Lesson 2: Elements and Compounds PDF

LESSON(2) ELEMENTS AND COMPOUNDS  OBJECTIVES: 1. Identify the types of matter. 2. Differentiate between element and compound. 3. Recognize the elements and its abundance in nature 4. Recognize the periodic table. 5. Recognize the compound and their properties 6. Explain the separatio...

LESSON(2) ELEMENTS AND COMPOUNDS  OBJECTIVES: 1. Identify the types of matter. 2. Differentiate between element and compound. 3. Recognize the elements and its abundance in nature 4. Recognize the periodic table. 5. Recognize the compound and their properties 6. Explain the separation of compounds. 7. Conclude the law of definite proportion. 8. Conclude the law of multiple proportion. 2  OBJECTIVES: 1. Identify the types of matter. 2. Differentiate between element and compound. 3. Recognize the elements and its abundance in nature 4. Recognize the periodic table. 3 Matter: Any thing around us that has mass and takes amount of space. What does any matter consist of ? Matte Freely Atoms r Molecules Q1) Classify the following matters into element , compound and mixture; Sodium : element Water : Compound fruit salad: Mixture Q2)Are all matters around us similar, or they have different shapes?  Matter consists of Similar molecules different molecules Matter Consist of Pure / If pure , Element / If element similar /different Mixture Each molecule consists of compound , mono/ molecules similar/ different atoms. diatomic Sodium. similar pure One atom element monoatomic (Na) Hydrogen pure element Diatomic (H2) similar similar atoms similar pure similar atoms element monoatomic Water similar pure different atoms compound H2O different Mixture Similar pure different atoms compound molecules ELEMENTS  Element: ✘ It is a pure substance that cannot be separated into simpler substances by physical or chemical means. ✘ Each element has a unique chemical name and chemical symbol. The chemical symbol consists of one, two letters; the first letter is capitalized, and the second is lowercase. ✘ May be solid or liquid or gas. 10 Elements are not equally abundant in the universe. For example, ✘ Hydrogen makes approximately 75% of the mass of the universe. ✘ Oxygen and silicon together comprise almost 75% of the mass of Earth's crust, ✘ oxygen, carbon, and hydrogen account for more than 90% of the human body. ✘ Francium, on the other hand, is one of the least-abundant naturally-occurring elements. There is probably less than 20 g of francium dispersed throughout Earth's crust. 11  A first look at the periodic table Scientists made many trials to classify elements to ease their study. Mendeleev studies the physical and chemical properties of elements and put the first version of periodic table : 1. He organized the elements according to the similarities and masses of the elements. 2. Classified the table into horizontal rows called periods and vertical columns called groups 3. Put elements which have similar chemical and physical properties in one group. 4. He observed that the pattern of similar properties repeats from period to period. That’s why the table is called periodic table. 12 Q)Which of the following represents a compound? Explain. a. Na b. N2 c. NH3 d. H2 Compound: ✘ A compound is the combination between two or more different elements in a fixed ratio. ✘ Most matters in the universe exist in the form of compounds. Today, there are more than 50 million known compounds ✘ Q)Are the properties of a compound different from properties Of its elements ? Explain by giving example. 13 ✘ When water is broken down, its components, hydrogen and oxygen, are dramatically different than the liquid they form~ when combined. Oxygen and hydrogen are colorless, odorless gases. ✘ The opposite figure shows the elements-potassium and iodine-of the compound called potassium iodide. Note how different the properties of potassium iodide are from its elements. Potassium is a light silvery metal that reacts with water. Iodine is a black solid that changes into a purple gas at room temperature. Potassium iodide is a white salt. 14  Separating compounds into components:  However, compounds can be broken down into simpler substances.  Separating a compound into its elements often requires external energy, such as heat or electricity Groups, Video. https://www.youtube.com/watch?v=CaJzRfNIiBg https://www.youtube.com/watch?v=OHKStbYGCws&t=5s 15  Electricity H2 O2 1)Water can be separated by ………. …………into ……….and ………element Electrolysis by a process called….......................... , During electrolysis, one end of a long platinum electrode is exposed to the water in a tube and the other end is attached to a power. Negative 2) An electric current splits water into hydrogen gas at ……………pole Positive (cathode) and oxygen gas in………….. (anode) pole. 3) The volume of evolved ………..gas H2 is twice the volume of ………… O2 , Because water is composed of........... 2 H atoms and one oxygen atom. 16 17 18  ✘ States that a compound is always composed of the same elements in the same proportion by mass (Percent by mass), no matter how large or small the sample. 19 Q)If we have 2 samples of sugar (sucrose) , From the analysis, sample(1) is from granulated sugar (sucrose) its mass =20.00 gm The percent-by-mass values for the sugarcane are equal to the values sample(2) is from sugarcane(sucrose) its mass =500.00 gm obtained for the granulated sugar(for each element). So, According to the law of definite proportions, samples of a compound from any source must have the same mass proportions. (same percent by mass). We conclude that samples of sucrose will always be composed of 42.20% carbon, 6.50%hydrogen, and 51.30% oxygen, no matter their sources. 20  law of multiple proportions : states that when different compounds consist of have the same elements, different masses of one element combine with the same fixed mass of the other element in a ratio of small whole numbers ✘ Water and hydrogen peroxide The two distinct compounds water (H20) and hydrogen peroxide (H20) illustrate the law of multiple proportions. ✘ Each compound contains the same elements (hydrogen and oxygen) But Water is composed of two atoms hydrogen and one atom oxygen. And Hydrogen peroxide is composed of two parts hydrogen and two parts oxygen. So, Hydrogen peroxide differs from water in that it has twice as much oxygen. When you compare the mass of oxygen in hydrogen peroxide to the mass of oxygen in water, you get the ratio 2:1. CuCl & CuCl2 (Compounds consist of the same elements (Cu and Cl) Do they have the same percent by mass for each element? Q)How can you say that the compounds are different? As the two copper compounds must be different because they have different percents by mass. Compound I is composed of 64.20% copper, but Compound II contains only 47.27% copper. 22  Chemistry is a science that studies……………. all about the the Matter’s composition , its A properties and B changes, the reactions of different substances behavior of matter. studying living extraordinary properties C organisms D Of the substances Q2) Explain why the study of chemistry should be important to everyone.. Bec, Chemistry is the study of matter, and everything is made of matter THANKS! Any questions?  CHEMICAL LABORATORY Chemical exp. requires safety precautions , source of water , a source of heat (a Bunsen flame), Cupboards to store chemicals and tools, and various apparatuses as (sensitive balance , beakers ,cylinders , tools to measure PH,…………………..  1. BEAKERS -1) mixing liquids and solutions. 2) transferring a known volume of liquid 2. GRADUATED CYLINDER 1. Used to measure volume of liquids and volume of solids 3. It is more accurate than flasks.. FLASKS: 1) Conical Flask 1) Volumetric flask 1. It’s made of Pyrex glass 1) Round bottom and has a flat base. Flask 2. Used in titration 1. it’s used in preparing 1. Made of glass and processes. standard solutions has a rounded bottom 2.Used in preparation (very accurate known concentration). and distillation processes  BURETTE Known volume and conc. The burette is used to measure volume of solutions in a high degree of accuracy During titrations. Known (v) but unknown con. ? pH is a measure of how acidic/basic the matter is. The range goes from 0 to 14, with 7 being neutral. pHs of less than 7 indicate acidity, whereas a pH of greater than 7 indicates a base. The pH of water is 7  Quiz time https://quizizz.com/join/quiz/5f78fd0770b144001b0407e6/start?studentShare=true