Percent Composition of Compounds
In this short video we'll cover the only type of question that teachers seem to ask, which is how to find the mass percentage that each element in a compound is responsible for.
Author Archives: hangtime
Percent Abundance
Most every element comes in a few different isotopes, which have different numbers of neutrons and therefore different masses. But the periodic table only tells you the average mass. What's a chemistry student to do?!
These two topics don't have much in common except that students tend to confuse them, so that's why they're together.
Guessing Ions From Periodic Table
"Guessing" isn't quite the right word. More like "know". Once again, this is something that you're going to have to learn by next week anyways, so might as well do it BEFORE the test so that... Well, you don't get points for learning something AFTER the test, do we.
Overview of Groups, Families & Brinklehoff (BrINClHOF)
Halogens, Alkalai Metals, Alkaline Earth Metals, Transition Metals, and Noble Gases: these are all annoying names you'll memorize over the next month whether you want to or not. One thing you will want to memorize, because you'll lose so many points if you don't, is BrINClHOF, the popular acronym for the diatomic gases! Yay!
This chapter shows you what everything on the periodic table means, including the families such as Alkalai Metals, Alkaline Earth Metals, Halogens, Transition Metals, and Noble Gases. It also explains how to tell which ions atoms form.
Solid vs Liquid vs Gas
In Chemistry class it's easy for teachers to get so bogged down in the details of whatever vocabulary-packed topic you happen to be studying that the "big picture" goes unnoticed: ultimately, everything in chemistry is about bouncy little magnets (atoms and molecules) either sticking together (solid) or rattling apart (liquid and gas).
Substances vs Mixtures
This isn't a super-exciting topic, but it will be on your quiz, so listen up!
These videos are an intro to chemistry. First we'll explain what the heck atoms, molecules and compounds are, then we'll explain how temperature makes a bunch of molecules decide to go from being a solid, to liquid, to gas.
Harder Chemical Equation Balancing Examples
Now that you're a master of the basics of balancing (thanks to the previous video), this video will show you a few tricks to use in more complicated situations, like equations with lots of polyatomic ions in them, and how to remember Mother Eats Peanut Butter.
How To Balance Chemical Equations
Sometimes students get confused by balancing because they don't know where to start on a problem. This video covers the basics of balancing chemical equations, as well as a few shortcuts to help you approach the problem the right way every time.
Also covered: translating chemical names into balanced reactions.
Converting Grams to Number of Atoms or Molecules
The hardest problems are the ones going from grams all the way to number of atoms or molecules. The big trick that helps the most students involves looking at it as a basic stepping stone problem with "moles in the middle", as I'll show you in this video. Also covered: a few more advanced moles problems with funky wording to give you a taste of what's to come.
Avogadro's Number (6.02 x 1023)
These mole problems get the most confusing when Avogadro's Number enters the mix: lots of scientific notation, calculators going crazy. This video will make Avogadro make sense for you, though, and it covers the common calculator mistake that's responsible for almost all of the errors students make in this type of problem.
Converting Grams To Moles
Lots of great grams-to-moles and moles-to-grams action in this one. Moles are confusing at first, but once you see it's always a one-step problem, it gets nice and repetitive (and that's a good thing!). Also intriguing: what to do about molecules with crazy parentheses?
What Is A Mole?
This video covers what moles are, and how to create conversion factors for them. It also explains why your teacher is doing this "moles thing" to you, which is a question I've heard from many a frustrated chem student. Trust me, there is a reason!
Grams to moles, moles to grams, grams to number of atoms or molecules, conversions, 6.02 x 1023... Not quite stoichiometry yet, but you'll need this before you get there.
Percent Error
Rarely in science or statistics will you find a concept which is called exactly what it is. But this is it!
Not a long chapter, but one which explains something that's probably on your next lab report.
Standard Deviation & Normal Distributions
This video takes a more conceptual stab at standard deviation by showing you what's at the heart of Statistics: the "normal distribution". Also covered, perhaps the only thing you'll remember about Stats in 5 years: the 68-95-99.7 Rule.