- 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
Preparing to study chemistry
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!
- Properties of exponents and properties of logarithms: Being comfortable with using logs and exponents will be helpful for acid and bases, kinetics, and equilibrium.
- 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!
- Dimensional analysis: My number two rule for learning chemistry is to always always check the units. Dimensional analysis is a helpful tool for making sure the units of different quantities make sense in any scientific calculation.
- 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?(187 votes)
- They are individual atoms of a new element. Compounds are two or more atoms chemically bonded into a molecule.(204 votes)
- Does every element have an isotope(s)(34 votes)
- All atoms are isotopes. All atoms are elements. Therefore all elements have isotopes.(98 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.(18 votes)
- What is an easy way to memorize the Periodic table of elements?(6 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... :)(9 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)
- The level below the size of atoms. Usually used to refer to protons, neutrons and electrons.(6 votes)
- Who gave Chemistry its name?(5 votes)
- Hi! It is said that Robert Boyle was the first modern chemist and gave Chemistry its name. He is commonly known as one of the founding fathers of Chemistry. The word 'chemistry' is said to have Greek origins.
Hope this helps!!:)(2 votes)
- How important are the properties of logarithms in chemistry? and how well should I know them?(1 vote)
- They can be helpful at times. The function p is defined as -log so pH is -log[H+]. You won't always need them but switching between log and base ten becomes important if you take classes like AP Chem.(3 votes)
- Why do we need Physics or Biology in study of Chemistry?(2 votes)
- One way of thinking about it is that since chemistry is the study of matter and its properties, we need a wide perspective. Matter can be diverse and come in many forms ranging from the basic to the complex. At its most basic level, matter is just particles in motion interacting with each other. This is what physics is, so knowing physics helps chemistry understand the fundamentals of matter. If we get more complicated, matter can assemble itself into living organisms. Which is what biology studies, so to understand more complicated forms of matter chemistry needs to know biology.
Another way of thinking about it is that chemistry acts as the bridge between physics and biology. As we expand our knowledge of chemistry in one direction, we inevitable begin to overlap with the study of physics. There’s a field of chemistry which studies specifically the overlap of physics and chemistry called physical chemistry. And if we expand our knowledge of chemistry in the other direction, we begin to overlap with the study of biology. The field of chemistry which studies the overlap of chemistry and biology is called biochemistry.
Hope that helps.(6 votes)