Grade 10 Chemistry - 1st Quarter Examination (PDF)

A compound that contains only 2 elements. GRADE 10 - CHEMISTRY Binary ionic compounds use the ionic charges in First Quarter Examination order t...

A compound that contains only 2 elements. GRADE 10 - CHEMISTRY Binary ionic compounds use the ionic charges in First Quarter Examination order to write correct formulas Writing Correct Chemical Formulas for Binary Compounds: Topic 1: Naming And Writing of Binary Compounds 1. Determine the charge of each ion 2. Crisscross the value associated with the Compounds are a combination of at least charge to the bottom right of the other atom two elements that act as one unit. They have 3. Reduce the subscripts to the lowest possible separate identities different from their component terms elements. Topic 2: Naming of Ions When a compound forms it causes a chemical bond to occur. ATOMS AND IONS This is the force that holds two atoms Atoms are electrically neutral. together o Because there is the same number of protons (+) and electrons (-). This is the result when electrons are gained, Ions are atoms, or groups of atoms, with a lost, or shared between atoms charge (positive or negative) o They have different numbers of WHEN DO ATOMS GAIN OR LOSS ELECTRONS? protons and electrons. Only electrons can move, and ions are made Atoms gain electrons when they receive or by gaining or losing electrons. accept from another atom ANION They lose electrons when they donate to another atom A negative ion. Has gained electrons. Nonmetals can gain electrons. CHEMICAL FORMULAS Charge is written as a superscript on the right. Example Chemical formulas show the kinds and o F1- - has gained one exlectron (-ide is number of each atom present new ending = fluoride) The small numbers written below a symbol o O2- - gained two electrons (oxide) are called SUBSCRIPTS. Subscripts show the number of each atom present CATION Most compounds have metals are written A positive ion. first in the formula. Formed by losing electrons. More protons than electrons. Metals can lose electrons Binary Compounds Example  o K4+ has lost one electron (no name Examples: Tin (II) = Sn2+, Tin (IV) = Sn4+, Lead change for positive ions) (II) = Pb2+, Lead (IV) = Pb o Ca2+ has lost two electrons Group B elements: Some transition elements have only one possible oxidation state, such as these PREDICTING IONIC CHARGES three: Group 1A: lose 1 electron to form 1+ ions Silver = Ag1+, Zinc = Zn2+, Cadmium = Cd2+ Group 2A: loses 2 electrons to form 2+ ions Exceptions: Group 3A: loses 3 electrons to form 3+ ions Some of the transition metals have only one Group 4A: elements from this group rarely form ions ionic charge: Do not need to use roman numerals for Group 5A: gains 3 electrons to form 3- ions these: Group 6A: gains 3 electrons to form 2- ions o Silver is always 1+ (Ag1+) o Cadmium and Zinc are always 2+ Group 7A : gains 1 electron to form 1- ions (Cd2+ and Zn2+) Group 8A: stable noble gases do not form ions NAMING ANIONS Group B Elements: Many transition elements have Anions are always the same charge more than one possible oxidation state. Note the use Change the monatomic element ending to – of Roman numerals to show charges ide Example: Iron (III) = Fe 3+ F1- a Fluorine atom will become a Fluoride ion. NAMING OF CATIONS POLYATOMIC IONS 1. Stock System – uses roman numerals in parenthesis to indicate the numerical value Groups of atoms that stay together and have 2. Classical method – uses root word with an overall charge, and one name. suffixes (-ous, -ic) Usually end in –ate or -ite o Does not give true value Acetate: C2H3O21- We will use the Stock system. Nitrate: NO31- o Cation - if the charge is always the Nitrite: NO21- same (like in the Group A metals) just Permanganate: MnO41- write the name of the metal. Hydroxide: OH1- and Cyanide: CN1- o Transition metals can have more than KNOW COMMON POLYATOMIC IONS one type of charge. ▪ Indicate their charge as a Sulfate: SO42- roman numeral in parenthesis Sulfite: SO32- after the name of the metal Carbonate: CO32- (Use your Ion Sheet) Chromate: CrO42- Dichromate: Cr2O72- PREDICTING IONIC CHARGES Phosphate: PO43- Some of the post-transition elements also Phosphite: PO33- have more than one possible oxidation state.  Ammonium: NH41+ (One of the few positive Things to look for: polyatomic ions) 1. If cations have ( ), the number in parenthesis If the polyatomic ion begins with H, then is their charge. combine the word hydrogen with the other 2. If anions end in -ide they are probably off the polyatomic ion present: H1+ + CO32- periodic table (Monoatomic) → HCO31- 3. If anion ends in -ate or –ite, then it is hydrogen + carbonate → hydrogen polyatomic carbonate ion Topic 2: Naming and Writing Formulas for Ionic Compounds Topic 3: Naming and Writing Formulas for Molecular Compounds In naming ionic compounds, 1. Name the cation first, then anion 2. Monatomic cation = name of the element Molecular Compounds Ca2+ = calcium ion made of just nonmetals 3. Monatomic anion = root + -ide smallest piece is a molecule Cl- = chloride can’t be held together by opposite charge = CaCl2 = calcium chloride attraction In naming ionic compounds (Metals with multiple can’t use charges to figure out how many of oxidation states), each atom (there are no charges present) some metals can form more than one charge (usually the transition metals) Ionic compounds use charges to determine use a Roman numeral in their name: how many of each. PbCl2 – use the anion to find the charge on the cation (chloride is always 1-) o You have to figure out charges. Pb is the lead (II) cation 2+ o May need to criss-cross numbers. PbCl2 = lead (II) chloride Molecular compounds: the name tells you Example: Barium nitrate (note the 2 word name) the number of atoms. 1. Write the formulas for the cation and anion, o Uses prefixes to tell you the exact including CHARGES! number of each element present! 2. Check to see if charges are balanced. 3. Balance charges , if necessary, using PREFIXES subscripts. Use parentheses if you need 1 = mono- 6 = hexa- more than one of a polyatomic ion. Use the 2 = di- 7 = hepta- criss-cross method to balance subscripts. 3 = tri- 8 = octa- 4 = tetra- 9 = nona- 5 = penta- 10 = deca- To write the name, write two words: Prefix and Name, Prefix and Name (-ide)  One exception is we don’t write mono if there is only one of the first element. Normally, we do not have double vowels when writing names (oa oo) Topic 4: Naming and Writing Formulas for Acids and Bases Acids are Compounds that give off hydrogen ions (H1+) 2 additional rules when dissolved in water (the Arrhenius definition) 4) If the acid has 1 more oxygen than the –ic acid, Will start the formula with H. add the prefix per- There will always be some Hydrogen next to a. HClO3 (Hydrogen Chlorate) is chloric an anion. acid The anion determines the name. b. HClO4 would be perchloric acid 5) If there is 1 less oxygen than the -ous acid, RULES FOR NAMING ACIDS: add the prefix hypo- 1) If the anion attached to hydrogen ends in - a. HClO2 (Hydrogen Chlorite) is ide, put the prefix hydro- and change -ide to chlorous acid, then HClO would be -ic acid hypochlorous acid HCl - hydrogen ion and chloride ion = hydrochloric acid Writing Acid Formulas – in reverse! H2S hydrogen ion and sulfide ion = hydrosulfuric acid Hydrogen will be listed first If the anion has oxygen in it, then it The name will tell you the anion ends in -ate or -ite Be sure the charges cancel out. 2) change the suffix -ate to -ic acid (use no Starts with prefix hydro?- there is no oxygen, prefix) -ide ending for anion Example: HNO3 Hydrogen and nitrate no prefix hydro? ions = Nitric acid 1) -ate anion comes from –ic ending 3) change the suffix -ite to -ous acid (use no prefix) 2) -ite anion comes from –ous ending Example: HNO2 Hydrogen and nitrite A base is an ionic compound that produces ions = Nitrous acid hydroxide ions (OH1-) when dissolved in water (the Arrhenius definition) Bases are named the same way as other ionic compounds:  The name of the cation (which is a metal) is Oxyanions are binary anions in which one followed by the name of the anion (which will element is oxygen. When a non-metal forms be hydroxide). two different oxyions, the suffix –ate is used containing the large number of oxygen Topic 5: The Laws Governing Formulas and atoms, and the suffix –ite is used to the Names smaller number of oxygen atoms. 1. Law of Definite Proportions- in a sample of a chemical compound, the masses of the o Examples: elements are always in the same proportions. o NO2- (nitrite), SO32- (sulfite), PO33- a. H2O (water) and H2O2 (hydrogen (phosphite) peroxide) o NO3- (nitrate), SO42- (sulfate), PO43- 2. Law of Multiple Proportions- Dalton stated (phosphate) that whenever two elements form more than For elements that form more than two one compound, the different masses of one oxyanions, such as chlorine, the prefix –per is element that combine with the same mass of used for largest number of oxygen atoms the other element are in the ratio of small and –hypo for smaller number of oxygen whole numbers. atoms. o Examples: o ClO42- perchlorate HELPFUL TO REMEMBER: o MnO4- permanganate o ClO32- chlorate 1. In an ionic compound, the net ionic charge is o ClO22- chlorite zero (criss-cross method) o ClO- hypochlorite 2. An -ide ending generally indicates a binary Oxyanions that contain acidic hydrogens are compound named with the word hydrogen. An older 3. An -ite or -ate ending means there is a method involves the use of prefix bi- for polyatomic ion that has oxygen oxyanions containing only one hydrogen. 4. Prefixes generally mean molecular; they o Examples: show the number of each atom o HCO3- hydrogen carbonate or 5. A Roman numeral after the name of a cation simply bicarbonate is the ionic charge of the cation o HSO4- hydrogen sulfate or simply bisulfate o HPO42- hydrogen phosphate or TOPIC 6: TERNARY COMPOUNDS simply biphosphate Ternary compounds are compounds containing o H2PO4- dihydrogen phosphate (use three or more elements. of bi- does not apply because there will be two prefixes) Ionic Compounds o A few polyatomic anions are named NAMING OF COMPOUNDS with an –ide suffix. An ionic compound is named by giving the o Examples: OH- (hydroxide) CN- name of the cation first followed by the name of the (cyanide) O22-(peroxide) anion. Examples: Naming of Bases K2SO4 potassium sulfate Bases contain the hydroxyl group –OH in combination with a metal ion. Name the metal ion K2HPO4 potassium biphosphate followed by the word hydroxide. Ca (NO3)2 calcium nitrate Examples: Mg (NO3)2 magnesium nitrate NaOH - sodium hydroxide KH2PO4 potassium dihydrogen phosphate Ba (OH) - barium hydroxide Cr2 (SO4)3 chromium (III) sulfate Cu (OH)3 - copper (III) hydroxide or cupric hydroxide NAMING OF HYDRATES A hydrate is a substance that contains water Topic 7: Types of Chemical Reactions molecules as part of its crystalline structure. PARTS OF A CHEMICAL EQUATION Hydrates are named by indicating the name of the compound first exclusive of the water followed by 𝐵𝑎2 (𝑁𝑂3−1 )2 + 𝑁𝑎+1 𝐶𝑙−1 → 𝐵𝑎2 𝐶𝑙2−1 + 𝑁𝑎1 𝑁𝑂3−1 the name –hydrate with a prefix (number) 𝑩𝒂𝟐 (𝑵𝑶−𝟏 𝟑 )𝟐 + Reactant representing the number of water molecules +𝟏 −𝟏 𝑵𝒂 𝑪𝒍 → - Always left part of present. 2 −1 𝐵𝑎 𝐶𝑙2 + the equation Examples: 𝑁𝑎1 𝑁𝑂3−1 - Substances that are destroyed by the BaCl2 ∙ 2H2O barium chloride dihydrate chemical change (bonds CuSO4 ∙ 5H2O copper sulfate pentahydrate break). Sr (NO3)2 ∙ 6H2O strontium nitrate hexahydrate 𝐵𝑎𝟐 (𝑁𝑂𝟑−𝟏 )2 + Oxidation Number 𝑁𝑎+𝟏 𝐶𝑙−𝟏 → - Is the number of 𝐵𝑎𝟐 𝐶𝑙𝟐−𝟏 + electrons an atom/ion NAMING OF ACIDS 𝑁𝑎𝟏 𝑁𝑂𝟑−𝟏 that the molecule has If the oxyanion’s name ends in –ite, the suffix –ous is either gained or lost. attached to the root of the anion name. If the name 𝐵𝑎𝟐 𝐶𝑙2−𝟏 + Product of the oxyanion ends in –ate, the suffix –ic is 𝑁𝑎𝟏 𝑁𝑂3−𝟏 - Always found at the attached to the root of the anion name. right part of the equation Examples: - Substances created by the chemical change H2CO3 carbonic acid (from CO32- carbonate) (new bonds form). HNO3 nitric acid (from NO3- nitrate) 𝐵𝑎2 (𝑁𝑂𝟑−1 )𝟐 + Subscript Number 𝑁𝑎+1 𝐶𝑙−1 → HNO2 nitrous acid (from NO2- nitrite) 𝐵𝑎2 𝐶𝑙𝟐−1 + 𝑁𝑎1 𝑁𝑂𝟑−1 H2SO4 sulfuric acid (from SO42- sulfate) → Yields H2SO3 sulfurous acid (from SO 3 2- sulfite)  - “yields to / which 2. Decomposition (AB → A + B) reactions yealds to” are the opposite of synthesis reactions. In a - Equivalent to decomposition reaction, a complex “equals to” in a substance breaks down into two or more mathematical equation. simpler substances. For example, water can - It separates the decompose into hydrogen and oxygen reactant from the (2H2O → 2H2 + O2). products through a certain process. Decomposition of a compound produces OTHER ELEMENTS IN AN EQUATION two or more elements and/or compounds. The products are always simpler than the COEFFICIENTS - Numbers precatoms or reactant. Gases are often produced (H2, N2, molecules of the substance are involved in O2, CO2, etc.) in the decomposition of the reaction. Ending the chemical formulae. covalent compounds. Ionic compounds may It shows how many be decomposed into pure elements by using The other symbols that are included in a electricity (electrolysis). This is how pure chemical reaction are as follows: metals are obtained from salts. (s)= solid, (l)= liquid, (aq)= aqueous solution / the substance is dissolved in H2O TYPES OF DECOMPOSITION REACTION “+” = separates two or more reactants or When oxides are heated, generally, product oxygen is given off as one of the product. TYPES OF CHEMICAL REACTIONS Example: 2HgO(s) → Hg(s) + 1. Synthesis reactions (A + B → AB) are also O2(g) known as combination reactions. In a Some carbonates when heated synthesis reaction, two or more simple decompose to yield carbon dioxide. substances combine to form a more complex substance. For example, hydrogen Example: CaCO3 (s) → CaO and oxygen combine to form water (2H2 + + CO2 O2 → 2H2O). Hydrogen carbonates or bicarbonates TYPES OF SYNTHESIS ARE: when heated yield carbon dioxide, water and a carbonate salt. Metal + nonmetal → Binary salt Example: 2NaHCO3 (s) → Na2CO3 + Ex: Na(s) + Cl (g) → 2NaCl(s) H20 (g) + CO2 (g) 2 Hydrates are substances that contain Metal + Oxygen → Metal oxide one or more molecules of water for each formula unit. These compounds, upon Ex: 4Al(s) + 3O (g) → 2Al O (g) application of heat, readily decompose. The 2 2 3 water is driven off, leaving the anhydrous Metal oxide + Water → Metal hydroxide (without water) salt. Ex: CaO(s) + H O(l) → Ca(OH) (s) Example: CuSO4. 5H2O → 2 2 CuSO4 + 5H2O  3. Single replacement reactions (A + BC → Ex: 2HCl (aq) + Mg(OH)2(s) → MgCl2(aq) AC + B) involve one element replacing + 2 H2O(l) another element in a compound. For 5. Combustion ( CxHy + O2 → CO2 + H2O) example, Zn + CuSO4 → ZnSO4 + Cu. reactions are reactions that involve the Do all single replacement reactions actually burning of a substance in oxygen. The occur? Not necessarily! How do we know products of a combustion reaction are which reactions will occur and which ones will always carbon dioxide and water. Example: not? CH4 + 2O2 → CO2 + 2H2O o We look at the activity series. 6. Acid-base neutralization (HA + BOH → Elements with higher activities BA + H2O) reactions occur when an acid replace elements with lower and a base react to form a salt and water. activities during a single- The products of an acid-base neutralization replacement reaction, but not vice- reaction are always a salt and water versa. (Example: HCl + NaOH → NaCl + H2O). 4. Double replacement (AB + CD → AD + CB) reactions involve two elements Here are some additional examples of each type switching places in two different of chemical reaction: compounds. For example, NaCl + AgNO3 → Synthesis reactions: NaNO3 + AgCl o Magnesium + oxygen -> magnesium TYPES OF DOUBLE REPLACEMENT: oxide A salt and a base o Nitrogen + hydrogen -> ammonia Ex: Ca(NO3)2 (aq) + 2NaOH (aq) → Ca(OH)2 o Carbon + oxygen -> carbon dioxide (aq) + NaNO3 (aq) Decomposition reactions: Two salts (binary + binary; or binary + ternary ; or ternary + ternary) o Water -> hydrogen + oxygen Ex: 2KCl (aq) + Pb(NO3)2 (aq) → PbCl2 (s) + o Hydrogen peroxide -> water + 2KNO3 (aq) oxygen A salt and an acid o Calcium carbonate -> calcium oxide + carbon dioxide Ex: Ba(NO3)2(aq) + H2SO4(aq) → BaSO4(aq) + 2HNO3(aq) Single replacement reactions: Metal carbonate and an acid o Zinc + copper sulfate -> zinc sulfate + copper Ex: MgCO3(s) + 2HCl(aq) → MgCl2(aq) + H2O(l) + CO2(g) o Iron + copper chloride -> iron chloride + copper o Sodium + water -> sodium hydroxide An acid and a base (also known as + hydrogen neutralization reaction) Double replacement reactions:  o Sodium chloride + silver nitrate -> Topic 8: Evidences of Chemical Reactions sodium nitrate + silver chloride Chemical Reaction is a process in which one o Potassium iodide + lead nitrate -> or more substances, also called reactants, are potassium nitrate + lead iodide converted to one or more different substances, known as products. o Calcium chloride + sodium carbonate -> calcium carbonate + sodium PHYSICAL CHANGE CHEMICAL CHANGE chloride A change which does A change that involves not produce a new kind the transformation of Combustion reactions: of substance but simply materials into another o Methane + oxygen -> carbon dioxide results in another form kind of substance. + water of the same substance o Propane + oxygen -> carbon dioxide is called a physical + water change. o Ethanol + oxygen -> carbon dioxide + water EVIDENCES: Acid-base neutralization reactions: 1. Glass Bubbles Appear Gas bubbles appear after a chemical o Hydrochloric acid + sodium reaction has occurred and the mixture hydroxide -> sodium chloride + water becomes saturates with gas. The chemical o Sulfuric acid + potassium hydroxide - change that creates the gas is completed > potassium sulfate + water after the bubbles leave the mixture. Examples: the antacid that is dropped in a o Nitric acid + ammonium hydroxide -> glass of water and begins to bubble ammonium nitrate + water 2. Formation of Precipitation Diatomic molecules are molecules that A precipitate is a white solid formed when consist of two atoms of the same element bonded two liquids are combined and then react. It is together. Examples of diatomic molecules include a different substance to either of the H2, O2, N2, Cl2, Br2, and I2. reactants and does not dissolve in the reaction mixture. It may either sink to the Ionic compounds are compounds that are bottom or remain suspended within the formed when a metal atom donates an electron to a solution and this makes the mixture cloudy. nonmetal atom. The resulting ions are attracted to 3. Energy Change each other by electrostatic forces. a. TEMPERATURE: Chemical reactions that Acids are substances that donate hydrogen tend to bond-breaking tend to absorb energy ions (H+) in solution. Bases are substances that from the surroundings, making the accept hydrogen ions (H+) in solution. surroundings cooler. Chemical reactions that involve making bonds release energy which Salts are ionic compounds that are formed makes the surrounding hotter. The best when an acid and a base react. example is when a burning fire produces heat. b. PRODUCTION OF LIGHT : When energy is released due to a chemical change, it  sometimes creates a light source. This type of reactions tends to occur in combustions such as fire of burning process. c. PRODUCTION OF SOUND: Cracker on ignition produces sound due to the sudden formation of a large amount of gas due to chemical reactions, such a reaction is called an explosion. 4. Formation of Gas A gas can be formed when two liquids are combined, or when a solid is combined to a liquid. The formation of bubbles when two liquids or a solid and liquid are mixed usually indicates that a gas has formed. 5. Color Change Color changes are commonplace when substances are combined, but one of the identifying factors of a chemical reaction is an unexpected color change. 6. Change in Smell or Taste Each chemical reaction has a distinct smell or taste. When the compound changes after the chemical reaction, the taste or smell changes as well. 7. Formation of New Substances Everything that has been presented previously is due to the present of a catalyst, a substance that speeds up chemical. There must a reaction before a new material will be produced. If there is a chemical reaction between substances involved, expect for a new material to be produced. This material does not anymore possess the characteristics of either of the substances before the reaction.