Question

Give the symbol showing the atomic number and the mass number for the isotope that has: a. 9 protons and 10 neutrons (used in nuclear medicine). b. 26 protons and 30 neutrons (the most stable isotope of this element). c. 86 protons and 136 neutrons (the radioactive gas found in some homes).

Short answer

a. \(^{19}_{9}\text{F}\), b. \(^{56}_{26}\text{Fe}\), c. \(^{222}_{86}\text{Rn}\).

Step-by-step solution

Identify the Atomic Number

The atomic number of an element is equal to the number of protons in its nucleus. Therefore, for part (a), the atomic number is 9. For part (b), it is 26, and for part (c), it is 86.

Identify the Mass Number

The mass number of an isotope is the sum of the number of protons and neutrons in the nucleus. So, for part (a), the mass number is 9 + 10 = 19. For part (b), it is 26 + 30 = 56. For part (c), it is 86 + 136 = 222.

Determine the Element Symbols

Find the chemical symbol for each element using the atomic number: - Atomic number 9 corresponds to Fluorine (F). - Atomic number 26 corresponds to Iron (Fe). - Atomic number 86 corresponds to Radon (Rn).

Write the Symbol for Each Isotope

Use the format \[ ^{\text{Mass Number}}_{\text{Atomic Number}} \text{Symbol} \] to write the isotope symbols:- For Fluorine with mass number 19: \[ ^{19}_{9} \text{F} \]- For Iron with mass number 56: \[ ^{56}_{26} \text{Fe} \]- For Radon with mass number 222: \[ ^{222}_{86} \text{Rn} \]

Key concepts

Atomic Number

The atomic number is fundamental when identifying elements and understanding isotopes. It represents the number of protons found in the nucleus of an atom. Each element is defined by its atomic number, and it is unique to that element.

For instance, the atomic number 9 corresponds to Fluorine, meaning every Fluorine atom has 9 protons in its nucleus. Similarly, Iron has an atomic number of 26 and Radon is identified by its atomic number of 86.

Understanding the atomic number is crucial as it helps in arranging elements in the periodic table and also provides a basis for predicting the chemical properties of an element.

Mass Number

The mass number of an isotope is the total count of protons and neutrons in its nucleus. Unlike the atomic number, which is fixed, the mass number can vary depending on the number of neutrons. This variation gives rise to different isotopes of an element.

For example:

• Fluorine can have a mass number of 19 (9 protons + 10 neutrons).
• Iron may have a mass number of 56 (26 protons + 30 neutrons).
• Radon can be encountered with a mass number of 222 (86 protons + 136 neutrons).

The mass number is usually written as a superscript to the left of an element's symbol, providing a quick insight into the isotope's atomic structure.

Chemical Symbols

Chemical symbols are like unique identifiers for elements on the periodic table. They consist of one or two letters, where the first letter is always capitalized, and the second, if present, is lowercase. These symbols come from either the element's English name or its Latin name.

For the elements mentioned:

• Fluorine is represented by 'F'.
• Iron is depicted as 'Fe', derived from its Latin name Ferrum.
• Radon uses the symbol 'Rn'.

Chemical symbols, combined with atomic and mass numbers, help us write isotope notations accurately. This notation not only tells us the element but also informs us of the nucleus composition using a sleek and standardized method. For instance, the isotope notation for Fluorine with a mass number of 19 is written as \( ^{19}_{9} \text{F} \). The atomic number is at the bottom left and the mass number is at the top left, forming a complete picture of the isotope.