2024 Atoms & Chemical Change Revision Run Down (2) PDF

Revision Run-Down - Chemical Change EVA Atoms and Atomic Structure Rutherford’s Model - + + - The electrons move around outside the nucleus. These electrons are...

Revision Run-Down - Chemical Change EVA Atoms and Atomic Structure Rutherford’s Model - + + - The electrons move around outside the nucleus. These electrons are negatively charged.  Rutherford’s Model - + + - The nucleus of an atom contains: Protons which are positively charged Neutrons, which have no charge, i.e. they are neutral  - + + - Atoms always have the same number of protons and electrons  - + + - So the number of positive charges is always the same as the number of negative charges, thus an atom is always _______ overall. The Atom Sub-Atomic Charge Particle Proto - ________ n ________ + Electro ________ n ________ + Neutro ________ n ________ - Let’s try an example How many protons? - - How many electrons? + How many positive charges? + How many negative charges? + What is the overall charge? - Let’s try an example - How many protons? - How many electrons? - ++ How many positive charges? + How many negative charges? + + What is the overall charge? - -  The Atom Sub-Atomic Charge Particle Positive - Proton ________ (+) Nucleus + Neutron No ________ + Charge Negative Electron ________ (-) - Key Concept: Copy this into your notebooks The Atomic Number This tells us the number of protons an atom has. For example: The atomic number for Carbon is 6, so a Carbon atom has 6 protons in its nucleus. The Atomic Number This tells us the number of protons an atom has. Since atoms always have the same number of protons as electrons, how many electrons does a carbon atom have? Try these ones Mass Number This tells us the number of ‘things’ in the nucleus. It tells us the number of protons plus the number of neutrons in a nucleus Mass Number A Magnesium atom has a mass number of 24 and an atomic number of.… What is the number of: 1. Protons = 2. Electrons = 3. Neutrons = Mass Number What is the number of: 1. Protons = 2. Electrons = 3. Neutrons = Mass Number What is the number of: 1. Protons = 2. Electrons = 3. Neutrons = Mass Number What is the number of: 1. Protons = 2. Electrons = 3. Neutrons = Electron Arrangement The electrons surrounding the nucleus are not simply moving around it. They are arranged into different energy levels Hydrogen, the simplest element looks like this: - + Helium, the next element looks like this: - + + -  Only two electrons can occupy the lowest energy level. So where does the next one go? The second energy level looks like this: - - + + + - 8 electrons can occupy this energy level The second energy level looks like this: - - - - - Nucleus - - - - - 8 electrons can occupy this energy level Once the second energy is full, electrons occupy the third energy levels - - - - - - Nucleus - - - - - Again, 8 electrons can occupy this energy level too. Once the second energy is full, electrons occupy the third energy levels - - - - - - - - - Nucleus - - - - - - - - - Again, 8 electrons can occupy this energy level  There is also a fourth energy level, but we will not worry about this right now. The electron configuration is written in a specific way - - + + + - 2,1 So the electron configuration for this atom is… - - Nucleus - - How about this one? - - - - - Nucleus - - -  How about this one? - - - - - - - - - Nucleus - - - - - - - - -  - - - - - - This one? - - - Nucleus - - - - - - - - - - If we have the number of electrons, we can draw an electron configuration. Let’s give it a try. Chemical & Physical Changes https://www.youtube.com/watch? v=37pir0ej_SE A physical change is a type of change in which the form of matter is altered but one substance is not transformed into another. A chemical change is what occurs when there is a change which results in a new substance being formed from the rearrangement of two or Activity Sort the changes below into the correct box answers Physical Chemical Change Dissolving Sugar Digesting Food Burning Wood Chewing Food Melting Ice in Tea Evaporating Water An Apple Rotting Fire Works Rusting Smashing a Plate Activity There are six observations that would allow you to infer that a chemical reaction has occurred. What are they? Activity There are six observations that would allow you to infer that a chemical reaction has occurred. Acids & Bases  Two very important kinds of chemicals that are used in many aspects of our lives are acids and bases. Acids and Bases are chemical opposites and behave in particular ways. Acids taste sour and may sting or burn on contact (think about lemon juice in a cut) Acids react with active metals to form hydrogen gas Acids turn blue litmus paper red Bases taste bitter Bases feel slippery Bases turn red litmus paper blue Examples of acids Examples of bases  Both acids and bases are corrosive when strong which causes gradual destruction of a substance by chemical reaction  Activity Put the properties and examples of acids and bases into the correct box Bases Acids Turns Blue Litmus Tastes Sour Vinegar Lemon Juice Feels Slippery Paper Red React with Metals Turns Red Litmus Bleach Toothpaste Tastes Bitter to make Hydrogen paper blue pH Scale & Indicator The pH scale is a measure of how acidic or how alkaline a solution is. A pH of 7 is neutral - neither an acid or a base. Acid = low pH ( less than 7) Base = high pH ( greater than 7)  pH 7.1- pH 1-3: pH 4-6.9: pH 7: pH 11-14: 10: Strong Weak Neutr Strong Weak Acid Acid al Base base Activity Answer the questions on the next … slides 1. Match the colour of universal indicator to the correct substance Weak Acid Red Weak Base Orange Strong Acid Green Strong Base Blue Neutral Purple Activity 2. The pH scale is numbered from 1 to 14. These numbers describe how acidic or basic a substance is. Match the substance to the possible pH below. Water pH 1 Weak Base Solution pH 14 Strong Acid pH 7 Solution Lemon Juice pH 9 Bleach pH 4 Gas Tests  There are three gas tests that you can perform tests on to identify what type of gas it is. Hydroge Oxyge Carbon n n Dioxide Hydrogen Gas Carbon Dioxide Gas Oxygen Gas  Gas Tests Gas Test Observation Makes a loud pop or Hydrogen Pop Test squeak sound Glowing splint will be Oxygen Reigniting a Splint reignited Limewater will go Carbon Dioxide Limewater Test cloudy Activity Fill in the gaps below 1. Reigniting a _________ splint is a test for ________ gas. 3. The limewater test is a test for ____________ gas. When the gas is bubbled into the limewater is will change from _______ to ________. 5. The pop test is a test for _______________ gas. When the lit splint is put in the gas, a ______ is _______. Activity Fill in the gaps below 1. Reigniting a glowing splint is a test for oxygen gas. 3. The limewater test is a test for carbon dioxide gas. When the gas is bubbled into the limewater is will change from colourless to cloudy. 5. The pop test is a test for hydrogen gas. When the lit splint is put in the gas, a squeaky pop is heard. Acid + Metal  Metal + Acid —> Salt + Hydrogen Acids react with metals to produce a salt and hydrogen gas.  Metal + Acid —> Salt + Hydrogen This is a general reaction. An easy way to remember it is M.A.S.H. The salt’s name is ‘metal-suffix’. The suffix depends on the acid used Acid Salt Suffix Hydrochloric Acid Chloride Sulphuric Acid Sulphate Nitric Acid Nitrate Acetic Acid Acetate Sodium Sodium + Hydrochloric Acid —> _______________ + Hydrogen Chloride  Activity Complete the reactions below Metal + Acid → Salt + hydrogen gas 1. Iron + hydrochloric acid → _________ + _______ 2. Magnesium + sulfuric acid → _________ + _______ 3. Sulphuric acid + aluminium → _________ + _______ 4. Sodium + nitric acid → _________ + _______ Acid + Metal Carbonate  Metal Carbonate + Acid —> Salt + Water + Carbon Dioxide If an acid is mixed with a metal carbonate, salt, water and carbon dioxide are produced. Activity Complete the reactions below Metal Carbonate + Acid → Carbon dioxide + salt + water Nitric acid + calcium carbonate → __________ + ____________ + ___________ Magnesium carbonate + sulfuric acid → __________ + ____________ + ___________ Nitric acid + magnesium carbonate → __________ + ____________ + ___________ Aluminium carbonate + sulfuric acid → __________ + ____________ + ___________ Acid + Base (Neutralisation) Acids and Bases are chemical opposites This means that, when they are mixed, they can cancel out each others’ effects. You need to use about the same volume of the acid and the base. These reactions have a general equation Acid + Base —> Salt + Water The first has an easy way to remember it. Metal + Acid —> Salt + Hydrogen M.A.S.H  The second has a clue in the reactants Acid + Metal Carbonate —> Salt +Carbon Dioxide + Water Carbonate —> Carbon Dioxide The third is known as a neutralisation reaction; it only produces salt and water Acid + Base —> Salt + Water What is the pH of water?  The trickiest part is naming the salt The name of the salt is made up of two words  The first word of the name is just the metal reactant Sodium + Hydrochloric Acid —> Sodium Chloride + Hydrogen Acid Salt Suffix Hydrochloric Acid Chloride Sulfuric Acid Sulfate Nitric Acid Nitrate Acetic Acid Acetate The second part of the name is determined by the acid. Nitric Acid + Sodium Carbonate → __________ + _______ + _______ Magnesium Oxide + _________ → Magnesium Nitrate + Water Activity Complete the reactions below Acid + Base → Salt + water Sodium hydroxide + Nitric acid → _______ + _________ Sulfuric acid + calcium hydroxide → __________ + _________ Copper oxide + Hydrochloric acid → __________ + _________ Hydrochloric acid + magnesium hydroxide → __________ + _________  Activity Complete the reactions below Acid + Base → Salt + water Sodium hydroxide + Nitric acid → sodium nitrate + water Sulfuric acid + calcium hydroxide → calcium sulfate + water Copper oxide + Hydrochloric acid → copper chloride + water Hydrochloric acid + magnesium hydroxide → magnesium chloride + water Activity Sort the changes below into the correct box Physical Chemical Change Dissolving Sugar Digesting Food Evaporating Water An Apple Rotting in Tea Chewing Food Melting Ice Burning Wood Fire Works Smashing a Plate Rusting