Problem 67 - Chemistry Matter and Change

Question

Carbon A carbon atom has a mass number of 12 and an atomic number of 6. How many neutrons does it have?

Step-by-Step Solution

Answer

The carbon atom has 6 neutrons, as calculated by the formula: Number of Neutrons = Mass Number - Atomic Number, which in this case is \(6 = 12-6\).

Step 1: Identify the mass number and atomic number of Carbon.

The mass number of Carbon is given as 12, and the atomic number is given as 6.

Step 2: Use the Formula to Determine the Number of Neutrons

We'll use the formula mentioned above: Number of Neutrons = Mass Number - Atomic Number Plug the values in the formula: Number of Neutrons = 12 - 6

Step 3: Calculate the Number of Neutrons

Now, subtract the atomic number from the mass number to find the number of neutrons: Number of Neutrons = 12 - 6 = 6 So, the carbon atom has 6 neutrons.

Key Concepts

Understanding Mass Number

The mass number is a crucial part of understanding the atomic structure of an element. It is defined as the total number of protons and neutrons present in the nucleus of an atom. Typically represented by the letter 'A', this number gives us an idea of the relative mass of the atom.
Since protons and neutrons make up most of the atomic mass, the mass number can be thought of as the total count of these subatomic particles. Electrons, due to their relatively negligible mass, are not considered when calculating the mass number.

• Example: For a carbon atom, the mass number is 12.

This means there are a combined total of 12 protons and neutrons in carbon's nucleus.

Understanding Atomic Number

The atomic number is another fundamental concept in atomic structure. It is symbolized by the letter 'Z' and represents the number of protons found in the nucleus of an atom. This number is also equal to the number of electrons in a neutral atom, as atoms maintain charge balance.
Each element has its own unique atomic number, which helps classify the element and determine its position in the periodic table.

• Example: For a carbon atom, the atomic number is 6.

This tells us that a carbon atom has 6 protons in its nucleus, defining its chemical nature.

Calculating Neutrons in an Atom

Neutrons play a crucial role in the nucleus, providing stability to the atom. Calculating how many neutrons are present involves understanding and utilizing both the mass number and atomic number.
To find the number of neutrons in an atom, use the formula:
\[ \text{Number of Neutrons} = \text{Mass Number} - \text{Atomic Number} \]
This simple subtraction will give you the number of neutrons in the atom.

• Example: For carbon, with a mass number of 12 and an atomic number of 6, the number of neutrons is:

Subtract the atomic number (6 protons) from the mass number (12 total nucleons):
\[ \text{Number of Neutrons} = 12 - 6 = 6 \]
The carbon atom, therefore, contains 6 neutrons.