Question 1

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?

Accepted Answer

They are individual atoms of a new element. Compounds are two or more atoms chemically bonded into a molecule.

Question 2

Does every element have an isotope(s)

Accepted Answer

All atoms are isotopes. All atoms are elements. Therefore all elements have isotopes.

Question 3

Hello 
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?

Accepted Answer

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.

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.

Question 4

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*

Accepted Answer

Electric force is directly proportional to charge magnitude, and inversely proportional to the square of the distance between the charged particles.

Question 5

What is an easy way to memorize the Periodic table of elements?

Accepted Answer

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... :)

Question 6

How do covalent bonds work?

Accepted Answer

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 :)

Question 7

What is the subatomic level?

Accepted Answer

The level below the size of atoms. Usually used to refer to protons, neutrons and electrons.

Question 8

why is there not another table for different types of bonds and molecules and how different elements react with each other

Accepted Answer

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.

Question 9

can you please tell me what makes acids acid and bases base. what is special in them

Accepted Answer

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.

Course: AP®︎/College Chemistry > Unit 1

Preparing to study chemistry

Welcome to the world of chemistry!

Math

General skills

Science-specific skills

Physics and biology

Want to join the conversation?