UNIT REVIEW:

 Chemicals & Their Properties  Chemicals & Their Reactions  Acids & Bases

 Chemical Periods and Groups  Row – period  Column – group  4 best known groups ▪ Group 1: Alkali Metals ▪ Group 2: Alkaline Earth Metals ▪ Group 17: Halogens ▪ Group 18: Noble Gases

 Proton  Positive charge, located in nucleus  Neutron  Neutral, located in nucleus  Electron  Negative charge, orbit around nucleus

 Electron orbit shown as ring around nucleus  1 st orbit – 2 electrons  2 nd & 3 rd orbit – can old maximum of 8 electrons  Example: Sodium

 An ion is an atom that has become charged by gaining or losing electrons  Positive ion - cation  Negative ion - anion

 Ionic Compound  A compound made up of one or more positive metal ions (cations) and one or more negative non-metal ions (anions)  Example: sodium chloride

 Made up of 2 elements: metal and non-metal  Keep name of metal, change end of non- metal to “ide”  Writing compounds: criss-cross rule  Examples:  Magnesium chloride  Aluminum oxide

 Copper (I) or Copper (II)  Iron (II) or Iron (III)  Lead (II) or Lead (IV)  Maganese (II) or Maganese (IV)  Tin (II) or Tin (IV) *PRACTICE Page 200 #9

 An ion made up of more than one atom that acts as a single particle  Page Table 1: Formulas and Names of Common Polyatomic Ions  Examples:  Sodium carbonate  Iron (III) nitrate  Ca(OH) 2 *PRACTICE Page 205 #1,2

 Molecular compound - a pure substance formed by two or more non-metals  Covalent bond - a bond that results from atoms sharing electrons  Diatomic molecules - molecule consisting of only 2 atoms of either the same or different elements  Table 1 Page 208 Common Diatomic Molecules  HOFBrINCl  Table 2 Page 298 Common molecular compounds

 Mon(o)- = 1  Di- = 2  Tri- = 3  Tetra- = 4  Penta- = 5 *PRACTICE Page 212 #3 (Ionic or molecular?)

 Word equations - writing names of products and reactants  Chemical equations - using chemical formulas of products and reactants  Reactant - a chemical, present at the start of a chemical reaction that is used up during a reaction  Product - a chemical that is produced during a chemical reaction  State symbols in chemical reactions: (s) solid, (l) liquid, (g) gas, (aq) aqueous - dissolved in water

 Law of conservation of mass - in any given chemical reaction, the total mass of the reactants equals the total mass of the products  Chemical equations obey the law of conservation of mass - the number of atoms of reactants are still present in the products  Coefficients are added before chemical formulas in a chemical equation to ensure the number of atoms on each side of arrow are equal (balanced)

 Step 1: Word equation  Step 2: Replace each chemical name with the correct chemical formula  Step 3: Count the number of atoms of each type on either side of the arrow  Step 4: Multiply the formulas by an appropriate coefficient until all the atoms are balanced. Keep checking whether the numbers of each type of atom on both sides are balanced.  NOTE: Because polyatomic ions generally stay intact, you can count polyatomic ions in the same way you count atoms  Step 5: The balanced chemical equation *PRACTICE Page 236 #5, 7

 SYNTHESIS REACTIONS  Two simple reactants combine to make a larger or more complex product  General pattern: A + B → AB  DECOMPOSITION REACTIONS  Reaction in which a large or more complex molecule breaks down to form two (or more) simpler products  General pattern: AB → A + B

 SINGLE DISPLACEMENT REACTIONS  A reaction in which an element displaces another element in a compound, producing a new compound and a new element  General equation A + BC → AB + C  DOUBLE DISPLACEMENT REACTIONS  A reaction that occurs when elements in different compounds displace each other or exchange places, producing two new compounds  General equation AB + CD → AD + CB

 COMBUSTION  Complete combustion: hydrocarbon + oxygen → carbon dioxide + water + energy  Incomplete combustion also produces carbon monoxide and soot  Other combustion reactions: element + oxygen → oxide + energy  CORROSION  The breakdown of metal as a result of chemical reactions with the environment  Rust - corrosion of metals containing iron  Causes of rust - oxygen, water, electrolytes  Preventing corrosion - protective coatings, corrosion resistant materials, galvanizing

*PRACTICE Page 258 # 7

 Properties of Acids  Acids - an aqueous solution that conducts electricity, tastes sour, turns litmus red and neutralizes bases  Molecular compounds - become ions in water - conduct electricity (H+ ions)  Chemical formulas of acids - begin with H and end with (aq)  Names of acids ▪ Binary acids - only contain 2 elements (Table 1 Page 269) ▪ Oxyacids - related to polyatomic ions (Table 2 Page 269)

 Properties of Bases  Bases - aqueous solution that conducts electricity, tastes bitter, and turns litmus blue  Electrolytes - form ions when dissolved in water  Names and Formulas of Bases (Table 4 Page 271)  Acid-base indicator  A substance that changes color depending on whether it is in an acid or a base ▪ Table 3 Page Bromo blue, Phenophthalein, Litmus

 pH is a measure of how acidic or basic a solution is  pH scale is a numerical scale of all the possible numerical values of pH from 0-14 used to compare the acidity of solutions  Neutral - neither acidic or basic, with pH of 7  Solution with pH less than 7 considered acidic  Solution with pH greater than 7 considered basic

 Occur when an acid and a base react to form products with pH closer to 7 than either of the reactants  Products are an ionic compound (sometimes called a “salt”) and water  Acid + Base → Water + Ionic Compound  Applications:  Chemical Spills  Antacids

 Acid precipitation - term used to describe any precipitation (rain, snow, fog) that has become acidic from reacting with compounds in atmosphere  Pollutants - sulfur oxides and nitrogen oxides - combine with water in atmosphere  Acid rain has pH less than 5.6 (normal rain)  Source of pollutants - Combustion of fossil fuels  Environmental Impact of Acid Precipitation  Aquatic Ecosystems, Soils, Forests  Economic Impact  Damage to structures, buildings, and monuments