- Introduction to chemistry
- Preparing to study chemistry
- Elements and atoms
- Average atomic mass
- Worked example: Atomic weight calculation
- The mole and Avogadro's number
- Atomic number, mass number, and isotopes
- Worked example: Identifying isotopes and ions
- Isotope composition: Counting protons, electrons, and neutrons
A summary of math and science knowledge to get you ready for learning chemistry on Khan Academy!
Welcome to the world of chemistry!
In this article, we'll summarize some fundamental concepts that will be helpful as you learn introductory or AP Chemistry. If some of the topics look unfamiliar or you don't remember them anymore, don't worry! We've provided links to help you learn or review the material on Khan Academy as you go. Remember, you can learn anything!
- Graphing slope-intercept form: Part of the fun of chemistry is running your own experiments. Once you obtain experimental data, you'll need to know how to visualize and interpret the results.
- Quadratic formula: Knowing how to set up and solve quadratic equations will come in handy when you learn about chemical equilibrium.
- Scientific notation: Chemists are lazy and don't want to write out all the zeros in numbers like 300,000,000 or 0.0000057, so we instead write these numbers using scientific notation. Understanding scientific notation will let you skip writing out all those zeros, too!
- Significant figures: Scientists use significant figures to aggravate chemistry students (just kidding!) and communicate the precision of a measurement or calculation.
Physics and biology
- The scientific method: Scientists are constantly uncovering new information about how the world works. The scientific method helps us ask questions about our observations and design experiments to test possible explanations.
- Coulomb’s law: The force between charged particles can be used to explain the properties of matter down to the subatomic level.
Want to join the conversation?
- This question has been bugging me for a while. are most of the man made elements on the periodic table a combination of other elements from the periodic tables? If so why aren't they classified as compunds?(191 votes)
- They are individual atoms of a new element. Compounds are two or more atoms chemically bonded into a molecule.(214 votes)
- Does every element have an isotope(s)(37 votes)
- can you please tell me what makes acids acid and bases base. what is special in them(0 votes)
- There are several definitions to acids and bases, all of which were created relatively at the same time. The Arrhenius theory states an acid donates a hydronium ion/proton(H+) and a base donates a hydroxide (OH-) subsequently increasing the concentration of each in a solution. The Bronstead-Lowry definition states an acid and base react to form their conjugate base and conjugate acid conterparts with the exchange of a proton (H+). Finally, the most emcompassing definition comes from Lewis theory. It states an acid is one that accepts electron pair (i.e. an electrophile) and a base is one that donates an electron pair (i.e. a nucleophile). This a very simiplified explanation for these definitions.(23 votes)
I am 10th grade student and I do not have any basic knowledge of chemistry
I realised that there are no high school chemistry course in khan academy unlike physics
Will you recommand me to study with chemistry library or Organic chemistry?(9 votes)
- If you’re beginning a study of chemistry with no prior exposure to it before, I would begin with the chemistry library on KA first. It begins with the fundamental concepts. The chemistry library is essentially equivalent to high school chemistry. The AP chemistry section would be the next step up in complexity. But there are some topics which are more fully explained in the AP chemistry section compared to the chemistry library so the best strategy would be to mainly rely on the chemistry library, but check out the AP chemistry section when needed.
I would also recommend only beginning organic chemistry after you’ve completed the AP chemistry section. Organic chemistry is one step more complicated than AP chemistry.
Hope that helps.(22 votes)
- What is an easy way to memorize the Periodic table of elements?(8 votes)
- Ummm. Hi. What helps me is repeating... Even if It's over and over again. Also write it down, writing is always a good way to help memorize certain material... :)(10 votes)
- Hi, can you please explain the last sentence?
Coulomb’s law is a mathematical relationship which describes the amount of force two charged objects exert on each other. Charged objects being objects with either a negative or positive electric charge. In a chemistry context we can understand this as atom having unequal amounts of protons and electrons, since those particles are responsible for the electric charge of atoms. And force just being the physics concept of either a pushing and pulling motion between objects.
The actual law is stated as an equation: F = (K(Q1)(Q2))/r^(2), where F is force, K is Coulomb’s constant equal to 8.988×10^(9), Q1 is the magnitude of one charged object, Q2 is the magnitude of the other charged object, and r is distance between the two charged objects. In a physics class we would be concerned with actually calculating numbers, but in a chemistry class we’re only concerned with it to show trends in the interactions between charged particles. The main points of this law for a chemistry perspective is that there is greater force between particles which have greater magnitudes of charge, and less force between larger particles.b(10 votes)
- Electric force is directly proportional to charge magnitude, and inversely proportional to the square of the distance between the charged particles.(3 votes)
- why is there not another table for different types of bonds and molecules and how different elements react with each other(1 vote)
- It's better to understand the underlying concepts of bonding than to memorize each different molecule and interaction. The number of molecules we can make is truly limitless. Chemists synthesize molecules for the first time on a daily basis.(15 votes)
- How do covalent bonds work?(4 votes)
- there are different kinds of bonds, but a covalent bond is one which involves the sharing of electrons. For example, when 2 hydrogen atoms covalently bond, they share their electrons, forming H2. Therfore, hydrogen (which is naturally found as H2 because the single electrons really want to bond with other electrons) has 2 protons, 2 electrons, and 0 neutrons. I hope this helped :)(6 votes)
- What is the subatomic level?(4 votes)
- how can one study and prepare to take ap level chemistry in high school(7 votes)