Unit 2- Chemistry Chapter 5 and 6 Read Page 165 Feb 20 11:16 AM Chemistry is the study of Matter, its properties, and its changes or transformations. Matter is anything that has mass and takes up space. All types of matter have physical and chemical properties. H H H C H O H O C O H Nov 12 12:48 PM 1
Classify the following as Matter or Non matter May 23 6:27 PM CHEMISTRY IS ALL AROUND US!! Combustion (burning) of candle wax C 25 H 52 + 38O 2 > 25CO 2 + 26H 2 O Rust on your or your parents car (oxidation of iron) Reaction of iron and oxygen in the presence of water or air moisture Driving a car Burning chemicals to produce energy Cooking in the kitchen Mixing different types and amounts of matter together Toothpaste sodium fluoride in toothpaste reacts with your mouth to rebuild enamel and control bacteria Soap and shampoo has sodium or potassium which clean dirt and oils off your body Chlorine keeps bacteria and algae populations under control in pool water Nov 12 12:49 PM 2
5.1 Chemicals and Chemical Change ( Pgs 172 174) Matter is classified as being a pure substance or being a mixture. A pure substance is one in which all of the particles that make up that substance are the same. Pure substances are classified as either : Elements or Compounds. Elements are pure substances that cannot be broken down into simpler substances. Below, draw a flow chart showing the basic organization of matter: (See figure 2, pg. 172) Nov 12 2:35 PM 1. Pure Substances: A) Elements: can be identified with a chemical symbol E.g.=s: Au, Fe are listed on the periodic table There are more than 100 known elements!! can exist naturally as pairs (when 2 or more atoms join together) They are called diatomic elements! E.g. H 2, N 2, O 2, F 2, Cl 2, Br 2, I 2 B) Compounds: contain two or more different elements in a fixed proportion. can be identified with chemical formulas, which indicate the element(s) present and the number of atoms. 3 E.g.=s: CO 2, H 2 O and CO Nov 12 2:41 PM 3
2. Mixtures Contain 2 or more pure substances and can be classified as Homogeneous Mixtures or Heterogeneous Mixtures Homogenous Mixtures or Solutions Have only one visible component. Heterogeneous mixtures have two or more visible components Feb 20 10:57 AM Properties of Matter All matter has physical and chemical properties. Physical Properties A physical property is a characteristic of a substance that can be sensed/described or measured. Some physical properties include: A) State of matter (solid, liquid or gas) B) Hardness C) Melting Point D) Boiling Point E) Odour F) Solubility (how easily it dissolves) G) Colour H) Magnetic I) DENSITY A change in the size or form of a substance, which does not change the chemical properties of a substance is called a physical change. Nov 12 2:51 PM 4
Chemical Properties A chemical property is a characteristic behaviour that occurs when a substance changes to a new substance with new and different properties. This reaction is called a chemical change. Clues that a chemical change has occurred: A) Colour change (alone, does not prove that a chemical change has occurred must be with other properties) B) Energy change (heat or light is given off) C) Gas produced (Bubbles or gas form) D) Precipitate forms (solid forms in a liquid/ gets cloudy) E) Change is difficult to reverse An example of a chemical change is: baking soda and vinegar. The starting materials in a chemical change are called reactants and the new materials produced are called products. A chemical change can be written as a chemical reaction: Reactant + Reactant Products 2H 2 + O 2 2H 2 O Chemists can use the properties of chemicals and chemical tests to identify unknown substances. Fill out the following chart on indication of gas formation: Nov 12 2:57 PM Oct 8 1:52 PM 5
Nov 12 3:05 PM Classifying Matter Mixtures Pure Substances Heterogeneous Mixture Different throughout Homogeneous Mixture The same throughout Compound 2 or more elements chemically combined Element One type of element present Mar 19 7:45 AM 6
Classify the Following Substances as Elements, Compounds, and Mixtures May 23 8:08 PM Your Task: Worksheet Page 175 # 1 2, 4 8 Nov 12 3:22 PM 7
5.5 Elements and the Periodic Table All known elements are organized into the periodic table. Combinations of these elements make compounds An elements position on the periodic table is characteristic of the element Metals are found on the left hand side of the table Non metals are found on the right hand side of the periodic table Nov 12 3:49 PM Table 1 (Page 185) Properties of Metals and Nonmetals Nov 12 3:51 PM 8
Periods Horizontal rows on the periodic table are called period Each period represents an electron shell or orbit Nov 12 3:53 PM Chemical Families/ Groups Vertical columns on the periodic table Families include elements with similar chemical and physical properties (E.g. Group 1 shiny silvery metals), atomic structure (same number of valance electrons in the outermost shell) and reactivity Nov 12 3:51 PM 9
Other classifications 1. Metals, Nonmetals, and Metalloids 2. Representative elements, transition elements and inner transition metals Representative elements A Groups or main group (1 st two families and last six families. Transition elements B groups families 3 12 (many of these elements have more than one ionic charge) Inner transition metals part of periods 6 and 7 made of the lanthanide series and the actinide series 3. Four common chemical groups Nov 12 3:53 PM Four common chemical groups A. Alkali metals (Group IA) Shiny, silvery metals. They react violently with water Assume an ionic charge of +1 when forming compounds B. Alkaline earth metals : (Group IIA) Also shiny silvery metals that react less violently with water Assume an ionic charge of +2 C. Halogens: Group 17 (VIIA) Non metals that are poisonous elements Ionic charge 1 Make many compounds with groups 1 and 2 2 solids, 1 liquid and 2 gases at room temperature D. Noble Gases: Group 18 (VIIIA) All very stable Formerly called inert gases because of their resistance to make chemical compounds Nov 12 3:55 PM 10
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Jun 18 9:56 AM BrainPop Movies (click on the stars to visit the site for that subject) Compounds and Mixtures Atoms Periodic Table States of Matter Nov 25 4:43 PM 13
ATOMIC STRUCTURE The Bohr Rutherford model suggests that atoms are composed of 3 types of subatomic particles: protons, neutrons and electrons The diagram represent the arrangement of electrons in various orbits Nov 16 10:06 AM Proton heavy positively charged particles that are found in a dense positive core of the atom called the nucleus # of protons = atomic number Neutron neutral particles that have about the same mass as protons and are also found in the nucleus # of neutrons = mass number atomic number Electron negatively charged particles with almost no mass and are found in the orbit/shells of the atom # of electrons = number of protons (When the atom is neutral) Nov 12 4:04 PM 14
Valence Shell The outermost level that electrons occupy (the shell involved in bonding) Valence electrons The electrons contained in the outermost energy level Isotopes atoms of the same element with different mass numbers due to a different number of neutrons. Atomic Mass average of all isotopes of an element Nov 16 10:16 AM Bohr Diagrams show how electrons are arranged and how this can affect bonding. 1 st orbit can have max of 2 electrons 2 nd orbit can have no more than 8 electrons 3 rd orbit can have no more than 8 electrons 13p + 14n Al 3e 8e 2e How you may have drawn these previously. How you will draw them this year. Nov 16 10:08 AM 15
Electron Arrangements: The farther away an electron is from the nucleus, the greater its energy and the more likely it will be involved in a chemical change. Thus, the electrons in the outer orbital are involved in bonding. Bohr diagrams can be used to represent the arrangement of electrons in each orbital. Feb 24 8:33 AM Noble Gases: This group of elements are stable. From the information given in Figure 6, state why each of the examples are considered stable: Because they have a full valence shell. Other elements are not stable in order to become stable either lose or gain electrons. This is to allow them to have the stable electron configuration of the closest noble gas. Feb 24 8:35 AM 16
BrainPop Movies (click on the stars to visit the site for that subject) Atomic Model Isotopes Periodic Table Nov 25 4:43 PM Your TASK: Atomic Structure Worksheet Nov 17 10:54 AM 17
1. a. Everything around us is made up of Atoms/Elements A group of these things are called Molecules/Compounds b. An atom is mainly composed of: Protons which has a positive charge Electrons which has a negative charge, and Neutrons which has a neutral charge 2. a. Are the atoms for hydrogen and oxygen identical? NO b. Are the atoms for hydrogen identical? YES 3. Protons and Neutrons are found in the nucleus. 4. Protons and Neutrons have approximately the same mass while Electrons are the lightest of all three. Therefore, most of the mass of an atom is contained in its Nucleus Nov 17 10:55 AM 5. a. The atomic number is the number of Protons b. The mass number is the number of Protons and Neutrons c. Which one identifies the elements on the periodic table? Atomic # 6. a. The element carbon is atomic number 6. This means it has 6 protons and 6 electrons. b. An element has 47 protons. How many electrons does it have? 47 What is the element? Silver What is its symbol? Ag Nov 17 11:09 AM 18
7. 8. The element with one more proton than carbon is Nitrogen Nov 17 11:10 AM 9. Nov 17 11:11 AM 19
10. Draw the following atoms to show the number of electrons in each of their energy levels (orbits). Also write the electron energy levels using the bracket notation. a) carbon b) oxygen c) neon d) chlorine e) argon f) fluorine 11. Name three elements whose atoms have full outer energy level. a. Helium b. Neon c. Argon 12. Name three elements whose atoms have only one electron in their outer energy level. a. Sodium b. Lithium c. Potassium Nov 17 11:11 AM Electron Dot Diagrams or Lewis Dot Diagrams Lewis Dot Structures used to show how many valence electrons an element has. This information is known based on the elements position on the periodic table. Nov 16 10:16 AM 20
Be Al B Be Br Al C N Ca Cl F Ga H I Mg N Na O Sr Nov 22 5:44 PM Mar 1 9:28 AM 21
Ion charged atom in which the number of electrons is different from the number of protons due to a loss or gain of electrons Positive ions are called cations Negative ions are called anions Ionic Charge numerical value of the electric charge with a + or. Formed by the difference between the number of protons and electrons Examples: Al 3+, F 1,S 2 Note: When nonmetals gain electrons to form ions the name of the ion changes its ending to ide (E.g. F ion is called a fluoride ion) Nov 16 10:14 AM Atoms and Ions Atoms by themselves are neutral (have no charge). The number of PROTONS (+) equals the number of ELECTRONS ( ) so they are balanced. However, in forming a chemical compound an atom of an element can GAIN or LOSE one or more electrons. The number of electrons is no longer equal to the number of protons, then an atom becomes an ION. An ION is an atom or group of atoms that have a POSITIVE or NEGATIVE charge. More specifically: A CATION is an atom or group of atoms with a positive charge. They have LOST one or more electrons. They are usually METALS. An ANION is an atom or group of atoms with a NEGATIVE charge. They GAIN one or more electrons. They are usually NON METALS and the names of anions of non metallic elements change the name and end in ide. Oct 26 3:34 PM 22
Examples: 1. Ca is a calcium atom. Ca 2+ is a CALCIUM ion (cation). It LOST 2 electrons. The ending of the name stays the same with cations! 2. I is an iodine atom. I 1 is an iodide ion (anion). Iodine gained 1 ELECTRON. The ending changes with anions! Group 1 elements The ALKALI METALS have one electron in its outermost shell. Each element will become more stable by LOSING its single outermost electron. It is then left with a filled shell and becomes a positive ion (cation) with a charge of +1. Very little energy is required to move the outermost electron therefore the alkali metals are very reactive. Group 2 elements the ALKALINE EARTH METALS become more stable when they give up 2 electrons in their outermost ring giving it a 2+ charge. Beryllium then becomes beryllium ion or Be 2+ Group 13 elements will give up 3 electrons to become a cation with a 3+ charge. Oct 26 3:35 PM Group 14 elements do not normally form ions as they either need to GAIN 4 electrons or LOSE 4 electrons. Group 15 elements have 5 valence electrons which means they have 3 spaces in the outermost ring for electrons. When their outer ring is full they have three extra electrons (gain 3 electrons) therefore they have a charge of 3. Group 16 elements have 6 valence electrons therefore will need to GAIN 2 electrons to become stable which gives these anions a 2 charge. Group 17 elements The HALOGENS are highly reactive. This is because each halogen atom has 7 electrons in its outermost shell (valence shell). By GAINING 1 electron, each halogen atom can fill its outermost shell, becoming more stable. When a fluorine atom gains an electron, it is called fluoride ion (F 1 ), with 8 electrons in its outermost shell and has a charge of 1. Oct 26 3:33 PM 23
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Complete the chart using a periodic table to help you. ion symbol Nov 30 4:46 PM Your Task: Complete the ION Worksheet Complete Questions 1 8 on page 187 Oct 27 2:55 PM 25
8. Answer all questions on page 187. 1. Set up a chart to compare metals and nonmetal with respect to the following: Nov 21 8:13 PM 2. What element is located in the metallic area of the periodic table, but has mainly nonmetallic properties? Hydrogen is usually found in the metallic area of the Periodic Table, bus has mainly nonmetallic properties. 3. How many electrons are found in each of the first three orbits for the first twenty elements? Orbit 1 = up to 2 electrons Orbit 2 = up to 8 electrons Orbit 3 = up to 8 electrons Nov 21 8:13 PM 26
4. Draw Bohr diagrams for the following: a) Boron atom Nov 21 8:13 PM b) Chlorine atom c) Nitrogen atom d) Beryllium atom Nov 21 8:13 PM 27
5. What kind of arrangement of electrons in the outer orbit does a stable ion have? The outer orbit of a stable ion has a full outer orbit of electrons ( has an octet of e ). Helium is full with only 2 e. Nov 21 8:13 PM 6. a) Draw Bohr diagrams for the stable ion formed by each of the atoms in question 4. B 3+ Cl N 3 Be 2+ Nov 21 8:13 PM 28
b) State the number of electrons gained or lost to form each ion. Boron = loses 3 e Chlorine = gains 1 e Nitrogen = gains 3 e Beryllium = loses 2 e c) State the ionic charge on each of the ions. B = 3+ Cl = 1 N = 3 Be = 2+ d) Name the noble gas that has the same number o electrons as each ion. Noble gas with 2 e = Helium Noble gas with 18 e = Argon Noble gas with 10 e = Neon Noble gas with 2 e = Helium Nov 21 8:13 PM 7. A new element, Ontarium (On), has been formed. We know that it is a halogen. a) How many electrons does it have in its outer orbit? It has 7 electrons in its outer level. b) What will be the name of the compound it forms with sodium? Sodium Ontaride c) What will be the name of the compound it forms with calcium? Calcium Ontaride d) Predict the formulas of the compounds names in (b) and predict (c). NaOn and CaOn 2 Nov 21 11:13 PM 29
8. Atoms and ions are described as isoelectric if they have the same number of electrons. Name the noble gas that is isoelectric with each of the following stable ions. a) Li + He b) F Ne c) Ca 2+ Ar d) S 2 Ar e) Br Kr f) Rb + Kr Nov 21 8:13 PM BONDING Electrons can be donated, received or shared in order to form chemical compounds General rule : compounds form to become stable (like noble gases) Ionic Compounds Made of positive (+) and negative ( ) ions Transfer of electrons from a metal to a nonmetal Come together because of an electrostatic attraction (Ionic Bond) Na + + Cl NaCl 1 + 1 0 Metal atoms lose electrons to form (+) ions Nonmetals atoms gain those electrons to form ( ) ions The result is a compound that is electrically neutral The sum of the charges on the (+) ion equals the sum of the charges on the ( )ion Nov 16 10:18 AM 30
How to Draw Atoms Bonding in Ionic Compounds 1) Write the symbols 2) Draw the electrons around each symbol (Lewis Structure) 3)Draw arrows to show the transfer of electrons 4) Determine the charge of each ion and write the formula and new Lewis structure for each atom 5) Ensure the sum of the charges is 0 and write the chemical formula Nov 23 4:22 PM Chemical Formulas Are the combination of symbols and the ratios of each element in a compound Example: MgCl 2 (this compound has one Mg 2+ ion for every 2Cl 1 ions) Nov 23 4:24 PM 31
Your TASK: Show bonding between 1. Li + Cl 2. Be + F 3. Mg + S 4. Al + Cl 5. Al + O Page 189 Understanding Concepts 1 4 Brain Pop Movies Ions Chemical Bonds Nov 23 4:25 PM 5.8 Ionic Compounds Writing formulas for Ionic Compounds Rule 1 Write the Symbols of the elements, positive ion first Rule 2 Write the ionic charges above each symbol to indicate the stable ion that each element forms Rule 3 Determine the number of ions of each type, so that the total ionic charge is ZERO Rule 4 Write the formula using subscripts to indicate the number of ions of each type (Subscript 1 is unnecessary. Have the lowest number of ions that will produce a electrically neutral charge) Crisscross Rule (replaces rule 2,3,4) E.g What is the formula for the ionic compounds formed by calcium and iodine? Nov 23 4:25 PM 32
Potassium Bromide Magnesium phosphide Lithium oxide Calcium nitide Nov 25 11:25 AM Nov 29 12:58 PM 33
Cross over method exceptions When using the cross over method you must have the lowest whole number ratio that will give a net charge of ZERO Al 3+ N 3 = AlN and not Al 3 N 3 Therefore if you choose the cross over method make sure it is the LOWEST WHOLE # RATIO Nov 23 4:29 PM Calcium Oxide Lead (IV) oxide Nov 25 1:14 PM 34
Naming Ionic Compounds The name of the element with the positive valence is written first (the metal) followed by the stem of the name of the element with the negative valence and the ending ide Your TASK: Page 195 #1 5 Nov 25 4:11 PM Nov 25 11:32 AM 35
Practice Naming 1. LiBr 2. AlCl 3 3. Rb 2 S 4. Mg 3 P 2 1. Lithium bromide 2. aluminum chloride 3. Rubidium sulfide 4. Magnesium phophide Nov 23 4:29 PM Practice Writing formulas 1. Sodium sulfide 2. Aluminum Bromide 3. Barium Iodide 4. Magnesium Nitride 5. Aluminum Nitride Na 2 S AlBr 3 BaI 2 Mg 3 N 2 AlN Nov 23 4:32 PM 36
Multivalent Metals - like other metals - they lose electrons BUT... can lose different numbers of electrons. Therefore they are Metals that can form more than one kind of ion The metals ionic charge is indicated in round brackets () using a roman numeral (III) * The roman numeral equals the charge Nov 23 4:27 PM The charge of the multivalent metal must be found. This is done by looking at the non metal whose charge is always the same Nov 23 4:28 PM 37
Roman Numerals for Multivalent Metals Only CuCl 2 is named copper(ii) chloride. (copper is in the Cu 2+ form.) CuCl is named copper(i) chloride. (the copper is in the Cu + form.) Nov 23 4:30 PM Nov 29 9:56 AM 38
Practice with Multivalent Metals CrBr 3 TiO 2 AuCl 3 Chromium (III) Bromide Titanium (IV) Oxide Gold (III) Chloride Nov 23 4:31 PM Polyatomic Ion a charged group of atoms that chemically acts as a single particle with an overall ionic charge Writing formulas for polyatomic compounds Rule 1 : Write the symbol of the cation and then the polyatomic group Na SO 4 Rule 2 : Write ionic charges Na 1+ SO 4 2 5.9 Polyatomic Compounds Rule 3 : Choose the # of ions to balance the charge 2 Na 1+ 1 SO 4 2 Rule 4 : Write the formula using subscripts Na 2 SO 4 Note: you may need to place brackets around a polyatomic ion symbol if its numerical subscript is greater than one. Nov 23 4:33 PM 39
8 Common ates You must known/memorize the names and chemical formulas of the 8 common ates Nov 23 4:35 PM Other polyatomic ions you should be familiar with include: NH 4 + : ammonium OH 1 : hydroxide Oct 26 2:52 PM 40
Writing formulas for polyatomic compounds 1. Write the a chemical formula for sodium chlorite Sodium is in Group 1 and forms 1+ ions. sodium is Na 1+ 2. The ite suffix in chlorite suggests that it may be a polyatomic ion. Find the name chlorite in the table of polyatomic ions and list its formula and charge. chlorite is ClO 2 3. Since the 1+ charge on the sodium ion is balanced by the 1 charge on chlorite, one of each ion is needed in the formula. 4. The chemical formula of sodium chlorite is NaClO 2. Nov 23 4:37 PM Writing formulas for polyatomic compounds (crisscross method) Nov 23 4:39 PM 41
Writing formulas for polyatomic compounds 1. Write the chemical formula for Iron(III) Sulfate The Roman numeral III indicates that the iron ion has a 3+ charge. iron(iii) is Fe 3+ Sulfate has the ate ending so it is probably a polyatomic ion. A quick look at the table of polyatomic ions confirms this. sulfate is SO 4 2 2. Balance the charges. 2 (Fe 3+ ) = 6+ 3 (SO 2 4 ) = 6 (6+) + (6 ) = net charge=0 The sulfate symbol gets the subscript 3: (SO 4 ) 3. (Note the use of brackets to separate the 4 from the 3. Without them the polyatomic ion formula would show 43 oxygen atoms: SO 43.) 3. Write the formula. The chemical formula for iron(iii) sulfate is Fe 2 (SO 4 ) 3. Nov 23 4:39 PM Naming polyatomic ions examples Give the name for each of the following: Answers: Zn(OH) 2 Pb(NO 3 ) 2 Mg(CH 3 COO) 2 Na 3 BO 3 K 2 Cr 2 O 7 Zinc Hydroxide Lead (II) Nitrate Magnesium Acetate Sodium Borate Potassium Dichromate Nov 23 4:42 PM 42
pg 195 Ques 6 9 Polyatomic Worksheet pg 198 Questions 1,3,4 Nov 30 11:33 AM Chapter 5 Review for test 1 10, 13, 15 Nov 23 4:43 PM 43
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