What is the hyphen notation for an atom with 82 protons, 125 neutrons and 82 electrons?
The Correct Answer and Explanation is :
The hyphen notation for an atom with 82 protons, 125 neutrons, and 82 electrons is Lead-207 (Pb-207).
Explanation:
The hyphen notation is a way of representing an isotope of an element. It is written as the element symbol, followed by a hyphen, and the mass number of the isotope. The mass number is the sum of protons and neutrons in the nucleus of an atom.
Step-by-step breakdown:
- Protons: The number of protons in an atom determines the element. In this case, the atom has 82 protons, which corresponds to lead (Pb) on the periodic table. The atomic number of lead is 82, meaning that all atoms with 82 protons are lead atoms.
- Neutrons: The number of neutrons is not fixed for an element; different isotopes of the same element can have different numbers of neutrons. This particular atom has 125 neutrons.
- Mass Number: The mass number is the total of protons and neutrons. For this atom, the mass number is calculated as: [
\text{Mass number} = \text{Protons} + \text{Neutrons} = 82 + 125 = 207
] So, the mass number is 207. - Electrons: Since the atom is neutral (it has an equal number of protons and electrons), the number of electrons is also 82. The number of electrons is not needed for the hyphen notation, as the notation focuses on the atomic composition (protons and neutrons).
Conclusion:
The atom is a lead isotope with 82 protons and 125 neutrons, and its hyphen notation is Pb-207, where “Pb” is the symbol for lead and “207” is the mass number. This isotope is known as Lead-207, and it is stable and naturally occurring in trace amounts in the Earth’s crust.