[mission]

I am an adult studying high school chemistry on my own. I'm at lost at how to use the atomic table.

Here's what I learn so far, the example is on Carbon:

IV      Number of electrons in the outer shell
6   Atomic Number   Equals to the number of its protons
C   Atomic Symbol   
12   Atomic Mass   Equals the number of protons plus the number of neutrons


Proton = 6 because Atomic number is 6
Electron = 6 because IV=4 on the outer shell + 2 in the inner shell
Neutron = 6 because the number 12 minus 6 protons from atomic number

So far so good.

Now I'm stumped with the example below for Potassium:

The answer has this numbers and I don't know how to get number of electrons:

Protons = 19   because from Atomic Number
Electrons = 19   how do you get 19?
Neutrons = 20 (39-19)  because Atomic Mass - Atomic Number

What is "IA"? How many electrons on the outer shell for potasium? There is 2 electrons on the inner shell, so if I minus (19-2=17), "IA" is 17? What is really the "IA"? How do you get the number of electrons in the case of potassium?

[Enthalpy]

Hi mission!

In a lone neutral atom of potassium (which exists in potassium vapour), the 19 protons attract electrons up to make an atom, neutral with 19 electrons.

K has several isotopes corresponding to varied numbers of neutrons, hence the average mass of 39.0983.

Ia is roman 1 for the first column, because K has 1 electron on its outer shell (hence called an "alkaline" element).

The shell filling is:
2+8+8+1, which can be detailed further as
1s²2s²2p⁶3s²3p⁶4s
where 1s² are 2 electrons as the 1s orbital (He stops there),
2s²2p⁶ are 2+6=8 electrons on 2s and 2p orbitals (Ne stops there),
3s²3p⁶ are 2+6=8 electrons on 3s and 3p orbitals (Ar stops there),
and 4s is the lone electron that makes K very reactive.

₁₉K is the heaviest element but one where the filling of orbitals follows a simple sequence. With ₂₁Sc begins a first set of transition elements, where 3d and 4s fill concurrently, their electron distribution changing with the chemical bonds.

[billnotgatez]

@mission

I am an adult studying high school chemistry on my own. I'm at lost at how to use the atomic table.

I wonder which text book you are using in addition to the Internet searches.
Also I wish you the best.

[yabbadabbadoodoodoo]

The number of electrons always equals the number of protons in an atom, so no calculations required, its right there in the periodic table!

[mission]

Hi mission!

In a lone neutral atom of potassium (which exists in potassium vapour), the 19 protons attract electrons up to make an atom, neutral with 19 electrons.

K has several isotopes corresponding to varied numbers of neutrons, hence the average mass of 39.0983.

Ia is roman 1 for the first column, because K has 1 electron on its outer shell (hence called an "alkaline" element).

The shell filling is:
2+8+8+1, which can be detailed further as
1s²2s²2p⁶3s²3p⁶4s
where 1s² are 2 electrons as the 1s orbital (He stops there),
2s²2p⁶ are 2+6=8 electrons on 2s and 2p orbitals (Ne stops there),
3s²3p⁶ are 2+6=8 electrons on 3s and 3p orbitals (Ar stops there),
and 4s is the lone electron that makes K very reactive.

₁₉K is the heaviest element but one where the filling of orbitals follows a simple sequence. With ₂₁Sc begins a first set of transition elements, where 3d and 4s fill concurrently, their electron distribution changing with the chemical bonds.

I wouldn't say I understand all that at this time. That looks complicated. I didn't expect them to use such a complicated atom (K) in an introduction to the periodic table. The carbon example was simple, I thought it wasn't a good example because the atomic mass is 12 and atomic number is 6, 6 + 6 = 12 sounds simple. But what about atoms with atomic mass, lets say 13. If the atomic number is 6, can I say the neutron is 7 because 13-6=7?? Ok, this can be wrong, the way to calculate is to look at the answer you have just given. I'm going to leave this for now and move on to the next section, until they cover the periodic table again. I will keep that in mind when I will revisit that again. Thank you.

[mission]

@mission

I am an adult studying high school chemistry on my own. I'm at lost at how to use the atomic table.

I wonder which text book you are using in addition to the Internet searches.
Also I wish you the best.

There is no textbook. Just handouts and a workbook. Actually, I'm doing biology as well, that question actually came from my biology course (page 3, link below). For Chemistry, I'm working on unit conversions and significant figures, no periodic table yet.

https://drive.google.com/file/d/0B3WOn7bUIH4uNER1NG5xNU15eVk/view?usp=sharing

[mission]

The number of electrons always equals the number of protons in an atom, so no calculations required, its right there in the periodic table!

Let me see.

Atomic Number = 19, so proton = 19
# of electron = # of proton, so electron = 19

Atomic Mass = number of protons plus the number of neutrons
39 = 19 + neutrons
39 - 19 = neutrons
neutrons = 20

Sound simple, so far.

You said "The number of electrons always equals the number of protons in an atom", I thought I read somewhere "When an atom is electrically neutral, the number of protons equal number of electrons", is your statement still true or do I need to find out if the atom is electrically neutral?

[Borek]

You said "The number of electrons always equals the number of protons in an atom", I thought I read somewhere "When an atom is electrically neutral, the number of protons equal number of electrons", is your statement still true or do I need to find out if the atom is electrically neutral?

Atoms are neutral. When they become charged, they are called "ions".

I wouldn't say I understand all that at this time. That looks complicated. I didn't expect them to use such a complicated atom (K) in an introduction to the periodic table. The carbon example was simple, I thought it wasn't a good example because the atomic mass is 12 and atomic number is 6, 6 + 6 = 12 sounds simple. But what about atoms with atomic mass, lets say 13. If the atomic number is 6, can I say the neutron is 7 because 13-6=7?? Ok, this can be wrong, the way to calculate is to look at the answer you have just given. I'm going to leave this for now and move on to the next section, until they cover the periodic table again. I will keep that in mind when I will revisit that again. Thank you.

Actually potassium is not that difficult. What if you deal with chlorine, with atomic mass of 35.5? You are right about one thing - this is more complicated. But you have to start somewhere, don't worry about these things for now.

[Enthalpy]

The number of neutrons per atom varies within an element. It defines instead the isotope of the element. A few elements have only one natural isotope, all (or almost all?) elements have man-made unstable isotopes, and most elements have a handful of isotopes.

So if counting neutrons, one has to decide for which isotope; the element doesn't suffice.
³⁹₁₉K has 39 nucleons, of which 19 are protons hence 20 are neutrons.
But the (natural and radioactive) ⁴⁰₁₉K has 21 neutrons, and
the natural and stable ⁴¹₁₉K has 22 neutrons.
Then you have radioisotopes, of which ³⁷K to ⁴⁹K are known.
http://www.webelements.com/potassium/isotopes.html

[Kimisti]

you should definitely get a high school textbook for chemistry,everything is explained more detailed,because its hard to understand chemistry just from overview coverings of chapters

[Cobalt]

In school, I learned this thing. It's called APE MAN.

It stands for:


A.P.E.

Atomic Number = Protons = Electrons

So, whatever your atomic number is, that is the amount of protons and electrons you will have.

As for neutrons, they are different because they have no charge.

M.A.N.

Mass - Atomic Number = Neutrons


So when finding the protons, neutrons, and electrons, just remember APE MAN.


You were looking for the electrons, right? It's the same amount of the protons.


Source: 7th Grade

[mission]

I thank everyone here for the help and input.

The webelements.com looks like a great site, I guess I will be using it a lot later.

For those curious, this is what I will be doing for this self study chemistry course.

Chemistry 11
Topics of Study
Unit 1: Introduction to Chemistry
Unit 2: Properties of Substances
Unit 3: Introduction to Inorganic Nomenclature
Unit 4: The Mole Concept
Unit 5: Chemical Reactions
Unit 6: Atomic Structure
Unit 7: The Periodic Table
Unit 8: Introduction to Chemical Bonding
Unit 9: Solution Chemistry
Unit 10: Organic Chemistry

[mission]

In school, I learned this thing. It's called APE MAN.

It stands for:


A.P.E.

Atomic Number = Protons = Electrons

So, whatever your atomic number is, that is the amount of protons and electrons you will have.

As for neutrons, they are different because they have no charge.

M.A.N.

Mass - Atomic Number = Neutrons


So when finding the protons, neutrons, and electrons, just remember APE MAN.


You were looking for the electrons, right? It's the same amount of the protons.


Source: 7th Grade

That APE MAN is awesome, certainly what I need for this course. Thank you.