reaction to ensure all atoms are balanced! KI (aq) + Pb(NO 3 ) 2(aq) KNO 3(aq) + PbI 2(s) Al + H 2 SO 4 Al 2 (SO 4 ) 3 + H 2 C 3 H 8 + O 2 CO 2 + H 2 O Types of Reacons 1. Synthesis A + B > AB 2. Decomposion AB >A + B 3. Single Displacement AB + C > AC + B or AB + C > CB + A 4. Double Displacement AB + CD > AD + CB 5. Combustion Hydrocarbon + O2 --> CO2 + H2O 7

8 Acids and Bases An acid is a substance that produces hydrogen in solution, H + (aq). For example: i) When hydrochloric acid, HCl is placed in solution it dissociates into H + (aq) and Cl - (aq) ii) When sulfuric acid, H 2 SO 4 is placed in water it dissociates into H + (aq) and SO 4 2- A base is a substance that produces hydroxide in solution, OH - (aq). For example: i) When sodium hydroxide, NaOH is placed in solution it dissociates into Na + and OH - ii) When calcium hydroxide, Ca(OH) 2 is placed in solution it dissociates into Ca 2+ and OH - 8

9 Indicators Most solutions of acids or bases are liquid and clear. Therefore they cannot be distinguished from ordinary water by appearance alone. The simplest way to distinguish them from water is to use an indicator. An indicator is a substance that produces a colour change as the concentration of H + and OH - changes. Acids have a ph less than 7 Bases have a ph greater than 7 Neutral substances have a ph of 7 9

10 1. Br 2, F 2, and Cl 2 are all examples of: (a) mulvalent metals (b) molecular compounds (c) polyatomic ions (d) diatomic non metals 2. FeCl 3, LiBr, and Al 2 O 3 are all examples of: (a) ionic compounds (b) molecular compounds (c) polyatomic ions (d) diatomic molecules 10

11 3. What are the products in the reacon Mg(s) + 2HCl(aq) MgCl 2 (aq) + H 2 (g)? (a) Mg(s) and 2HCl(aq) (b) MgCl 2 (aq) and H 2 (g) (c) Mg(s) and MgCl 2 (aq) (d) 2HCl(aq) and H 2 (g) 4. Suppose a white solid with a mass of 20.0 g is heated. A chemical reacon happens. A brown solid and a gas are produced. Suppose the brown solid has a mass of 18.5 g. What would you predict the mass of the gas to be? (a) less than 18.5 g (b) exactly 18.5 g (c) = 38.5 g (d) = 1.5 g 11

12 5. A neutral soluon would have a ph of: (a) 1 (b) +1 (c) 8 (d) 7 6. A student tested an unknown soluon. She found that it turned blue litmus paper red, corroded metals, and conducted electricity. Using these properes, the unknown soluon is most likely: (a) basic (b) acidic (c) neutral (d) both acidic and basic 12

13 7. Which of the following is an example of a neutralizaon reacon? (a) 2HNO3(aq) + Ca(OH)2(s) Ca(NO3)2(aq) + 2H2O(l) (b) 6Ag(s) + Ca3(PO4)2(aq) 2Ag3PO4(aq) + 3Ca(s) (c) 2Mg(s) + O2(g) 2MgO(s) (d) Mg(OH)2(aq) + 2AgNO3(aq) Mg(NO3)2(aq) + 2AgOH(s) 8. Which of the following types of chemical reacon produces water and carbon dioxide gas? (a) combuson reacon (b) neutralizaon reacon (c) decomposion reacon (d) single displacement reacon 13

14 9. Idenfy the type of chemical reacon: 3Li 2 SO 4 + 2Al Al 2 (SO 4 ) 3 + 2Li. (a) combuson reacon (b) single displacement reacon (c) double displacement reacon (d) decomposion reacon 10. How do we indicate the charge on an ion of an element? (a) We write a number as a subscript on the right side of the chemical symbol to represent the charge. (b) We use a coefficient in front of the chemical symbol. (c) We place a posive or negave number above and to the le of the chemical symbol. (d) We place a posive or negave number above and to the right of the chemical symbol. 14

15 11. Which of the following is true of ionic compounds? (a) oppositely charged ions aract each other. (b) Electrons are shared between atoms. (c) Protons are transferred between atoms. (d) Protons are shared between atoms. 12. Which of the following is an example of a molecular compound? (a) SO 2 (b) CaS (c) Na 2 SO 4 (d) MgF 2 15

16 13. The number of valence electrons in an atom of calcium is: (a) 0 (b) 2 (c) 20 (d) The number of valence electrons in an ion of calcium is: (a) 0 (b) 2 (c) 20 (d) 3 16

17 14. The majority of the elements on the periodic table are: a) solid at room temperature b) metallic in nature c) reacve with other elements d) all of the above 17