CHEMISTRY ACTIVITY BOOK INTRODUCTION TO CHEMISTRY. MATTER. Science Physical Science Life Science Earth science Physics Botany Geography Chemistry Zoology Geology Ecology Anatomy Branches of chemistry chemistry Organic chemistry Inorganic chemistry Physical chemistry Analytical chemistry Biochemistry 1 GLOSSARY - CONTENT SPECIFIC VOCABULARY – BRANCHES OF CHEMISTRY Read the definition and provide a suitable terms and translation for them from the box Chemistry biochemistry matter organic chemistry analytical chemistry science TERM (TRANSLATION) inorganic chemistry physical chemistry DEFINITION anything that has mass and occupies space the study of the composition of matter and the changes it undergoes the study of living things the study of chemicals containing carbon the study of chemicals that do not, in general, contain carbon a body knowledge obtained through a set of methods and techniques the study of the mechanism, the rate, and the energy transfer that occurs when matter undergoes a change the study of the composition of substances 2 Activity 1.2 Match the project with the proper chemistry discipline. a. measuring mercury in seawater 1. biochemistry b. studying enzymes in cells 2. organic chemistry c. measuring the electrical properties of solutions 3. inorganic chemistry d. synthesizing new carbon compounds 4. physical chemistry e. making new compounds for energy processes 5. analytical chemistry Activity 1.3 In this activity you have to state your opinion. Stating your Opinion In my opinion, … My personal view is that … I might be wrong but … Personally, I think … That is why I think … I am sure/certain/convinced that … I have read that … List three careers that require some knowledge of chemistry. State why you think they need knowledge of chemistry. …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… ………………. 3 1. MATTER GLOSSARY - CONTENT SPECIFIC VOCABULARY - MATTER Read the definition and provide a suitable terms and translation for them from the box luster hardness mass volume light transmission flexibility elasticity conductivity TERM (TRANSLATION) color texture brittleness density solubility DEFINITION The ability to dissolve in water or any solvent. The ability to allow light to pass through. How an object feels How much space a substance takes up The color a substance looks like How much stuff there is in a substance (how heavy an object is) How tightly packed the molecules in a substance are The ability to bend without breaking. The ability to reflect light. Shiny. Resistance to being scratched by another material Easily breaks into pieces. Fragile. The ability to let heat and electricity pass through it. The ability to be stretched without breaking, to go back to original size and shape. 4 Activity 2.1 Properties of matter Identify the property of matter as described. Choose from the list: COLOR ELASTICITY LUSTER FLEXIBILITY TEXTURE BRITTLENESS MASS HARDNESS VOLUME CONDUCTIVITY DENSITY LIGHT TRANSMISSION SOLUBILITY 1. Chlorine gas is yellow- green. ……………………………… 2. Iron will always sink in water. …………………………………. 3. A paper clip can be bent. ……………………………………….. 4. A rock is 29 kilograms………………….. 5. No mineral can scratch a diamond except another diamond. …………. 6. When polished, metals are very shiny like mirrors. …………………. 7. One kilogram of cotton takes up more space than one kilogram of sugar. ………………………….. 8. Salt easily dissolves in water. …………………………. 9. Copper is a good material to make electrical wires and cooking pots. ……………………………………. 10.The glass bottle is transparent. ……………………………. 11.Plastic is very smooth to touch ………………………………… 12.An egg breaks into pieces when thrown on the ground. ……………… 13.A rubber band can be stretched and it returns to its original shape. ………………………………….. 5 PHYSICAL AND CHEMICAL PROPERTIES OF MATTER Activity 2.2 What are the differences between physical properties and chemical properties of matter? Give examples of each. Physical Properties Examples: Chemical Properties Examples: 6 Activity 2.3 Define each physical property of matter and fill in the blanks for each example given. Name of the Property Definition Examples 1. State of Matter There are three states of matter. Water in a lake is found in the …………..state, water in your ice cube tray is found in the …………….. state, and water in steam is found in the ………… state. 2. Taste Sugar tastes …………… but lemons taste ………... Nothing in a chemistry lab should ever be ……………. Even if one of the ingredients is a common food item, once it is used for a lab, it is considered potentially ……………. 3. Odor Old dirty gym socks smell …………………. and roses smell …………. Never ………….anything in a chemistry lab unless instructed to do so. If smelling a substance, the ………………. method should be used to sniff it. A fire truck is ………….. but the sky on a sunny day is ……………. The leaves on the trees in the summer are …………, but the color of the sun is ……………. . The color of an orange is ………….! 4. Color 7 A piece of paper is ………… because it does not reflect much light, but the chrome on a car is …………… because it reflects a lot of light. Another dull thing is ……………. and another shiny thing is …………... A piece of glass is ………… , meaning that it lets all light pass through it, maple syrup is …………..because it lets some light through it, and mud is …………….. because it lets no light pass through it. The surface of a bowl feels ………… but the surface of the cement sidewalk feels ………….. The fur of a cat feels ………….. The surface of an eraser feels …………. . 5. Luster 6. Clarity 7. Texture 8. Hardness On Mohs’s hardness scale of minerals, a ………… is the hardest thing known on Earth with a hardness level of …………. An emerald is also hard but it has a hardness level of ……………... 9. Solubility Water and vinegar mix together completely and therefore, vinegar is ………….. in water. Salt is also ……….. in water because it will dissolve completely in water. Neither oil nor sand will dissolve in water, and that is why they are considered ……….. in water. 8 Name of the Property Definition Examples Water is ………..viscous than oil, and that is why it pours out of its container more easily than oil does. Ketchup is ………. viscous than oil, and that is why it’s ……….. for it to pour out of its container. 10. Viscosity 11.Malleability …………….. is very malleable and that is why we use it to make foil to wrap our food. Other substances like glass are ……... malleable, because it would break instead of change shape. Wood is …......................... while copper is …………... 12.Ductility Many metals like …………… and ………. can easily be drawn into a thin wire. Substances like water and cement are not …………….. . 13.Density Rubber is ………… dense than water and that is why it will float in water. A penny is……….. dense than water and that is why it will sink to the bottom of the water. Water in its 9 ………….. state is less dense than water in its ……… state. That is why ice floats on water. ……………….. is a ………. electrical conductor, and that is why it is used as the main material for the wiring found in most homes and electronics. Plastic is ………. a good conductor of electricity and that is why it is used to ………… electrical wires. 14.Electrical Conductivity 15.Melting Point The melting point of water is ……. °C and the boiling point of water is …… °C. The melting point of ……….. is 1063°C and the ……….. point of gold is 2856°C 16.Boiling Point 17.Crystal Form If you look with a high powered microscope, you can observe that sugar crystals are oblong and slanted at the sides, but the crystal form of salt is shaped more like a …………... 10 Name of the Property Definition 18.Magnetism Examples Substances like steel are ……………. to magnets so they are considered ………………. Substances like glass are ……………. attracted to magnets and are called ……………….. . CHEMICAL PROPERTIES OF MATTER Activity 2.4 Define each chemical property of matter and fill in the blanks for each example given. Name of the Property Definition Examples 19.Combustibility Glass is not ……………. Dry wood is ……….. combustible than wet wood. ……….. fuels, like coal, natural gas, and gasoline, are combustible. 20.Reactivity with Water Some substances, like …………… are very reactive with water, and so they have to be stored in a water-free environment. Even the water vapor in the air can cause a reaction so these substances must be stored under ……………….. 11 STATES OF MATTER GLOSSARY - CONTENT SPECIFIC VOCABULARY – STATES OF MATTER Read the definition and provide a suitable terms and translation for them from the box condense volume evaporate gas liquid boiling point mass melt solid matter freeze melting point TERM (TRANSLATION) DEFINITION anything that has mass and occupies space a measure of how much matter is in an object (the amount of matter in an object) matter in a state that has a definite shape and volume matter in a state that has a definite volume but no definite shape matter in a state that has no definite shape or volume to change slowly from liquid to gas to change from liquid to solid to change from gas to liquid to change from a solid to a liquid the space an object takes up temperature at which a liquid becomes steam (vapor) or gas temperature at which a solid becomes a liquid 12 Activity 2.5 Diagrams of the arrangement of particles Draw a simple diagram of the arrangement of particles Solid Liquid Gas Activity 2.6 Classify the following characteristics into solids, liquids or gases Definite shape Changeable Hardness Molecules close and tidy volume Changeable Definite volume Viscosity Molecules close and shape untidy Changeable Definite volume Expansion Molecules distant shape Solid Liquid 13 Gas Activity 2.7 Cloze test Fill in the blanks. Some answers may be used more than once. condense heat mass solid gas liquid matter Everything that you are able to see, touch, smell, and feel is matter. Matter is anything that has ……………. and takes up space. The amount of matter in an object is called it’s …………… ………… can be classified according to its state. A …………. piece of matter has definite volume and shape. A …………….. has no definite shape, but has a definite volume. A …………….., such as oxygen, has neither a definite volume nor shape. When ………….. energy is added to matter, changes to its state may occur. For instance, when a solid piece of ice is heated, it may melt, becoming a liquid. When heat is added to a liquid, it can evaporate, becoming a …………….. When heat is taken away, a liquid can freeze, becoming a ……………….. When heat is taken away from a gas, it can ……………, becoming a liquid. The following statements define certain terms used in connection with changes of state. The word define is a command word often used at the start of certain exam questions. It means you must answer with a short, but complete, meaning of the term. Definitions use the words which or that to link the parts of the definition together. For example, Melting is the process that takes place when a solid turns into a liquid. Activity 2.8 How to write a definition Complete these first examples by pairing up the two parts of the sentence. Put the letter that goes with each number in the box provided beneath the table. The first example has been done for you. Once you have completed exercise, write out the whole sentence for each definition to help you remember it. 14 1 Freezing is the process ………. A …… that can flow from one place to another 2 Fluids are substances …….. B ……… which a solid turns into a liquid 3 The melting point is the temperature at …….. C …….. that turns a liquid into a gas 4 Boiling is a process …….. D ……. that turns a liquid into a solid 5 Solidification process….. the E ……that transforms a liquid into a gas 6 Evaporation is the process …… F ………that transforms a solid into a gas 7 Sublimation process…… the G …….that transforms a liquid into a solid 8 Condensation is the process ……… H ……that transforms a gas into a liquid 1 2 is is 3 4 5 6 7 8 D …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… 15 Activity 2.9 Fill the blanks for the names of phase transitions and phases in the following diagram. 16 PHYSICAL AND CHEMICAL CHANGES Activity 2.10 Complete the following diagram by inserting words and phrases from each list below. Types: physical changes, chemical changes Characteristics: new substances formed, no new substances form, little change in temperature, large change in temperature, often a change in color, usually no change in color, change is hard to reverse, change is easy to reverse Examples: condensation, combustion, hard boil an egg, rusting, evaporation, melting gold 17 Activity 2.11 Fill in the blank spaces with either ‘Physical’ or ‘Chemical’ 1. Boiling water is a ………………. change. 2. Bending a metal pole is a …………………change. 3. Boiling potatoes is a………………… change. 4. Cutting an orange is a ……………..change. 5. Cutting a sheet of paper is a …………………… change. 6. Baking cake is a ……………………. change. 7. Melting snow is a ……………………change. 8. Slicing a banana is a ……………change. 9. Molding shapes with play dough is a ………………… change. 10. Melting glass into different shapes is a …………………change. 11. Mixing a cocktail of fruit juice is a ……………… change. 12. Rusting of a metal gate is a ……………….. change. 13. Washing clothes with bleach leads to a ………………. change. 14. A ……………... change leads to the formation of a new chemical substance. 15. A ………… change does not lead to the change of the chemical composition of a substance. 16. Adding baking powder to scrambled eggs is a …………….. change 18 Activity 2.12 Determine if the following processes are physical or chemical changes a. boil - …………………………………………………………………………… b. combustion - …………………………………………………………………. c. condense -……………………………………………………………………… d. corrode - ………………………………………………………………………. e. crumple - …………………………………………………………………….. f. ferment - ………………………………………………………………………. g. melt - ………………………………………………………………………… h. rust - …………………………………………………………………………… i. crush - ………………………………………………………………………… j. freeze - …………………………………………………………………………. k. oxidize - ……………………………………………………………………….. l. tarnish - ………………………………………………………………………… m. explode - ……………………………………………………………………. n. grind - ……………………………………………………………………….. o. rot - …………………………………………………………………………. p. vaporize - ……………………………………………………………………… q. photosynthesis - ………………………………………………………………. r. sublimation – …………………………………………………………………... 19 Classification of matter Scientists classify matter by looking at the types of particles that it contains. The particles can be single atoms. Or the particles can be groups of atoms joined together, called molecules. This diagram contains two different kinds of particles. They are different kinds and shown shaded as different colors. Each particle is called a single atom. This diagram contains only one kind of particle. Each particle is made up of two atoms joined together. Each particle in this diagram is a molecule. What can you say about the particles shown in the following diagrams? 20 Activity 2.13 Pure substances and mixtures Write four examples of pure substances and four mixtures. Also write the substances they are made up of. Pure substances Mixtures The mixture is made up of Activity 2.14 Pure substance and mixture Look at the images and write down whether the following materials are a pure substance or a mixture. In the case of a pure substance, state whether it is an element or a compound. 21 Use the following sentences choosing the appropriate expressions to give reasons for your answer: The a mixture first material an element The is second The third a compound because it is formed by one type of atom several types of atoms chemically bonded not chemically bonded ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………….. 22 Activity 2.15 Classification of matter Answer the questions below and then complete the diagram, which shows the classification of matter by using the terms and connecting phrases in the table. You can use a phrase or term only once. Then list examples of each type of matter. Terms Atom Compound Element Homogeneous mixture Heterogeneous mixture Matter Mixture Molecule Pure substance Connecting phrases Substances with identifying set of characteristics Substances combined without reacting Substances formed by combining other substances Substances that cannot be broken down any further Mixtures which are uniform Mixtures that are not uniform The smallest particle of an element The smallest particle of many compounds Examples Air Aluminum Calcium carbonate Candy bar Carbon dioxide Chocolate Copper Copper (II) sulfate Cotton Dirt (from a garden) Drinking water Hydrogen Oxygen Paint Salad Silver Sugar Table salt Sulfur Glass Distilled water What are the similarities and differences between a compound and a homogeneous mixture? (this is answered for you as an example): A compound and a homogeneous mixture are similar because they are made of more than one substance and look uniform A compound and a homogeneous mixture are different because a compound has chemically combined elements (always the same proportions) and a homogeneous mixture is physically combined substances (elements or compounds) evenly mixed. 23 What are the similarities and differences between an atom and an element? ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. .......................................................................................................................... What are the similarities and differences between a molecule and an atom? …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… What are the similarities and differences between a pure substance and an element? …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… ……………………………………………………………………………………. 24 E E E 25 E Classification of Elements Activity 2.16 Arrangement of elements in a Periodic Table Use green, blue and red colors to show phases of elements. In the periodic table above show solids with green background, liquids with blue background, and gases with red background. 1 1 2 2 3 3 4 4 5 5 6 6 7 7 26 The Names of the Elements Activity 2.17 Where did names of elements come from? As you look at your periodic table, you will recognize some of the more common elements, but you will probably also notice that some elements have strange names. Where did all of these names come from? You will find out as you work through the exercises below. Some elements are named after places. Write the name in English and Russian, and the symbol of the element that is named after the place given in each question. 1. 2. 3. 4. 5. 6. 7. 8. Russia …………………………………………………………………….. The country of France ……………………………………………………. The country of Germany………………………………………………….. America:…………………………………………………………………… The country of Poland. …………………………………………………… Scandinavia: ……………………………………………………………… The city of Berkeley:…………………………………………………….. The continent of Europe………………………………………………… Four of the elements are named after planets. Complete the chart below for the elements named after planets. Element Name (Symbol) Planet Name ………………………………. …………………………. ……………………………….. ………………………… ………………………………. …………………………. ……………………………… …………………………… Many elements are named after famous scientists. The scientist’s last name is used along with the ending “ium”. Write the element after each scientist given. 1. 2. 3. 4. 5. 6. Albert Einstein: ……………………………………………………………. Pierre and Marie Curie: ………………………………………………….. Enrico Fermi: …………………………………………………………….. Alfred Nobel: ………………………………………………………………. Dmitri Mendeleyev: ………………………………………………………. Ernest Lawrence: …………………………………………………………. 27 You’ve probably noticed that some of the names of the elements do not match the symbols. That’s because some symbols are made from Latin name of the element. Look up the symbol on the Periodic Table and see if you can match the English name to the Latin name. Use each letter once. English 1 Antimony 2 Copper 3 Gold 4 Iron 5 Lead 6 Mercury 7 Potassium 8 Silver 9 Sodium 10 Tin 11 Tungsten A B C D E F G H I J K Latin Correct answer Argentum Antimony – Stibium Aurum Cuprum Ferrum Hydrargyrum Kalium Natrium Plumbum Stannum Stibium Wolfram Some elements named for mythological characters 1. ……………… named after Thor, the Scandinavian god of war. ………………. is used as a fuel for nuclear weapons. 2. ………………… —named after Titans, supermen of Greek mythology. ………………….. is a super-element because it is very resistant to acid. 3. ………………….. —named after the Scandinavian goddess of beauty, Vandis, because …………..; compounds form such beautiful colors. 4. ………………. and ……………….. named after the mythological Greek king, Tantalus, and his daughter, Princess Niobe. Like the king and his daughter, ………………. and ……………. are often found together. Some elements named for their properties 1. …………………… —from Greek chloros meaning “green.” ……………. is a greenish yellow gas. 2. ……………… from Greek iodos meaning “violet.” 3. ………………. —from Greek argos meaning “lazy.” …………… is an extremely unreactive gas, so it was thought too lazy to react. 4. ………………… from Greek kobold meaning “goblin” or “evil spirit.” ………… miners often died suddenly and unexpectedly, which was probably due to ingesting arsenic found with the …………… ore in the German mines. 28 Activity 2.18 Symbols of chemical elements Write the symbol of the elements mentioned in each sentence. 1. Mercury is used in some thermometers ………………… 2. Uranium provides us the fuel for nuclear power ………………… 3. Bones and teeth are made mostly of calcium………………….. 4. Diamonds are made of carbon …………………. 5. Some balloons are filled with helium……………… 6. We get the oxygen that we breathe from the air ………… 7. Germs get killed by chlorine in swimming pools ……………. 8. Our air is 78 percent nitrogen …………… 9. Magnesium is found in some heartburn medicine ………… 10. Amethyst jewelry is made of silicon ………………. 11. Bananas are a source of potassium for the body…………. 12. Sulfur is the main ingredient in gunpowder ………………. 13. Pennies are coated with copper …………………. 14. Tin is used to make foil and cans …………. 15. A healthy thyroid gland needs iodine …………… 16. Lead is a heavy metal that is toxic to humans …………… 17. Gold is one of a few elements that is found in its pure form ……….. 18. Silver can be used to make mirrors ………….. 19. Zinc is used to coat many objects made of steel ………………. 20. Sodium can be found in salt ……….. 21. Magnets are made mostly of iron …………. 22. Phosphorus is used to make objects glow……… 29 Activity 2.18 Elements in some common compounds Below is a list of the chemical formulas of some common compounds. Write the name of the elements they are made of 1. Water H2O ……………………………………………………………… 2. Table salt NaCl …………………………………………………………… 3. Sulfuric acid H2SO4 ……………………………………………………… 4. Sand SiO2 ………………………………………………………………… 5. Rust Fe2O3 ……………………………………………………………….. 6. Baking soda NaHCO3………………………………………………….. 7. Photo developer AgCl …………………………………………………….. 8. Ammonia NH3 ……………………………………………………………. 9. Fool’s Gold FeS2 ………………………………………………………. 10. Stomach Acid HCl ……………………………………………………… Activity 2.19 Symbols and names of elements Symbols of the elements are used in the sentences below. Write the name of the elements of the symbol used in the sentence in the space provided. 1. I ……………………. is used by campers to purify water 2. Mg ………………………. is used to treat skin rashes. 3. Some switches contain Hg ……………………… 4. Some glass plates are coated with Au ………………… 5. Some pots and pans are made of Al …………………. 6. Wire made of Ni ……………….. is used in toasters. 7. Some bowls and plates are made of Sn ……………. 8. Pb ………………. is used to make television screens. 9. P ………………… is used by the body. 10. Some liquid soaps use K ……………… 30 11. Cu ……………… is used for paint on ships. 12. Zn ……….. is used to make brass. 13. Ca …………….. is used in building materials. 14. He …………….. is used in bar code scanners. 15. Some weapons are made from U………………………… Activity Uses of Some of the Elements: Choose your answers for questions 1-19 from the following list of elements. Each element is used only once. If an element appears twice in the list, use it twice! aluminum uranium lead neon carbon arsenic calcium copper hydrogen chlorine copper chromium fluorine iron iodine iron mercury tungsten magnesium 1. What metallic element is sometimes used in flares and flashbulbs because it burns with a bright, white light? ………………………………… 2. What element is used to disinfect swimming pools?................................. 3. What element is needed for strong bones and teeth? ……………………. 4. What element is found in liver and is needed to prevent anemia or “tired” blood?.......................................................... 5. What element is added to toothpaste and city water systems to help tooth decay? ……………………………………………….. 6. Which element is used to “paint” the skin to prevent infection from cuts and scratches…………………………………………………. 7. What element is used in bright, flashing advertising signs? ……………… 8. What element is a liquid metal used in thermometers? …………………… 9. Which element is used for the shiny trim on cars? ……………………… 10. Which element is used in light bulbs as a filament? …………………… 31 11. Which element is used as rat poison and is found in the title of the murder mystery “__________ and Old Lace”? …………………………………. 12. What element is found in the coins? …………………………………. 13. A diamond and your pencil lead (graphite) are made of this same element…………………. 14. Steel is formed when a little bit of carbon is added to this element. (The carbon gives strength and hardness to the steel.) ……………………….. 15. What element is used as a shield to protect people from radioactive substances? …………………………………………………… 16. What element has the lowest density of all of the elements? ………………….. 17. What element was used to make the first atomic bomb? ………………… 18. Which element is rolled into a foil found and used in your kitchen? ……………………… 19. What element used to be mined in the Upper Peninsula of Michigan? Several towns in the Upper Peninsula are named after this element, including “………………. Harbor.” 32 ALLOTROPES Activity 2.20 Allotropes of carbon atom Look at these two diagrams: The first structure is carbon graphite and the second one is carbon diamond. Are both structures formed by same balls? ………………………………………….. Are they identical? ……………………………………………………………… ………………………………………………………………………………….. What differences can you find? Complete this table with the following words: layers longer length tetrahedral shape four equal three carbon atoms Features General structure C (diamond) Carbon atoms form covalent bonds in a …………………….. C (graphite) four Carbon atoms form four covalent bonds in …………………….. Number of chemical bonds Each carbon atom is bonded to Each carbon atom is bonded to ………….. carbon atoms …………. In an hexagonal pattern, in the same plain. length of All the bonds have the same The fourth bond is …………… chemical ……………….. than the others and is established bonds between the layers 33 “Classify in similarities and differences” Using the phrases in the boxes complete the table similarities and differences between C(diamond) and C(graphite) Both of them are formed by carbon atoms Each one has a different structure The carbon atoms form covalent bonds As a consequence of the different giant covalent structure, they have different appearance, and different properties They are elements They have different color Both of them are solids They have different melting point... They are represented by the same symbol but with a bottom specification Similarities and differences between C(diamond) and C(graphite) Similarities Differences 34 Physical appearance Use the Internet to search for two photographs. One of them a diamond and the other of graphite, and try to find the physical properties of both. Carbon diamond Symbol: Physical state: Colour: Melting point: Uses: Carbon graphite Symbol: Physical state: Color: Melting point: Uses 35 In some elements the atoms pair up: Oxygen is an element like this. It is formed by two atoms. This particle is called a molecule. It can be represented by a formula: O2 Symbol of element O2 Number of atoms that form the molecule Molecules of Oxygen, Hydrogen, Nitrogen, Fluorine, Chlorine, Bromine and Iodine are diatomic: O2, H2, N2, F2, Cl2, Br2, I2 This is the model of an Oxygen molecule. It’s diatomic because is formed by two equal atoms. Look at this table. All of them are elements, but they have different structures: Element Aluminum Symbol Al Mercury Hg Helium He Oxygen O2 36 Diagram Nitrogen N2 Carbon (graphite) C (graphite) Carbon (diamond) C (diamond) Tick the correct properties of all these elements Properties Helium Oxygen Nitrogen Aluminum Mercury Formed by molecules with 2 atoms formed by only one atom, without any chemical bond A gas at ordinary temperature A solid at ordinary temperature A liquid at ordinary temperature formed by a metallic structure Formed by a giant covalent structure 37 Carbon (graphite) Carbon (diamond) What elements are solids at ordinary temperature? …………………………………………………………………………………… …………………………………………………………………………………… What elements are liquids? …………………………………………………………………………………… What elements are gases? …………………………………………………………………………………… ……………………………………………………………………………………. What are the differences and the similarities between the models of the Carbon diamond and graphite and the models of the other elements? …………………………………………………………………………………… …………………………………………………………………………………… ………………………………………………………………………………….. …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… ……………………………………………………………………………………. What are the similarities between Oxygen and Nitrogen? …………………………………………………………………………………… ………………………………………………………………………………….. What are the similarities and the differences between Oxygen and Helium? …………………………………………………………………………………… …………………………………………………………………………………… ……………………………………………………………………………………. What are the similarities and the differences between Oxygen and Aluminum? …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… What are the similarities and the differences between Aluminum and Mercury? …………………………………………………………………………………… ……………………………………………………………………………………. 38 COMPOUNDS A compound is a substance that can be broken down into simple substances or elements by a chemical reaction. Compounds can be represented by a molecular formula. A water molecule is formed by two Hydrogen atoms and one Oxygen atom. So, its formula is H2O and it is a compound. CO2, CH4; NaCl….. are compounds too. Compounds have different properties to their constituent elements Also a compound is a substance that is made up of two or more different elements combined together chemically. An element is a substance that cannot be split up into simpler substances by chemical means. Activity 2.21 “fill the gaps” with “elements” or “compounds”: 1. …………………… are substances that can be split up into simpler substances by chemical means 2. ……………………. are substances that are formed by more than a kind of atom. 3. ………………………..are substances that cannot be split up into simpler substances by chemical means 4. ………………………are substances that are formed by a kind of atom. Activity 2.22 “classify “these substances as elements and compounds H2, O2; Hg, N2, Ar, C(graphite), CO2, CH4; NaCl (sodium chloride), H2O, NH3 (ammonia), Cu, Cl2, C2H6 (ethane), Fe2O3 (Iron (III) oxide) ; H2SO4 (sulfuric acid); MgCl2 (magnesium chloride) Elements Compounds 39 Comparing properties of elements and compounds You probably already know some of the properties of sodium chloride, it is the salt used in cooking, at the table, and the main salt in seawater. Properties of the compound sodium chloride, NaCl are compared with the properties of the metal sodium and the non-metal chlorine below: Substance Sodium chloride Sodium Chlorine Properties solid at room temperature, reacts with some elements, colorless, melting point = 801°C solid metal at room temperature, reacts readily with most nonmetal elements and with water, shiny silvery surface, melting point = 98°C gas at room temperature, reacts readily with most metals and nonmetals, yellow, melting point = –101°C Activity: Sodium chloride, sodium and chlorine Compare the properties of the compound, sodium chloride, with the properties of the elements that it consists of. 1. What is the state of sodium chloride, sodium and chlorine at room temperature? ............................. and …………. are both solids while ………… is a gas at room temperature. 2. What colors are sodium chloride, sodium and chlorine? Sodium chloride is …………..; sodium is ……….. and ………, ……… chlorine is a …………. gas. 3. Compare the melting point of sodium chloride with the melting points of sodium and chlorine. Sodium chloride has a ……… melting point (MP) of 801°C, while sodium has a ………. MP of 98°C and chlorine a ……….. ……… MP of –101°C 4. Compare the readiness of sodium chloride, sodium and chlorine to react. Sodium chloride reacts with ………… ………; sodium reacts with ……….. ……………. and ……………. . Chlorine also reacts with …………… ……………. 5. Are the properties of sodium chloride the same as those of sodium and chlorine? ………… . Sodium chloride has …….. ……… properties from those of both sodium and chlorine. 40 Activity: Calcium carbonate, calcium, carbon and oxygen The table following shows the properties of a compound called calcium carbonate CaCO3. Sea shells and limestone rock consist of calcium carbonate. The table also shows the properties of the elements in calcium carbonate: calcium, carbon and oxygen. Substance Properties Calcium carbonate white solid, doesn’t react with water but reacts with acid, melting point = 1339°C Calcium grey solid, reacts with water and acid, melting point = 842°C Carbon black solid, doesn’t react with water or acid, melting point = 3974°C Oxygen colorless gas, doesn’t react with water or acid, melting point = –219°C Complete the sentences comparing the properties of calcium carbonate, calcium, carbon and oxygen. Calcium carbonate is ………. . Calcium is ………. Carbon is …….. and oxygen has ……... That is, the substances are all different ………………… Calcium carbonate, calcium and carbon are all ……. whereas oxygen is a …………… at room temperature. Both …………. and …………. don’t react with water or acid. Calcium carbonate reacts with acid whilst calcium reacts with …….. and ………... There is a wide range of …………… points from –219°C to 3974°C. The properties of the compound, calcium carbonate, are …… ……….. from the ……………… of the elements it is composed of. 41 CHEMICAL FORMULA The symbol of an element represents one atom of that element. A subscript is a number written at the lower right corner behind the symbol of an element. If there is more than one atom of the element, then a subscript is used to indicate the number of atoms. e.g., Cl2 = Chlorine molecule which contains 2 chlorine atoms Parentheses - in some chemical formulas it is necessary to use parentheses. The subscript outside the parentheses refers to all the elements inside the parentheses. Al(NO3)3 In this example there are: one Al (aluminum), three N (nitrogen), and nine O (oxygen) atoms. A coefficient is a number written in front of a chemical symbol and indicates the number of atoms of that element or number of molecules e.g., 3C = 3 carbon atoms 2H2O = 2 water molecules Note: a coefficient multiples the number of atoms of each element in the formula 2H2O = 4 hydrogen and 2 oxygen atoms 42 Sodium chloride is a compound. For each sodium atom (Na) there is one chlorine atom (Cl). It can be shown as Look at the drawings of these molecules. Draw lines to match them to the correct formulae. CO2 HCl H2O CH4 H2O2 43 Activity 2.23 Composition of compounds Count the atoms present in the different compounds by using the coefficients and subscripts. K2CO3 2 potassium atoms 1 carbon atom 3 oxygen atoms Ba3(PO4)2 Na2CrO4 3 CaCl2 4 Al2(CO3)3 Pb(NO3)2 2 (NH4)2Cr2O7 44 Total 6 atoms The relative atomic and molecular masses GLOSSARY - CONTENT SPECIFIC VOCABULARY Read the definition and provide a suitable terms and translation for them from the box The relative atomic mass (Ar) of an element The relative molecular mass (Mr) TERM (TRANSLATION) Mole The molar mass (M) DEFINITION is the average mass of an atom according to relative abundances of its isotopes, on a scale where the mass of one atom of is 12 exactly. It has no units is the relative mass expressed in g and has units of g/mole is the sum of the relative atomic masses of the atoms in the molecular formula. is the amount of a substance 45 Activity 2.24 The molar mass of the following compounds a. KNO3 M(KNO3) = A(K) +A(N) + 3A(O) = 39 + 14 + 3*16 = 101 g/mole b. UF6 ………………………………………………………………………….. c. (NH4)2CO3 …………………………………………………………………………… …………………………………………………………………………… d. Ag2CrO4 …………………………………………………………………………… …………………………………………………………………………… e. H3PO4 …………………………………………………………………………… …………………………………………………………………………… f. Ca(NO3)2 …………………………………………………………………………… ……………………………………………………………………………. g. CH3COOH …………………………………………………………………………… …………………………………………………………………………… h. PbSO4 …………………………………………………………………………… …………………………………………………………………………… i. Pb(NO3)2 …………………………………………………………………………… …………………………………………………………………………… j. Mg(OH)2 …………………………………………………………………………… ………………………………………………………………………….. k. Al2(SO4)3 …………………………………………………………………………… …………………………………………………………………………… …………………………………………………………………………….. 46 Activity 2.25 Unknown element “X” For each of the following compounds “X” is an unknown element. The molecular mass of the compound is given in the bracket. Work out which element X represents. a) XO (40) M(XO) = A(X) + A(O) = A(X) + 16 = 40 A(X) = 40-16 = 24, so X is Mg - magnesium b) X2O (62) …………………………………………………………………………… …………………………………………………………………………… ………………………………………………………………………….. c) XCl2 (110) …………………………………………………………………………… …………………………………………………………………………… …………………………………………………………………………… d) MgX2 (94) …………………………………………………………………………… …………………………………………………………………………… …………………………………………………………………………… e) CX2 (44) …………………………………………………………………………… …………………………………………………………………………… …………………………………………………………………………… f) XNO3 (63) …………………………………………………………………………… …………………………………………………………………………… …………………………………………………………………………… g) X(OH)2 (171) …………………………………………………………………………… …………………………………………………………………………… …………………………………………………………………………… h) X2O3 (188) …………………………………………………………………………… …………………………………………………………………………… …………………………………………………………………………… 47 Percent composition is the percent by mass of each element found in a compound. Example: What is the mass percentage of oxygen in iron (III) hydroxide, Fe(OH)3? Step 1: Find the molecular mass of the compound. 1 Fe = 55.85 g 3O = 3 × 16.00 g = 48.00 g 3H = 3 × 1.008 g = 3.024 g Molecular Mass Fe(OH)3 = 106.87 g/mol Step 2: Find the percentage by dividing the part by the whole and multiplying by 100. W% (O) = 48.00 g O ×100 % = 44.91% 106.87 g Fe(OH) 3 Activity 2.26 Percent composition by mass Solve the following. 1. What is the mass percentage of magnesium in magnesium bromide, MgBr2? …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… ………………………………………………………………………………….. 2. What is the mass percentage of carbon in glucose, C6H12O6? …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………. 48 3. What is the mass percentage of zinc in of Zn3(PO4)2? …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… ………………………………………………………………………………….. …………………………………………………………………………………… 4. What is the mass percentage of Cu in CuCO3? …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… 5. What is the mass percentage of copper in CuCl2? …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… 6. What is the mass percentage of silver in AgNO3? …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… 7. Which has more aluminum by mass, Al2O3 or Al(NO3)3? …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… 49 8. Why is knowledge of percent composition important in the mining process? …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… ………………………………………………………………………………….. 9. A class of compounds called sodium metaphosphates were used as additives to detergents to improve cleaning ability. One of them has a molecular mass of 612g. Analysis shows the composition to be 22.5% Na, 30.4% P, and 47.1% O. Determine the molecular formula of this compound. …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… ………………………………………………………………………………….. 10. Glucose, one of the main sources of energy used by living organisms, has a molecular mass of 180.2g. Chemical analysis shows that glucose is 40.0% C, 6.71% H and 53.3% O. Determine glucose’s molecular formula. …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………… ………………………………………………………………………………….. 50 The law of definite proportions states that regardless of the amount, a compound is always composed of the same elements in the same proportion by mass. 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑎𝑛 𝑒𝑙𝑒𝑚𝑒𝑛𝑡 𝑊% 𝑜𝑓 𝑎𝑛 𝑒𝑙𝑒𝑚𝑒𝑛𝑡 = ∗ 100% 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑎 𝑐𝑜𝑚𝑝𝑜𝑢𝑛𝑑 Example: Let us consider any compound, say carbon dioxide. We know that it is made up of carbon and oxygen. Atomic mass of carbon is 12, while that of Oxygen is 16. So, basically, there are 12 grams of Carbon and 16 x 2 = 32 grams of Oxygen in carbon dioxide. The ratio of Carbon to oxygen would be: 12: 32 = 6: 16 = 3: 8. The simple ratio is 3: 8. So, taking any grams of CO2, it will always contain 3 parts of Carbon and 8 parts of Oxygen. This will remain a fixed ratio. If we take 50 grams of carbon dioxide, it will have 50 X 3/11 = 13.64 grams of Carbon and 50 x 8/11 = 36.36 grams of oxygen. Activity 2.27 The law of definite proportions Solve the following problems 1. A 20.0-g sample of sucrose contains 8.4 g of carbon. What is the mass percentage of carbon in sucrose? Show your work. ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… 51 2. Sucrose is 51.50% oxygen. How many grams of oxygen are in 20.0 g of sucrose? Show your work ……………………………………………………………………………… ……………………………………………………………………………… ……………………………………………………………………………… ……………………………………………………………………………… ………………………………………………………………………………. 3. 78.0 g sample of an unknown compound contains 12.4 g of hydrogen. What is the percent by mass of hydrogen in the compound? ……………………………………………………………………………… ……………………………………………………………………………… ……………………………………………………………………………… ……………………………………………………………………………… ………………………………………………………………………………. 4. How many grams of hydrogen are in 100.0 g of fructose, C6H12O6? …………………………………………………………………………… …………………………………………………………………………… …………………………………………………………………………… …………………………………………………………………………… …………………………………………………………………………… 5. A 20.00 g sample of ordinary table salt contains 12.13g of chlorine. Calculate the mass percentage of each element in salt. …………………………………………………………………………… …………………………………………………………………………… …………………………………………………………………………… …………………………………………………………………………… …………………………………………………………………………… ……………………………………………………………………………... 6. A sample of baking soda contains 34.48 grams of sodium, 1.51 grams of hydrogen, 18.02 grams of carbon and 72.00 grams of oxygen. a) What is the total mass of the sample? ………………………………………………………………………… …………………………………………………………………………. b) What is the mass percentage of each element in baking soda? ………………………………………………………………………… ………………………………………………………………………… ………………………………………………………………………… ………………………………………………………………………… ………………………………………………………………………… 52 53 54 55
