Question

An element used to sanitize water supplies has two naturally occurring isotopes with mass numbers of 35 and \(37,\) and 17 electrons. Write the symbols for both isotopes, including their atomic numbers and mass numbers.

Short answer

The symbols are \( ^{35}_{17} \text{Cl} \) and \( ^{37}_{17} \text{Cl} \).

Step-by-step solution

Identify the Element

The element used to sanitize water supplies is chlorine. Chlorine has 17 electrons, implying it has an atomic number of 17.

Identify the Isotopes

Chlorine has two naturally occurring isotopes of mass numbers 35 and 37.

Write the Symbol for the First Isotope

The symbol for chlorine is Cl. For the isotope with mass number 35, the notation is \[ ^{35}_{17} \text{Cl} \] Here, 17 is the atomic number and 35 is the mass number.

Write the Symbol for the Second Isotope

Similarly, for the isotope with mass number 37, the notation is \[ ^{37}_{17} \text{Cl} \] Here, 17 is the atomic number and 37 is the mass number.

Key concepts

Atomic Number

The atomic number of an element is a fundamental concept in chemistry. It is the number of protons found in the nucleus of an atom. For any neutral atom, the atomic number is also equal to the number of electrons orbiting the nucleus. This number is crucial because it defines the identity of the element. For example, chlorine, which is used to sanitize water, has an atomic number of 17. This means every chlorine atom has 17 protons and, in its neutral state, also 17 electrons. The atomic number is typically represented by the letter "Z", and it determines an element's position on the periodic table. Understanding atomic numbers helps in predicting chemical properties and behaviors of elements.

Mass Number

The mass number of an isotope reflects the total number of protons and neutrons in an atom's nucleus. It is usually denoted by the letter "A". For instance, chlorine has two isotopes with mass numbers of 35 and 37. This means that while both isotopes have the same number of protons (which is 17, the atomic number), their number of neutrons differs. The isotope with a mass number of 35 has 18 neutrons, calculated by subtracting the atomic number (17) from the mass number (35). The isotope with a mass number of 37 has 20 neutrons. The mass number is crucial because it helps differentiate between isotopes of the same element, which contain the same number of protons but a different number of neutrons.

Chlorine Isotopes

Chlorine is an element that exists naturally as a mixture of isotopes. The two primary isotopes of chlorine have mass numbers 35 and 37. Isotopes are variants of a particular chemical element that have the same number of protons but a different number of neutrons. This results in different mass numbers for the isotopes.

The notation for these isotopes typically includes the mass number as a superscript and the atomic number as a subscript before the chemical symbol. For chlorine's isotopes, they are represented as:

• \( ^{35}_{17} \text{Cl} \)
• \( ^{37}_{17} \text{Cl} \)

These isotopes of chlorine play a significant role in chemical reactions and processes due to their specific properties. Despite their mass differences, they exhibit similar chemical behavior since chemical properties are largely determined by the number of protons and electrons.