Please enable JavaScript.

Coggle requires JavaScript to display documents.

Chemistry Unit 4 - Coggle Diagram

- - - - Empirical formula: The empirical formula of a substance is the ratio of atoms that are in a particular molecule. However, this formula does not indicate the real formula because the real formula may be a multiple of the empirical formula (Empirical formula is just a ratio of the atoms.) C2O4 can be expressed as CO2 in empirical formula terms.
      - Molecular formula: It is the actual formula of the molecule, and it shows not only the ratio of the substances that make up the molecule but also how many, like ‘C2O4’ would just be C2O4 in molecular formula terms.
      - Main idea: Using the amount of measured masses can be used to determine the empirical formula, since then you’d have a ratio of all of the substances. However, it would just be an empirical formula because just using the masses of the elements cannot tell anything other than the ratio in which they exist in.
      - Words to remember: empirical formula, molecular formula
    - - Main idea: Calculating empirical formulas from the known mass of how much of each atom can be found in a molecule, and then dividing through by their molar mass. Then, divide all numbers by the smallest number and that is how many atoms of a particular kind can be found in a molecule (or at least the ratio.)
    - - Main idea: The molecular formula will always be some kind of multiple of the empirical formula, so to calculate molecular formula from empirical formula using percentage composition and molar mass, first see what the molar mass of the empirical formula of the substance is, then divide that number from the molar mass of the actual substance.
  - - - Averaging the Mass of Different Objects
        
        Main idea: If the ratio of the sample masses is the same of the ratio of the masses of the individual components that make up those masses, then there will be the same number of components in each sample.
        
        Words to remember: components, sample mass
        
        Components: Something, whether a part or an element, that makes up the whole system/larger object
        
        Sample mass: The weight of a sample
      - A Closer Look
        
        Main idea: This law of the same ratio of sample masses and individual components also applies to other molecular things, like atoms.
      - Averaging the Mass of Similar Objects
        
        Main idea: Objects don’t need to have identical masses and then can be counted by weighing all of them separately, just that you need to know the average and then multiply by how many objects there are to the average to find the total weight.
        
        Words to remember: identical, average, mass
        
        Identical: similar in every detail, exactly alike in mass, volume, etc.
        
        Average: in this way, it means the mean of the numbers, where you add all of the numbers and divide by how many numbers there are in total
        
        Mass: The amount of matter that some system or object contains
    - - Amu: Atomic mass unit. It is also more specifically known as 1.66*10^-24 grams
      - Average atomic mass: The average mass of a particular atom, which has to be calculated considering that there are isotopes that have a different amount of occurrences on Earth
      - Isotopes: They are different types of the same element that have the same number of protons but not the same number of neutrons. They have a different weight than the normal atom in its regular form.
      - Words to remember: amu, average atomic mass, isotopes
      - Main idea: Averaging is useful in the atomic world because taking the average of the atomic mass of the same kind of atoms results in a mass (average mass) for the atom, which can be used to calculate the weight of molecules that the atom is in.
    - - Defining the Mole
        
        Main idea: Avogadro’s number, or the mole, is 6.022*10^23 of anything, whether it’s atoms, seconds, or other such things. However, most of the time using this to talk about things in real life except on the molecular level is almost impossible to actually happen. Measuring atoms and molecules like this is sensible, however.
        
        Words to remember: mole, Avogadro’s number
        
        Avogadro’s number = mole = the number equal to how many carbon atoms in 12.01 grams of it, also known as 6.022*10^23.
      - Using the Mole + A Closer Look
        
        Main Idea: When a sample of an element is there that equals the element’s average atomic mass, then there is a mole of that element. This can be used because if a known mass but unknown amount of element is there, and the amount of atoms is needed, then use the amount of mass, divide by how much a mole of that substance weighs, and multiply how many atoms/molecules are there in a mole.
  - - - Formula weight: The same as a molar mass, but just with ions instead.
      - Molar mass: Measured in grams, it’s the mass of exactly 1 mole of any substance.
      - Words to remember: molar mass, formula weight
      - Main idea: The molar mass of any substances, which is just the mass of 1 mole of the substances, is calculated by summing the mass of the individual atoms when there’s one mole of each: for example, a mole of carbon dioxide would be like 1 mole carbon+1 mole oxygen+1 more mole oxygen
    - - Mass fraction: The mass fraction is how much mass of the element there is compared with how much mass is there in the total substance.
      - Mass percent: This is the same as mass fraction, except just expressed in a percent form instead of a fractional one.
      - Words to remember: mass fraction, mass percent, composition
      - Main idea: Finding the percent composition of a given element in a compound, just take the mass of that element if there were 1 mole of it, and then divide that by the amount of mass there would be in 1 mole of that substance
- - - - Words to remember: acid, base, hydroxide
      - Acid: An acid is something that produces H+ ions, or protons, when dissolved in water.
      - Main idea: Acids, when dissolved in water, can form H+ ions, and when bases are dissolved in water, they can form OH- ions. This shows that strong bases and strong acids, when combined in an aqueous form, can produce water.
      - Bases are substances that dissolve in water and produce OH- when dissolved in water. Hydroxides are just strong bases.
    - - Oxidation-reduction reactions, also called electron transfer reactions, can take place between a metal and a nonmetal. However, they can also happen between two nonmetals.
      - Words to remember: oxidation-reduction reactions, electron transfer reactions
      - Main idea: When a metal combines with a non-metal, and an ionic compounds forms, it is called an oxidation-reduction reaction, which is just a reaction that involved a transfer of electrons
  - - - What happens when an ionic compound dissolves in water?
        
        Ion: An ion is a substance that has a net electric charge because it does not have enough or has too many electrons.
        
        Cation: A cation is the part of a substance that is positively charged.
        
        Words to remember: strong electrolyte, ion, cation, anion
        
        Anion: An anion is the part of a substance that is negatively charged.
        
        Main idea: When an ion dissolves in water, its positive parts and negative parts are essentially separated, making some parts of the water positively charged and some negative charged.
        
        Strong electrolyte: A substance that gets entirely (meaning all of the units of the substance) broken down into cations and anions when put in water.
      - How to decide what products form
        
        Main idea: When deciding how the ions have mixed, it helps to know that a solid compound (the precipitate) must have a zero net charge, so one of the cations Then, cross out the ones that were the initial reactants, and then do research to see which could it actually be.
        
        Words to remember: net charge, precipitate
        
        Precipitate: A solid that is formed from a solution (a mixture of two or more different molecules).
        
        Net charge: The net charge of any particular substance is the overall charge of it. For example, if the net charge was -1 for something, then that means that substance is an ion with an overall charge that is negative 1.
      - Using solubility rules
        
        Words to remember: soluble (and its sister words insoluble and slightly soluble), salt
        
        Soluble: A property of a substance that the substance can be dissolved in water. Soluble substances easily dissolve in water.
        
        Main idea: Solubility rules of various compounds and seeing if two molecules will combine to form a solid matter in detecting if there will be precipitates in the final solution.
        
        Insoluble = slightly soluble = almost impossible to dissolve in liquids (mostly water), and does not dissolve much so that the difference is undetectable to the eye.
        
        Salt: It is also another word for an ionic compound, and it doesn't necessarily have to mean NaCl.
    - - Main idea: A complete ionic equation can represent the forms of the reactants and products, which can clearly show what happens in the solution.
    - - Main idea: There are sometimes driving forced that make reactants form into products, and the most common are formation of a solid, water, or gas; and transfer of electrons.
  - - - Main idea: If a formation of a solid happens, then the reaction is called a double-displacement reaction or a precipitation reaction. If formation of water occurs, it is an acid-base reaction. If transfer of electrons occurs, then it is an oxidation-reduction reaction. Finally, if a gas is formed, it is called a single-replacement reaction. The
    - - Decomposition Reactions
        
        Word to remember: decomposition
        
        Main idea: Decomposition reactions is where a compound can be broken down into simpler ones, which is sort of the opposite of synthesis reactions.
        
        Decomposition: This is the process where something decomposes, or breaks down, into other substances. In this case, it is compounds breaking into elements or simple compounds.
      - Synthesis (Combination) Reactions
        
        Main idea: Synthesis (combination) reactions is where two substances combine to form one molecule or compound. For example, 2H2+O2 => 2H2O
      - Combustion Reactions
        
        Combustion: This is just where something blows up (hence the word combustion used to define reactions that 'blowup')
        
        Word to remember: combustion
        
        Main idea: Combustion reactions produce energy so quickly that flame results from this, and combustion reactions involve oxygen.
- - - - Word to remember: mole ratio
      - Mole ratio: A mole ratio is the ratio between the amounts in moles of two or more compounds that are combined somehow in a chemical reaction.
      - Main idea: To calculate the amount of moles that could result from a reaction, like a decomposition one, then use the equation, since the ratios of the equation represent how many moles of the reactants will make moles of products.
    - - Words to remember: ratio, coefficients
      - Main idea: When there are coefficients, remember that they are just there to give pretty much the outline of the ratio of molecules used and needed to make certain amounts of products, so multiplying all of the coefficients by the same number will also make technically the same equation.
      - Coefficients: The number coming in front of the reactants and products, and they are necessary to balance out an equation.
      - Ratio: In a chemical reaction, a ratio can be used to see how many of what compound is needed to make a successful reaction. For example, if 1 CO2 and 2 H2 are needed, then the ratio of them needed is 1:2.
  - - - Word to remember: stoichiometry
      - Stoichiometry: This is the process of using a chemical equation to calculate how much reactants and products will be involved in a reaction.
    - - Main idea: Comparing two reactions is used for seeing how many moles of something will react with the same amount of two different things. For example, how many moles of HCl, or stomach acid, will react with one gram of two different types of antacid can be a comparable question.
    - - Main idea: To find out how many moles or grams of reactants will be needed in an equation that has the mass of one of the products given in grams, you need to convert the grams into moles and then find out how many moles or grams of the reactant will be needed.
  - - - Excess: If there is an excess of a molecule or compound, then there will be more than necessary for the ratio of the other compound to be fulfilled. This is the opposite of the limiting reactant.
      - Stoichiometric quantities: This is how much of the reactants are needed to ensure that exactly the correct amounts of each are used and there is no limiting reactant or excess of any compounds or molecules.
      - Words to remember: excess, stoichiometric quantities
      - Main idea: Calculations can be done involving these limiting reactants by a few steps: 1. Making sure that there is a balanced formula, 2. Converting the amount in grams to moles, 3. Figuring out how many moles of the other reactant is needed, 4. Converting to grams to get the final answer.
    - - Main idea: The amount of products expected from a certain amount of reactants will be the theoretical value, but sometimes in real life that much product does not result, hence the name actual yield.
      - Theoretical yield: How much yield is expected from the amounts of reactants used, so it is what is thought to be the amount of products. However, in real life the amount might be less than what is really expected.
      - percent yield: The actual yield divided by the theoretical yield, which is usually expressed in a percentage form.
      - Words to remember: percent yield, theoretical yield
    - - Words to remember: limiting reactant, stoichiometric mixture
      - Stoichiometric mixture: This is a mixture that has all of the relative amount of reactants in the same ratio that the given equation, so there is really no limiting reactant in the mixture.
      - Main idea: Sometimes, there is an exact number of moles necessary for a reaction to work, with no reactants left at the end. However, sometimes there is too much of one reactant and not enough of the other reactant with it. Therefore, sometimes there will be excess of one kind of reactant left in the solution.
      - Limiting reagent, or limiting reactant, is the element or compound that is less than what is needed to match the amount necessary for the ratio to be. This means that the limiting reactant is not necessarily the one that is less common, but the one that can not fulfill the ratio when all of the other reactant tries to be used.