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What is the ionization constant? The ionization constant is a factor you have to take into account when you talk about splitting apart chemicals. Mostly, the ionization constant has to do with splitting apart ionic compounds. It is estimated by the number of ions you get after you break apart a chemical. While in truth, it is a little more complex than that we will go into. We will not go into that complexity here. What is the ionization…

What sections should I know before attempting to learn this section? —> Introduction to Units —> Unit Prefixes —> Introduction to Problem Solving   How do you convert from one scientific unit to another? Conversions are taking a number (quantity) with units and changing the number to represent a new set of units. We use these unit conversions in every day life. Whenever you buy more than one item in a store, you…

What is the lesson about? Solutions are a mixture of two or more things. In this lesson, you will learn about how chemistry defines mixtures, how it measures those mixtures, and how those mixtures behave as something different from each of their individual components. We live in a world of solutions and so this lesson helps you define how to analyze the solutions around you.   Why is it critical to understand? Most of the lesson hinges on…

  How do I tell the difference between metal and non-metal elements? One important division (organization) of the periodic table that I want to discuss is what is called the metals versus the non-metals. For an example of a periodic table that shows this click here. Keep this periodic table open as you read this and do practice problems. If you look toward the right side of the periodic table you just opened, you will notice that elements…

How do you form an equilibrium equation from a chemical equation? Now let us see how we apply this equilibrium equation to a chemical equation. It is usually best to see examples first and explain after.   Group 1 Examples: Set up the equation for the equilibrium constant. VIDEO Setting up the Equation for the Equilibrium Constant Examples 1. N2(g) + 3 H2(g) <—-> 2 NH3(g) K = [ NH3 ]2 [ N2 ] [ H2 ]3 1 1 1 2 H2O(g)…

What is pressure? The scientific definition of pressure is force divided by area. Again this definition is not that great for giving you an idea of how to think about pressure. Luckily humans have built in experience with pressure so I will use that as an example. We measure the pain we feel in terms of pressure. The higher the pressure the more painful the lower the pressure the less painful. So if you put your whole hand on a table and push…

  How do electrons move between shells or energy levels? VIDEO Explanation of electrons moving between shells. With all this information about the position of the electrons compared to the nucleus in sections like electron shells and energy levels , we should also discuss how electrons can move from one shell or energy level to anther. In these next few sections I will use the words electron shells and energy levels to mean that same…

How do you convert between Kc and Kp? Another problem you might come across is how to convert between Kp and Kc. That is to say how to convert between the equilibrium constant from pressure units and the equilibrium constant from concentration units. The formula is below.   Kp = Kc (RT)Δ n   Above the symbols represent: Kp is the equilibrium constant for pressure Kc is the equilibrium constant for molar concentration R is our old…

What is gas stoichiometry? In this section you are going to put to use a lot of the previous information you have learned in this lesson. You are also going to combine the information from the gas laws lesson with other sections like calculating the molar mass of compounds and combining stoichiometry and molar mass conversions. Make sure you have gone over or know these past sections before you enter this section. One new item that we need to…

What sections should I know before attempting to learn this section? —> Covalent, Ionic, and Metallic Bonds —> Forming Ionic Compounds —> Breaking Apart Ionic Compounds   How do you use an ionic name to create the ionic compound? Going in the other direction (taking the name and making the ionic compound), however, is a littler harder. First, you have to find the charges of the elements, and then you have to get…

What is the lesson about? This lesson is about how the numbers of chemistry are read and written. The reason that they are different from other non-scientific or non-mathematical number is because many numbers in science are either very small or very large. They also help us to make quick estimations if needed.   Why is critical to understand? From here on out many of the numbers in chemistry will be written in the format that you see in…

How do you relate volume and pressure to Le Chatelier’s Principle? The next hurdle we have to overcome is explaining pressure and volume. Remember we are not going to think about them in the same way as concentration and temperature. Also when we talk about pressure and volume we will not say that we increase the pressure or volume of the reactants side or the products side. This is chemical reaction, both the reactants and products, are…

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Element Name Symbol Atomic Number Actinium Ac 89 Aluminum Al 13 Americium Am 95 Antimony Sb 51 Argon Ar 18 Arsenic As 33 Astatine At 85 Barium Ba 56 Berkelium Bk 97 Beryllium Be 4 Bismuth Bi 83 Bohrium Bh 107 Boron Ba 5 Bromine Br 35 Cadmium Cd 48 Calcium Ca 20 Californium Cf 98 Carbon Ca 6 Cerium Ce 58 Cesium Cs 55 Chlorine Cl 17 Chromium Cr 24 Cobalt Co 27 Copernicum Cn 112 Copper Cu 29 Curium Cm 96 Darmstadtium Ds 110 Dubnium Db 105…

This is one of the most difficult lessons for most students. Make sure you put a lot of effort into this lesson.   NOTE: None of the equilibrium constants ( K ) in this lesson are the true equilibrium constants of the formula. This is also the case for the Δ H of chemical equations and the thermodynamics. I made up both the equilibrium constants and the Δ H numbers because I did not want to spend hours searching for them. The fact that I…

What is the difference between atoms, molecules, and compounds? Definitions are important to address in this lesson. At this point in chemistry, many people get confused by the words atom, molecule, and compound. An atom is the smallest indivisible part of matter. When you look at a chemical like Rb2S, 1 Rb is 1 atom. An atom is simply any single element written. So if a single element is written alone like P then it is only an atom. However,…

What sections should I know before attempting to learn this section? —> Orbitals Part 1 —> Energy Level Part 2 —> Complete Electron Configuration Part 3 —> Electron Configuration Diagram Part 5 —> Quantum Numbers Part 1 (n) —> Quantum Numbers Part 2 (L) —> Quantum Numbers Part 3 (mL ) —> Quantum Numbers Part 4 (ms )   How do we use the 4 different types of quantum…

This table is valid for the temperature 25 C Chemical Substance (state) ∆Hf ◦ (kJ/mol) Ag(s) 0 Ag+(aq) 105 AgBr(s) -100 AgCN(s) 164 AgCl(s) -128 Ag2CrO4(s) -712 AgI(s) -62 Ag2O(s) -32 Ag2S(s) -40 Al(s) 0 Al2O3(s) -1675 Al(OH)3(s) -1276 AlCl3(s) -704 Al2(SO4)3 (s) -3440 Ba(s) 0 BaCO3(s) -1220 BaO(s) -582 Ba(OH)2(s) -945 BaSO4(s) -1465 BaCl2(s) -858 Be(s) 0 BeO(s) -600 Be(OH)2(s) -903 Br2(l) 0 Br2(g) 31 Br2(aq) -3 BrF3 (g) -255 Br–(aq) -120…

  So what does the interaction of light and electrons look like? Like light, electrons are also tiny particles. In addition, they m ove like light both very quickly and tend to follow wave patterns. What this means is that the particle of light, the photon, and the electron particle can interact. When these two particles (electrons and photons) interact , it turns out to be something like a pool ( billiards ) game. The photons can knock…

How do you relate moles and concentration to Le Chatelier’s Principle? Lets start off talking about moles (concentration) since it is a little easier to think about. Let us use my favorite chemical equation as an example and explain how we analyze it with Le Chatelier’s Principle.   200kJ + N2(g) + 3 H2(g) <—-> 2 NH3(g)   If we talk about moles or concentration first there are a few ways we can phrase a…

How does radioactive decay work? Radioactive decay is part of what we have described so far in this lesson as alpha, beta, or gamma radiation or fission. Radioactive decay is just describing how elements break down into other elements. All of radioactive decay is dictated by one fac t; that each element has a favored balance between the protons and neutrons in its nucleus . It is kind of like how each game you play has an optimal number of…

What are redox or oxidation numbers? Redox comes from the combination of the word reduction and oxidation. The first thing we have to learn in this lesson is what they call the redox numbers. They are numbers that are assigned, much like ions. In fact, they mean the same thing as the ion charges but they are assigned to different elements in a slightly different way. So if I say an element has a redox number of +2, then that means the element…

WHAT IS ENTHALPY ΔH (DELTA H)? Enthalpy is simply talking about energy in the form of heat. So ENTHALPY is HEAT ENERGY. Enthalpy is represented by Δ H (Delta H).   200kJ + N2(g) + 3 H2(g) —-> 2 NH3(g) Δ H = +200 kJ/mol The above chemical reaction can be said to have a positive Δ H or is endothermic. All reactions with a positive Δ H are ENDOTHERMIC.   2 H2O(g) —-> 2 H2(g) + O2(g) + 147cal Δ H = -147 cal/mol The above…

What is temperature? VIDEO Temperature Discussion A lot of people have trouble with this definition in chemistry classes because they are given a long and complicated definition. I will give the complete definition of temperature first and then attempt to simplify it for you. What I want to point out before hand is that temperature is a measurement . Temperature is measuring the average kinetic energy of the molecules of a substance (solid,…

What sections should I know before attempting to learn this section? —> Orbitals Part 1 —> Energy Level Part 2 —> Complete Electron Configuration Part 3 —> Abbreviated Electron Configuration Part 4A   Why can electrons configurations in the D orbitals change? Some electron configurations tend to fill electrons in an odd way. These are the electron configurations that are exceptions to the rule. They…

What is Precipitation? It is the act of one substance changing state and therefore removing itself from the solution / mixture. The change of state will happen when you get a change of conditions (either a change of temperature, pressure, or having chemicals added to it). The most common way you see precipitation is when water molecules in the gas state collect into clouds and then change to liquid water in the form of rain. Your local weather…

What are significant figures? Significant figures (Sig Figs) or, as some people call them, significant numbers, are a part of science that deals with numbers you get from measuring devices like a scale or a ruler. It is a system to tell you how far you can trust your measurement numbers or to put it another way, how accurate they are. What you do for significant figures is count each place (decimal place) in any figure or number you are given….

How do you relate temperature or energy to Le Chatelier’s Principle?   200kJ + N2(g) + 3 H2(g) <—-> 2 NH3(g)   If we talk about Le Chatelier’s Principle in terms of temperature changes or energy it works much the same as concentration. I will use the same chemical equation example above to explain. The part you want to focus on for temperature or energy changes is the part in my example that says 200kJ. In…

        Example: What is the Δ n (delta n) of the equation below? N2(g) + 3 H2(g) <—-> 2 NH3(g) Answer: Δ n = 2 – 4 = -2   VIDEO Calculating the DELTA N ( Δn ) Demonstrated Example 1: What is the Δn (delta n) of the equation below? H2SO4(aq) <—–> H2(aq) + S(s) + 2 O2(aq)   Add together all of the coefficients of the products that involve (aq) or (g) phases. Answer: 1 H2 + 2 O2 = 3. (S…

  The last step we are going to address in this particular conversion map is the conversion to atoms. Converting between atoms and molecules is much easier than the steps that we have done before. However, it seems to many students because of that they get thrown off and have a difficult time. This conversion is all about how many of each element are in a particular substance. Check out the examples below for a more detailed explanation….

What sections should I know before attempting to learn this section? —> Protons and Electrons —> Neutrons —> Isotopes —> Ions   What is atomic notation? DO NOT USE THE PERIODIC TABLE as a reference in this section. When given the atomic notation you should have all the information you need and should not have to look elsewhere. So far we have been looking at the different elements on the periodic table…

  How do I find the protons and electrons of an element? Different individual elements can have different amounts of the protons and electrons. Since having different amounts of each of these can determine how different elements can interact with others , scientists have organized them into a sheet called the periodic table . The periodic table is organized first by the number of PROTONS an individual atom of each element has. For the…

What does ATE Versus ITE mean on the end of Polyatomic Ion Names? VIDEO Explanation of ATE Versus ITE on Polyatomic Ion Names In Group 1 and 2 of the polyatomic ions list we can notice that many of the polyatomic ions have a name ending in -ATE or -ITE. The -ATE or -ITE is telling the reader each ion has certain a number of oxygens. To be clear, it does not exactly tell you how many oxygens, but it gives you an idea about them. Its purpose is…

What are the different types of chemical equations? With many chemical equations you can break them down by the type of chemical equation. This helps you to predict how different chemicals will react when mixing them. The different types are below in bold with clear examples. Look at them and see what kind of patterns you can recognize. Use the periodic table or ion periodic table link if you need it.   SYNTHESIS (also known as…

How does Entropy Relate to the Moles of a Chemical Equation?     Without looking at an entropy table, are these chemical equations below increasing or decreasing in entropy (Δ S) based on the number of molecules?       2 N2O3(g) ——> 2 N2(g) + 3 O2(g)   Answer: Increasing (2 —> 5)       N2(g) + 3 H2(g) —-> 2 NH3(g)   Answer: Decreasing (3 —> 2)  …

What is LIMITED REACTANT (REAGENT)? Many students have tremendous trouble with this section. However, it should not be so if they have studied the previous section of combining stoichiometry and molar mass conversions . The only difference between limited reactant and previous conversion sections are that limited reactant problems have 2 or more starting points . This means that you usually have to do 2 or more conversions. The same conversions…

COMBINING STOICHIOMETRY AND MOLAR MASS CONVERSIONS (MOLES TO GRAMS CONVERSIONS): Now that we are more comfortable with stoichiometry, we can combine it with our previous efforts of molar mass conversions in the how to convert between grams and moles section. This means we are going to further complicate our conversion map to include more destinations.     VIDEO Stoichiometry Conversions Demonstrated Example 3 : If you have 4 mol of O…

What sections should I know before attempting to learn this section? —> Introduction to Significant Figures —> Significant Figures Part 4 (All Zeros)   How do you multiply and divide significant figures? Multiplying and dividing significant figures will require you to give an answer that also has the correct number of significant figures. By contrast, multiplying and dividing is much more common than adding and…

  If your math is very strong you can skip this lesson.   I start off with the mathematical side of chemistry for a very specific reason. Many people struggle with this part, as I did when I first started. However, if you cannot get past this first lesson or first test without a B or A on the test you will most likely not be able to pass the second half of chemistry. For a college student (or AP student), it is critical to know early…

  By far the most important division is the metals versus the non-metals, which we just talked about. However, some people also like to talk about how the periodic table is broken up into smaller divisions. The most common ones are alkali metals, alkaline earth metals, transition metals, metalloids, halogens, noble gasses, lanthanoids, and actinoids. This periodic table is very good at showing you where they are. The alkali metals are…

What sections should I know before attempting to learn this section? —> Protons and Electrons   What are ions? Ions are charged atoms of an element. You can create a charged atom of an element by a loss or gain electrons. This is because protons are at the center of the atom and therefore cannot be lost or gained. Since electrons are on the outside of atoms they can be lost to gained. So really ions are all about the electrons ….

  What are orbitals? VIDEO Explanation of orbitals. If you look deeper into the paths that the electrons take around the nucleus of an atom you actually begin to see that some of the shapes are not circular or spherical like the Bohr model suggests. Therefore, the Bohr model we have been working with so far is not the complete story of how electrons travel around the nucleus. Because Bohr studied the hydrogen atom and because the most…

What is the lesson about? Nomenclature means naming. So this lesson is all about naming different chemical compounds. There are different ways to name different combinations of elements so the rules can get confusing.   Why is it critical to understand? That is because naming of compounds tends to be added to questions from other lessons. Nomenclature can also come in handy when we are buying food products or medicines. Most chemicals in…

How do I find the central atom of an Electron Dot Structure (Lewis Structure)? Many different teachers have many different styles for teaching this first step. I will show you the three I like most and then I will let you choose. Method 1: The easiest to teach and understand is have you memorize a list of elements. That list is; C, Si, N, P, S, O. These elements are also in priority order. So if you have covalent compound with C and P then C is…

What is this lesson about? The periodic table is a tool to organize the elements that we use in chemistry. However, there are many different ways to look at that organization. This lesson explores those different ways to look at the periodic table.   Why is it critical to understand? Once you are able to look at the periodic table in different ways, then you can also think about how to solve different kinds of problems you may see later in…

What sections should I know before attempting to learn this section? —> Introduction to Units   What are unit prefixes? In addition to the basic chemistry units, you also have the prefixes that modify the original unit. They are laid out in this table I have created below that I call the unit prefixes table. Keep this table open as you are learning and practicing through the rest of the chapter. That looks like a lot of units to…

  Next, we tackle the concept of the greatest common divisor. This is something you most likely used in math when you were working on chapters with fractions in them. The greatest common divisor is commonly used in math when you are creating fractions in the lowest terms possible. Simply put, the greatest common divisor is a number (for our purposes, only integers) that is the largest possible number you can divide into a group of two or…

What sections should I know before attempting to learn this section? —> Protons and Electrons   What is the Bohr model of the atom? The amount and arrangement of electrons around two or more different atoms are the best way to predict how they will interact. This is why electrons are talked about so extensively in chemistry. The most simplistic, yet still correct way to understand how electrons move in atoms is called the Bohr…

What sections should I know before attempting to learn this section? —> Exponents —> Scientific Notation Part 1   How do we go from a non-scientific notation number to a scientific notation number?   What happens if we go in the reverse direction? Let’s take a non-scientific notation number and turn it into scientific notation.   VIDEO Scientific Notation Demonstrated Example 3: Convert this non-scientific…