Question

Describe the two different notations used to specify isotopes and give an example of each.

Short answer

The two notations are hyphen and nuclear symbol notations. An example in hyphen notation is Carbon-13, while in nuclear symbol notation it is \( _{6}^{13}\text{C} \).

Step-by-step solution

Describing the hyphen notation for isotopes

The hyphen notation indicates an isotope by writing the element's name followed by a hyphen and then the mass number (total number of protons and neutrons in the nucleus).

Providing an example of hyphen notation

For instance, the notation for the isotope of carbon with 6 protons and 7 neutrons is Carbon-13, where 13 is the mass number (6 protons + 7 neutrons).

Describing the nuclear symbol notation for isotopes

The nuclear symbol notation shows the element's chemical symbol, the mass number as a superscript to the left, and the atomic number (number of protons) as a subscript to the left. This indicates both the identity of the element and the specific isotope.

Providing an example of nuclear symbol notation

The same isotope of carbon mentioned earlier is represented in nuclear symbol notation as \( _{6}^{13}\text{C} \) where 6 (the atomic number) is the subscript and 13 (the mass number) is the superscript to the left of the chemical symbol C.

Key concepts

Hyphen Notation

Hyphen notation is one of the simplest ways to identify isotopes. In this notation, an isotope is named by taking the element's name and appending its mass number with a hyphen. The mass number, which is the sum of protons and neutrons in the nucleus of the atom, is crucial in specifying the isotope.

For example, consider the isotope of hydrogen known as Deuterium. Deuterium has one proton (like all hydrogen atoms) and one neutron (which is not present in the most common hydrogen isotope). Using hyphen notation, Deuterium is written as Hydrogen-2, indicating that the total number of protons and neutrons is two.

Nuclear Symbol Notation

In contrast to hyphen notation, nuclear symbol notation provides more detailed information. This includes both the atomic number and the mass number of the isotope. The atomic number, located as a subscript, denotes the number of protons in the nucleus, which determines the chemical element. The mass number, shown as a superscript, indicates the total number of protons and neutrons.

Using the previously mentioned isotope, Deuterium, in nuclear symbol notation it would be represented as \( _{1}^{2}\text{H} \). Here, the subscript 1 signifies that hydrogen has one proton, and the superscript 2 indicates that the total number of protons and neutrons adds up to two.

Mass Number

The mass number is a fundamental concept in understanding isotopes as it relates to the weight of an atom. It's defined as the sum of the number of protons and neutrons in the nucleus of an atom. Since these particles account for almost all of an atom's mass, the mass number closely approximates the atomic weight. Different isotopes of an element have the same number of protons (and therefore the same atomic number) but differ in their number of neutrons, leading to differences in their mass numbers.

For instance, Carbon-12 and Carbon-14 are both isotopes of carbon, but Carbon-12 has 6 protons and 6 neutrons, whereas Carbon-14 has 6 protons and 8 neutrons. The mass numbers are 12 and 14, respectively, reflecting the different numbers of neutrons.

Atomic Number

The atomic number is perhaps the most crucial attribute of an element, as it defines the element's identity in the periodic table. This number is equal to the number of protons in the nucleus of an atom. Regardless of the isotope, the atomic number remains constant for all atoms of a given element because changing the number of protons results in a different element altogether.

For example, all carbon atoms contain 6 protons, so the atomic number for carbon is 6. This number can be found under the element's symbol on the periodic table and is crucial in writing the nuclear symbol notation for isotopes, as seen with the carbon isotope \( _{6}^{13}\text{C} \), where 6 represents carbon's atomic number.