1. QUESTION:
The symbol 13C or C-13 represents an atom with… A. 13 protons, B. 13 electrons, C. 13 neutrons D. 13 nucleons
The atomic number of a carbon atom and find it to be 6. Therefore any carbon atom has 6 protons.
An atom is neutral. The number of protons and electrons are the same. Therefore, any carbon atom has 6 electrons.
The number written as a superscript is the “mass number” = total number of protons AND neutrons (6 protons, 7 neutrons)
Collectively, protons and neutrons are called nucleons, since they are found in the nucleus.
SCRIPT:
The symbol C with 13 written as a superscript before it,
HIGHLIGHT 13C or with dash 13 written after it,
HIGHLIGHT C-13
represents an atom with… A. 13 protons B. 13 electrons C. 13 neutrons D. 13 nucleons
PAUSE
CLICK.
The symbol C stands for carbon, and we read this symbol shown her as “carbon thirteen”
The number of protons in an atom is equal to its atomic number. The atomic number of carbon is 6.
Therefore Choice A is wrong. A carbon atom cannot have 13 protons. Any carbon atom has six protons.
CROSS OUT A
CLICK Any atom is neutral. This means that it has equal numbers of protons and electrons. Protons and electrons
Have equal but opposite charges. Therefore, any carbon atom also has six electrons, and choice B is wrong.
CROSS OUT B
SO what exactly does the number 13 shown here? CLICK It’s called the mass number.
HIGHLIGHT mass number
It is the total number of protons AND neutrons.
This means that the symbol represents an atom with 7 neutrons.
Since we have already established that this atom has 6 protons equals 13.
Therefore choice C is wrong. This atom has 7 neutrons, not 13.
Therefore, choice D must be the correct answer.
Indeed it is. Since protons and neutrons are found in the nucleus, they are collectively referred to as nucleons.
There are 13 nucleons in carbon thirteen. Six of those nucleons are protons, the other 7 are neutrons.
CONTINUED ON NEXT SLIDE

2. If you don’t know how to find the atomic number, here’s how you can find it from a periodic table.
Each element in the periodic table typically come with at least two numbers. The smaller number, … the whole number… is the atomic number.
As you can see here, the atomic number of carbon is 6.
HIGHLIGHT 6
CLICK
CONTINUED ON NEXT SLIDE

3. 1 2 3 4 5 6 57 72 89
104
Occasionally, you get a periodic table that only has symbols for the elements, but no numbers. You can still figure out the the atomic number of any element
Because they are arranged in order of increasing atomic number from left to right, top to bottom.
So, the atomic numbers are
CLICK one for hydrogen
CLICK two for helium
CLICK three for lithium
CLICK
Four for beryllium
Five for boron
Six for carbon
And so on…
Note that there is a break in the numbering once you get to Lanthanum, which is number 57
Elements with atomic numbers 58 through 71 are typically shown below.
CLICK These elements are called the Lanthanides.
The numbering resumes with hafnium, number 72.
On some periodic tables, Lanthanum is shown with the lanthanides, and lutetium, number 71 is shown in its place.
There’s another break once you get to Actinium,
CLICK Actinium has an atomic number of 89.
Elements 90 through through 103 are typically shown below the lanthanides.
These elements are called the actinides.
Then the numbering resumes with Rutherfordium.
On some periodic tables, actinium is shown below with the actinides, and lawrencium, number 103 is shown in its place.
CONTINUED ON NEXT SLIDE
58 through 71
90 through 103

4. Here’s a more complete way of representing a carbon-thirteen atom.
In addition to the mass number
CALLOUT “mass number” pointing to 13
The atomic number is written as a subscript to the left of the symbol
CALLOUT “atomic number” pointing to 6
In a way, this is redundant since we know that for any atom to be called carbon, it must have 6 protons.
PAUSE CLICK END RECORDING

5. Video ID: © 2008, Project VALUE (Video Assessment Library for Undergraduate Education), Department of Physical Sciences Nicholls State University Author: Glenn V. Lo Narrator: Funded by Louisiana Board of Regents Contract No. LA-DL-SELECT-13-07/08