Identifying Bromine Isotopes Using The Periodic Table
In the fascinating world of chemistry, understanding the concept of isotopes is crucial. Isotopes are variations of a chemical element which share the same number of protons, and thus the same atomic number (Z), but have different numbers of neutrons, leading to different mass numbers (A). The mass number is the total number of protons and neutrons in an atom's nucleus. The identity of an element is defined solely by its number of protons, meaning isotopes of the same element will exhibit virtually identical chemical properties. However, their physical properties, such as mass and nuclear stability, can vary significantly.
The periodic table is our go-to guide for all things elements, including bromine (Br). Bromine, represented by the symbol 'Br', has an atomic number (Z) of 35. This means every bromine atom has 35 protons in its nucleus. The most common isotope of bromine has a mass number (A) of approximately 80, suggesting it also has about 45 neutrons (since A = number of protons + number of neutrons). However, isotopes can deviate from this norm, possessing different neutron counts while still retaining the 35 protons that define them as bromine.
To determine if a given atom is an isotope of bromine, we need to focus on one key factor: the number of protons. If an atom has 35 protons, it's bromine, regardless of its neutron count. This is where the given options come into play. We'll analyze each to see if it fits the bill for being a bromine isotope. The periodic table, with its clear listing of atomic numbers, becomes our indispensable tool in this quest, allowing us to quickly verify the proton count and, consequently, the element's identity. Remember, isotopes are like family members – they share a common last name (the element) but have slightly different characteristics (neutron count and mass).
Let's dive into the specifics of identifying bromine isotopes based on the provided data. To reiterate, the defining characteristic of an isotope is that it has the same number of protons (atomic number, Z) as the element in question but a different number of neutrons, leading to a different mass number (A). Bromine (Br), as we know from the periodic table, has an atomic number of 35. Therefore, any isotope of bromine must also have 35 protons. This is our golden rule for this exercise. We'll evaluate each option against this rule, using the given information about atomic number (Z), mass number (A), and neutron number (N).
Option 1: Z=79, A=196
In this scenario, the atom has an atomic number (Z) of 79. This immediately tells us that this is not an isotope of bromine. Remember, the atomic number defines the element. An element with 79 protons is gold (Au), not bromine. The mass number (A) of 196 is irrelevant in this determination; the proton number is the only thing that matters when identifying the element. So, we can confidently exclude this option as a bromine isotope. The periodic table clearly shows that elements are distinguished by their unique atomic numbers, and 79 simply doesn't align with bromine's 35.
Option 2: Z=35, A=79
This option presents an atom with an atomic number (Z) of 35. Bingo! This matches the atomic number of bromine. Therefore, this atom is an isotope of bromine. The mass number (A) is 79, which means this isotope has 35 protons and 44 neutrons (A - Z = 79 - 35 = 44). This is a perfectly valid isotope of bromine, just with a slightly different mass than the most common isotope. The key here is the 35 protons, which unequivocally identifies it as bromine. The periodic table confirms that any atom with 35 protons is, by definition, bromine.
Option 3: A=79, N=44
This option provides the mass number (A) as 79 and the number of neutrons (N) as 44. To determine if this is a bromine isotope, we need to calculate the atomic number (Z), which represents the number of protons. We know that A = Z + N, so we can rearrange this to find Z: Z = A - N. Plugging in the given values, we get Z = 79 - 44 = 35. Voila! The atomic number is 35, matching bromine. This means this atom is an isotope of bromine. It has 35 protons and 44 neutrons, resulting in a mass number of 79. Again, the proton number is the crucial factor, and it aligns perfectly with bromine's identity on the periodic table.
Option 4: Z=44, N=44
Here, the atom has an atomic number (Z) of 44. This is not bromine. An element with 44 protons is ruthenium (Ru), a completely different element located elsewhere on the periodic table. The number of neutrons (N) is irrelevant in this case; the differing proton count immediately disqualifies it as a bromine isotope. So, this option is not a bromine isotope. The periodic table serves as our definitive guide, and it leaves no room for doubt: 44 protons equals ruthenium, not bromine.
In summary, to determine if an atom is an isotope of bromine, the most important piece of information is its atomic number (Z). Bromine has an atomic number of 35, so any atom with 35 protons is a bromine isotope, regardless of its neutron count or mass number. By carefully examining the provided options and applying this principle, we can confidently identify which atoms qualify as bromine isotopes. The periodic table is our steadfast reference in this endeavor, providing the essential atomic numbers that define each element.
In the given set of options, two qualify as isotopes of bromine:
- Z=35, A=79
- A=79, N=44
These atoms share the defining characteristic of bromine: 35 protons. Their differing neutron counts give them slightly different masses, making them isotopes of the same element. This exercise highlights the fundamental concept of isotopes and their relationship to atomic structure, a cornerstone of chemistry.
