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4. Metals and Non-metals Learning Objectives By the end of the lesson, you will be able to: ☑ distinguish between metals and non-metals ☑ describe the physical and chemical properties of metals and non-metals ☑ list the uses of some metals and non-metals MINERALS AND ORES You have learnt that all materials Here is the exact text from the image:are made up of basic substances called elements, and that elements cannot be split into simpler substances by chemical methods. There are 118 known elements. Sodium, zinc, gold, mercury, iron, lead, barium and tin (metals); and hydrogen, oxygen, carbon, sulphur, chlorine, boron, neon and radon (non-metals) are some examples. Only certain unreactive elements are found free in nature. Others occur in combined states as minerals. A mineral is a solid inorganic substance that is found in nature. A mineral deposit that can be mined and from which an element or compound can be obtained profitably is known as an ore. Elements can be broadly classified into two groups—metals and non-metals. Table 4.1 Some common ores Fig. 4.1 Some common ores a. Bauxite (aluminium) b. Malachite (copper) c. Haematite (iron) d. Galena (lead) e. Apatite (phosphorus) f. Quartz (silicon) -- --- METALS All except 20 of the known elements are metals. Most metals are reactive; they combine with other elements in nature, such as oxygen and sulphur, and occur as oxides, sulphides and carbonates. Only a few unreactive metals like gold, silver and platinum are found as free metals in the Earth's crust. Physical Properties of Metals Metals are solids at room temperature, except mercury, which is a liquid at room temperature (Fig. 4.2(a)). They are generally hard and strong, with a few exceptions such as sodium and potassium, which are soft and can be easily cut with a knife (Fig. 4.2(b)). They have a metallic lustre (shine), especially when freshly cut. They have high melting and boiling points, with a few exceptions like sodium, potassium and mercury. They are good conductors of heat and electricity. Silver and copper are the best conductors of electricity, followed by gold and aluminium. Metals are sonorous. They produce a ringing sound when struck. Most metals have high tensile strength. They can take heavy loads without breaking. They are malleable. Metals, with exceptions like sodium and potassium, can be beaten into thin sheets and foils. They are ductile. Metals, with exception like sodium and potassium, can be drawn into wires. Most metals have high density. However, sodium and potassium have low density and float on water. Fig. 4.2 Special metals a. Mercury b. Sodium --- Chemical Properties of Metals Reaction with oxygen Metals react with oxygen under different conditions to form basic oxides. These basic oxides react with water to form bases. Sodium and potassium react vigorously with oxygen at room temperature. 4Na + O_2 \rightarrow 2Na_2O To prevent this oxidation, sodium and potassium are stored under kerosene. Magnesium reacts with oxygen only when ignited. It burns with a dazzling bright flame and forms a white powder of magnesium oxide. 2Mg + O_2 \rightarrow 2MgO Copper and iron react with oxygen only when heated to a very high temperature. 2Cu + O_2 \rightarrow 2CuO --- --- Reaction with water Metals react with water to form hydroxides or oxides, along with hydrogen. Different metals react at different temperatures. Sodium, potassium, and calcium react with cold water to form hydroxides. 2Na + 2H_2O \rightarrow 2NaOH + H_2 Magnesium Reacts with steam or hot water to form magnesium oxide. Mg + H_2O \rightarrow MgO + H_2 Aluminium Forms an oxide too, but this oxide forms a protective covering over the metal and prevents further reactions. 2Al + 3H_2O \rightarrow Al_2O_3 + 3H_2 Zinc Reacts only with steam. Zn + H_2O \rightarrow ZnO + H_2 Iron Reacts with steam when heated strongly. 2Fe + 3H_2O \rightarrow Fe_3O_4 + 3H_2 Copper, gold, silver, and platinum do not react with water at all. --- Activity 4.1 Teacher Demonstration Aim: To study the reaction of metals with water. [Caution: This activity should be demonstrated by the teacher, and students should stand away from the table.] Materials required: Two 200 mL beakers Pieces of sodium and calcium Forceps Knife Litmus papers Water Method: 1. Fill each beaker with 100 mL of water. 2. Using forceps and a knife, cut a small piece of sodium. 3. Dry it on a tissue paper and drop it into one of the beakers. 4. Repeat the same procedure with calcium. 5. Test the water in both the beakers with red and blue litmus papers. Observations and Conclusions: Sodium reacts vigorously and may explode. A gas is also released. The reaction with calcium is quick, though not as vigorous as that with sodium. In both cases, the red litmus paper turns blue, showing that the solutions are bases. --- Reaction with dilute acids Most metals react with dilute acids to form their salts and liberate hydrogen gas. The reaction with reactive metals like sodium, potassium, and calcium is violent. Magnesium, aluminium, zinc, and iron do not react violently. Mg + 2HCl \rightarrow MgCl_2 + H_2 Copper, silver, gold, and platinum do not react with dilute acids. --- Reaction with bases Only some metals such as aluminium and zinc react with strong bases like sodium hydroxide to liberate hydrogen gas. Zn + 2NaOH \rightarrow Na_2ZnO_2 + H_2 --- Activity 4.2 Aim: To study the reaction of metals with dilute hydrochloric acid. Materials required: Sandpaper Six test tubes Dilute hydrochloric acid Strips of magnesium, zinc, iron, tin, lead, and copper Method: 1. Clean the metal strips with sandpaper. 2. Add dilute hydrochloric acid to the six test tubes. 3. Insert a strip of metal into each test tube. Observe if any bubbles are formed in the test tubes. If no bubbles are seen, warm them gently in a beaker of hot water. 4. Observe the speed at which gas is generated. This gives an idea of the speed of the reaction. 5. Classify the metals in order of their reactivity with dilute hydrochloric acid. [Caution: Acids are corrosive and should be handled carefully.] --- Activity 4.3 Aim: To study the reaction of metals with bases. Materials required: Small piece of zinc Beaker Sodium hydroxide Method: 1. Prepare warm sodium hydroxide or caustic soda solution. 2. Drop the piece of zinc into it. Observations and Conclusions: You will notice that zinc reacts with sodium hydroxide to liberate hydrogen gas. Observations on Metals with Dilute Acids Metals like sodium, potassium, and calcium react violently with dilute acids to liberate hydrogen gas. Magnesium, aluminium, zinc, and iron also displace hydrogen from dilute acids, but the reaction is not violent. Metals such as copper, silver, gold, and platinum do not displace hydrogen from dilute acids. --- Activity Series of Metals The activity series of metals is the arrangement of metals in decreasing order of reactivity. The series in the book shows reactivity decreasing from top to bottom. Potassium is the most reactive metal while gold is the least reactive. --- Displacement of a Metal by Other Metals A more reactive metal displaces a less reactive metal from its compounds in an aqueous solution. Some examples: Mg + CuSO_4 \rightarrow MgSO_4 + Cu Zn + FeSO_4 \rightarrow ZnSO_4 + Fe Iron can displace copper from copper sulphate solution (as shown in Activity 4.4). The solution turns green, and reddish-brown copper deposits on the iron nail. Copper cannot displace iron from iron sulphate solution, showing that copper is less reactive than iron. Cu + FeSO_4 \rightarrow \text{No reaction} Question: What do you think will happen if you place a silver spoon in copper sulphate solution? --- Activity 4.4 - Displacement Reaction Aim: To study a displacement reaction. Materials Required: Test tube Iron nail Copper sulphate solution Method: 1. Fill the test tube with copper sulphate solution (blue in colour). 2. Place the clean iron nail in the solution. Observations and Conclusions: After about an hour, the solution changes to green, and a reddish-brown deposit is formed on the iron nail. --- Corrosion of Metals Corrosion is the destruction or damage of a material due to chemical reaction. Rusting of iron happens when iron is exposed to moist air, forming a reddish-brown layer of rust. Rust is iron oxide, which eventually flakes off, damaging the object. Definition written on the page: "Slow eating of a metal’s surface due to oxidation is called corrosion of metals." --Observations on Metals with Dilute Acids Metals like sodium, potassium, and calcium react violently with dilute acids to liberate hydrogen gas. Magnesium, aluminium, zinc, and iron also displace hydrogen from dilute acids, but the reaction is not violent. Metals such as copper, silver, gold, and platinum do not displace hydrogen from dilute acids. --- Activity Series of Metals The activity series of metals is the arrangement of metals in decreasing order of reactivity. The series in the book shows reactivity decreasing from top to bottom. Potassium is the most reactive metal while gold is the least reactive. --- Displacement of a Metal by Other Metals A more reactive metal displaces a less reactive metal from its compounds in an aqueous solution. Some examples: Mg + CuSO_4 \rightarrow MgSO_4 + Cu Zn + FeSO_4 \rightarrow ZnSO_4 + Fe Iron can displace copper from copper sulphate solution (as shown in Activity 4.4). The solution turns green, and reddish-brown copper deposits on the iron nail. Copper cannot displace iron from iron sulphate solution, showing that copper is less reactive than iron. Cu + FeSO_4 \rightarrow \text{No reaction} Question: What do you think will happen if you place a silver spoon in copper sulphate solution? --- Activity 4.4 - Displacement Reaction Aim: To study a displacement reaction. Materials Required: Test tube Iron nail Copper sulphate solution Method: 1. Fill the test tube with copper sulphate solution (blue in colour). 2. Place the clean iron nail in the solution. Observations and Conclusions: After about an hour, the solution changes to green, and a reddish-brown deposit is formed on the iron nail. --- Corrosion of Metals Corrosion is the destruction or damage of a material due to chemical reaction. Rusting of iron happens when iron is exposed to moist air, forming a reddish-brown layer of rust. Rust is iron oxide, which eventually flakes off, damaging the object. Definition written on the page: "Slow eating of a metal’s surface due to oxidation is called corrosion of metals." Uses of Metals (Continued) Aluminium Used in high-voltage electric lines. Alloys like duralumin and magnalium are used in aircraft and automobile bodies. Used for making aluminium foil and cooking utensils. Copper Good conductor of electricity → Used in electrical wires, cables, motors, and transformers. Good conductor of heat → Used in the bottoms of stainless steel vessels. Zinc Used to make corrosion-resistant galvanised iron (GI) pipes and sheets. Used as an electrode in dry cells. Other Metals Gold and silver → Used in jewellery. Lead → Used in electrodes of lead storage batteries (used in automobiles and inverters). Chromium → Used for electroplating iron to give a shiny, corrosion-resistant finish. --- Looking Back (True/False Statements) 1. Gold, silver, and platinum are found in the Earth’s crust as free metals. → True 2. Most metals are solids that are soft. → False 3. Metals such as zinc and magnesium react with dilute acids to liberate oxygen. → False 4. A less reactive metal displaces a more reactive metal from its aqueous solution. → False 5. The chemical name of rust is zinc oxide. → False (Rust is Fe₂O₃.xH₂O) 6. Coating zinc objects with iron is called galvanising. → False (Galvanising is coating iron with zinc) Non-Metals Physical Properties of Non-Metals Exist as gases or solids at room temperature (except bromine, which is liquid). Not as hard as metals (except diamond, which is very hard). Low tensile strength and low density. Low melting and boiling points (except graphite). Not sonorous (do not produce a ringing sound). Not malleable or ductile (cannot be beaten into sheets or drawn into wires). Do not have lustre (except iodine and graphite). Bad conductors of heat and electricity (except graphite, and silicon under specific conditions). --Chemical Properties of Non-Metals Reaction with Water Most non-metals do not react with water. Highly reactive non-metals (e.g., phosphorus) catch fire in air, so they are stored in water. Fluorine, chlorine, and bromine react with water to form acids. Reaction with Oxygen Non-metals react with oxygen to form acidic or neutral oxides. Carbon and sulfur react with oxygen to form acidic oxides, which dissolve in water to form acids. Some oxides (e.g., CO, N₂O) are neutral and do not form acids. Examples: Carbon + Oxygen → Carbon Dioxide (CO₂) CO₂ + Water → Carbonic Acid (H₂CO₃) Sulfur + Oxygen → Sulfur Dioxide (SO₂) SO₂ + Water → Sulfurous Acid (H₂SO₃) Reaction with Acids Unlike metals, non-metals do not replace hydrogen in acids. Silicon reacts with hydrofluoric acid (HF). --Uses of Non-Metals Hydrogen Used in the manufacture of ammonia and industrial chemicals. Used in vanaspati (a cooking oil). Oxygen Used in breathing support systems in hospitals. Used with other gases in equipment to weld metals. Sulphur Used in the manufacture of sulphuric acid, sulphur dioxide gas, and other industrial chemicals. Used to make pesticides for agriculture. Used in vulcanising rubber (making it harder) and in gunpowder. Nitrogen Used in the manufacture of ammonia and nitrogenous fertilisers like ammonium nitrate and ammonium sulphate. Used as an inert gas in processed food packaging to prevent rancidity. Silicon Used in making semiconductors for microchips. Silicates (oxides of silicon) are used in making glass. Other Non-Metals Phosphorus: Used in making fertilisers (superphosphates). Chlorine: Used for disinfecting drinking water. Argon: Used in welding stainless steel and filling electric bulbs. Helium: Used in balloons for meteorological observations. Neon: Used in fluorescent lights for advertisement displays
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You place a RBC (0.9%) into a 5% sugar solution. Which statement below is false? The RBC is hypotonic to the 5% solution Which is an example of a sensor in a negative homeostatic feedback loop? Chemoreceptor in carotid body For membrane fluidity experiment, the part of the experiment that actually validated that the membrane was fluid was: The labeled antibodies of the human and mouse intermixing An example of primary active transport would be a protein requiring ATP to transport sodium ions across the plasma membrane. True If a red blood cell is put in a solution and it hemolyzes, then the solution is considered to be: Hypotonic If your body temperature goes too high you can denature enzymes in your body. True What does an integrator do in a homeostatic pathway? Measures the signal coming in to a set point and send a signal out to the body Which of the following represents stages of the cell division (mitosis) in the proper sequence? Prophase, metaphase, anaphase, telophase Which is not true for proteins? They are comprised of mostly cellulose What would be a disturbance for blood glucose homeostasis (normal blood glucose set point = 77mg/dL)? A permanent decrease in insulin production from the Islets of Langerhans Dr. Bio measures your total cholesterol and he reports back to you that your level is 300 mg/ 100 ml of plasma. You do what? Eat more oatmeal and flax to increase your HDL level. How do you make an unsaturated fatty acid? Perform a dehydration synthesis reaction on a saturated fatty acid Which is false for antioxidants? They speed up reactions in your body Which molecules do not dissolve in water? Non-polar Which molecule requires a transport protein to get through the plasma membrane (either channel or carrier protein)? Two of the answers are correct Interphase is considered to be part of normal cell division (mitosis). False What is the function of ATP? All of the answers are correct What are the three kinds of lipids? Triglycerides, phospholipids, and steroids When glycerol combines with 3 fatty acids to form a triglyceride (fat), which of the following chemical reactions has occurred? Dehydration Synthesis How can you alter a protein’s shape? More than one answer is correct If a red blood cell is put into a solution and it maintains its shape, then the solution is considered to be: Isotonic Which molecule requires some type of transport protein to get through the plasma membrane? Sodium Ion Cofactors are molecules that activate enzymes. Which is not a cofactor? Mercury The nitrogenous bases found in DNA have complementary paring. Which pair is correct? C-G Which is not true for meiosis? Results in a gamete that is 2N In the diagram below the two solutions are separated by a semi permeable membrane. In which direction will net movement of water occur? From side A to side B Which is not a component of a DNA molecule: Ribose Sugar Phospholipids are similar to fatty acids except for? Phospholipids have a phosphate group Which is not true for cells? They allow diffusion of all molecules If you combine a molecule of glucose and fructose, which statement is true? You have formed sucrose Which is true for enzymes? Activity will increase until the enzyme becomes saturated What method would you use to get glucose into a cell along/down it’s concentration gradient (from high to low)? Facilitated Diffusion Which is not considered an integrator in a negative homeostatic feedback loop? Pancreas Which phase of the cell cycle is where cytokinesis takes place? Telophase What vitamin do we produce by sitting in the sun; it aids in calcium absorption from the small intestine? Vitamin D Why is it important to think about ion dissociation in the body? All the above In what order do you use macromolecules for fuel? Carbohydrates, lipids, proteins Which is false for cholesterol? It can dissolve in water/blood You place a RBC (0.9%) into a 0.5% sugar solution. Which statement below is false? The RBC is hypertonic to the 0.5% solution Which is not a membrane protein function? Protein synthesis Ingesting (eating) excess hydrophilic vitamins, such as vitamin C, results in excess vitamin C being stored in your tissues. False Diffusion is: The movement of molecules from an area of high molecular concentration to an area of low molecular concentration across a selectively-permeable membrane The hormone responsible for glucose uptake/removal from the blood is: Insulin What method would you use to get sodium ions into a cell against sodium’s concentration gradient (from low to high concentration)? Active Transport Which phase of the cell cycle is where the cell is functioning normally or doing its job? Interphase Evidence for mitochondria once being bacteria that our cells engulfed is: It has it’s own DNA Ionic molecules (ie NA+, K+) can diffuse straight through the plasma membrane. True What is the difference between cis and trans fatty acids? Cis fatty acids have hydrogens on the same side of the carbon double bond and trans fatty acids do not Cofactors are molecules that activate enzymes. Where do we get cofactors from? Vitamins found in fruits and vegetables RNA has what nitrogenous base in place of thymine? Uracil Large polar molecules (ie glucose) can diffuse straight through the plasma membrane? False Which lipoprotein is comprised of more protein and less cholesterol so it scavenges for cholesterol in the blood? High density lipoprotein A normal human being has 46 chromosomes (23 pairs/2N/diploid) in each somatic cell (body cell). True The three main compounds digested by the digestive system are? Fats, carbohydrates, and proteins Meiosis is the process in which our sex cells go from 46 chromosomes to 23 single chromosomes. True The effector in any negative feedback loop is usually: An organ/tissue If a red blood cell is put into a solution and it crenates (shrinks), then the solution is considered to be: Hypertonic Which statement is false for glycogen? It is a disaccharide Enzymes aid in digestion by? Lowering the energy required to break food apart Nonpolar molecules (ie CO2) can diffuse straight through the plasma membrane
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**Properties of Matter** - **Physical vs Chemical Properties** - *Physical Properties:* Can be observed without changing the substance (e.g., color, density, melting point, boiling point) - *Chemical Properties:* Describe a substance’s ability to undergo chemical changes (e.g., flammability, reactivity with acid) - **Examples of Each** - Physical: Ice melting, water boiling, density, solubility - Chemical: Rusting iron, burning wood, tarnishing silver - **Intensive vs Extensive Properties** - *Intensive:* Do not depend on the amount of matter (e.g., density, boiling point, color) - *Extensive:* Depend on the amount of matter (e.g., mass, volume, length) --- **Density** - **Definition, Units, and Formula** - Density (ρ) = Mass (m) / Volume (V) - Units: g/cm³ (solids), g/mL (liquids), kg/m³ (gases) - **Comparison of Densities** - Solids: Generally highest density - Liquids: Lower density than solids but higher than gases - Gases: Lowest density - **Solid: Regular vs Irregular Shape** - *Regular Shape:* Use geometric formulas to find volume - *Irregular Shape:* Use water displacement method - **Factors Affecting Density** - Temperature (increase decreases density for most substances) - Pressure (affects gases significantly) - Composition (different materials have different densities) --- **Elements, Compounds, and Mixtures** - **Matter: Definition and Examples** - Anything that has mass and takes up space (e.g., air, water, rocks) - **Pure vs Impure Matter** - *Pure:* Elements and compounds (e.g., oxygen, water) - *Impure:* Mixtures (e.g., saltwater, air) - **Atom vs Element** - *Atom:* Smallest unit of an element - *Element:* Substance made of one type of atom - **Compounds vs Mixtures** - *Compounds:* Chemically bonded elements (e.g., H2O, CO2) - *Mixtures:* Physically combined substances (e.g., salad, air) - **Types of Mixtures** - Homogeneous (solutions, uniform throughout) - Heterogeneous (distinct parts, not uniform) - **Examples of Mixtures** - Homogeneous: Saltwater, air - Heterogeneous: Salad, granite --- **Solubility** - **Solutions** - *Parts:* Solute (dissolved substance) + Solvent (dissolving substance) - *Examples:* Saltwater (solute: salt, solvent: water) - **Effect of Temperature and Pressure** - Higher temperature increases solubility of solids in liquids - Higher pressure increases solubility of gases in liquids - **Gases vs Liquids** - Gases dissolve better in cold liquids under high pressure - Liquids dissolve better at higher temperatures - **Gaseous, Liquid, and Solid Solutions** - Gaseous: Air (oxygen in nitrogen) - Liquid: Saltwater (NaCl in H2O) - Solid: Alloys (brass, steel) - **Concentrations** - Unsaturated: Can dissolve more solute - Saturated: Maximum solute dissolved - Supersaturated: Holds more than normally possible - **Solubility Curve** - Shows solubility vs temperature - Higher points indicate higher solubility --- **The Mole** - **Avogadro’s Number** - 6.022 x 10^23 particles per mole - **Molar Mass** - Mass of one mole of a substance (g/mol) - **Particle, Mass, and Mole Calculations** - Particle calculations: Using Avogadro’s number - Mass calculations: Converting between grams and moles - Mole calculations: Determining amount of substance - **Moles at STP (Standard Temperature and Pressure)** - 1 mole of gas = 22.4 L at STP - **Atomic Mass Units (AMU)** - Unit for atomic/molecular mass --- **Labs** - **Density Lab** - Measure mass and volume, calculate density - Compare densities of different materials - **Elements, Compounds, and Mixtures Lab** - Classify substances based on their properties - **Mystery Powder Lab** - Identify unknown substances using solubility and reactions - **Cornstarch Lab** - Explore properties of non-Newtonian fluids This guide covers essential concepts in matter, density, solubility, and the mole, along with relevant lab activities
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Ch 2 Chemical Compounds and Bondings Chemical bond: force of attraction between 2 atoms or 2 ions. There are 2 main types of chemical bonds: 1. Ionic bond: a bond between a metallic atom (metal) and a non-metallic atom (non-metal) in which there is a complete transfer of electrons from the metal to the non-metal. The compound which is formed is called an ionic compound. Ex.: NaCl , MgCl2, Al2O3 To write the formula of an ionic compound we use the criss-cross method (we down cross multiply the charges without the sign, only the numbers of the charges) Remark: if the charges are the same then they cancel each other in the formula so there will be one atom of the metal and one atom of the non-metal in the compound. Exercise: Write the formula of the compound which is formed between the following elements, and name each compound. a) Rb and S: b) Ca and Se: c) Al and Br: d) Na and N: - Draw a Bohr diagram to show the transfer of electrons (loss / gain) in an ionic compound. Example: Na2O (sodium oxide) Remark: The ionic bond is also described as an electrostatic force of attraction between a positive ion and a negative ion (eg: Na+ Cl- ). 2. Covalent bond: a bond between a non-metal and another non-metal in which there is a sharing of electrons between the non-metallic atoms. The compound that is formed is called a covalent or molecular compound. Molecule: 2 or more atoms (non-metallic) bonded together; the atoms can be of the same element such as O2 or of different elements such as HCl, CH4, H2O,….. We show the sharing of electrons between non-metallic atoms by using the Lewis diagram. In addition we can make intersecting circles for the atoms to show the sharing. Reminder: Lewis diagram of an atom shows only the valence electrons of that atom. Most of the atoms follow the octet rule (there are very few exceptions), that is each atom will have eight electrons in the valence shell (same as noble gases) except hydrogen will have 2 electrons after sharing (same as helium). Remark: 2 electrons that are not bonded to any other atom is called a lone pair (non-bonding pair) of electrons. Exercise: Draw lewis diagrams to show the sharing of electrons in each of the following compounds: 1. NF3 2. CH4 3. CO2 4. CCl4 5. CH2O Remark:In drawing Lewis structure, we show the bonds between the atoms and we also show all lone pairs (if present) on any atom. - Naming molecular compounds: 1: mono 2: di 3: tri 4: tetra 5: penta 6: hexa 7: hepta 8: octa 9: nona 10:deca Example: PCl5 : phosphorus pentachloride Remark: If the first element contains only one atom we don’t write mono before it; If the second element contains only one atom we have to write mono before it. Ex.: NO : nitrogen monoxide CO: carbon monoxide Exercise: Fill in the table below Name Chemical Formula diphosphorus pentoxide SO3 CO Aluminum sulfide Al2S3 SF6 Calcium oxide Lithium nitride Li3N Remark: If the compound contains a transition metal, then we have to mention the type of charge of the transition metal by inserting a roman numeral in brackets (I, II, III, IV ….) after the symbol of the transition metal. Example: Name the following compounds: - FeCl2 : Iron (II) chloride - Cu(NO3)2 : Copper (II) nitrate Remark: There are few transition metals that have only one type of charge such as zinc, nickel, and silver; in this case no roman numeral is required. Zinc : Zn+2 Silver: Ag+ Nickel: Ni+2 - ZnSO4 : zinc sulfate - AgNO3 : silver nitrate - CuSO4 : copper (II) sulfate - Co(NO3)3 : cobalt (III) nitrate Exercise: Write the formula of the following compounds. Calcium phosphate: Iron(III) hydroxide: Sodium hydroxide: Manganese(II) hydroxide: Barium sulfate: Zinc carbonate: Ammonium nitrate: Remark: We must enclose the polyatomic ion in brackets if the number after it is more than 1. Note: If the polyatomic ion that ends with the prefix –ate decreases by one oxygen atom then the prefix changes to -ite. If the prefix ending with – ite decreases by one oxygen atom then we precede the prefix by hypo, whereas if the prefix ending with – ate increases by one oxygen atom then we precede the prefix by per. Example: ClO3- is called chlorate; if we reduce one oxygen atom then the ion becomes ClO2- and is called chlorite, however if we increase by one oxygen atom then the ion becomes ClO4- and is called perchlorate; and if the chlorite is reduced by one oxygen atom then the ion becomes ClO- and is called hypochlorite. Exercise: Name the following compounds: K2SO3 : NaNO2 : Mg(ClO4)2 : LiBrO2 : - Comparison Table between ionic and covalent (molecular) compounds: property Ionic Compounds Covalent Compounds State (at room temperature) solids Solids, liquids or gases Melting point and boiling point Very high Usually low Involvement of electrons Loss and gain (transfer) of electrons Sharing of electrons Electric conductivity When dissolved in water (in solution) , electric conductivity is high
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