How many protons, neutrons and electrons are in selenium
−
77?

Question

How many protons, neutrons and electrons are in selenium 
−
 77?

BlackTom AI · Accepted Answer

Selenium has atomic number 34, so it contains 34 protons.

1) Relevant knowledge points and concepts
- Atomic number (Z) equals the number of protons and identifies the element (for Se, Z = 34).
- Mass number (A) equals protons + neutrons; isotopes are denoted as element‑A (e.g., Se‑77 means A = 77).
- For a neutral atom, number of electrons = number of protons. If an ion is present, electrons differ by the ion charge.

2) Step‑by‑step reasoning
- Identify Z for selenium from the periodic table: Z = 34 → protons = 34.
- Identify A from the isotope notation: A = 77 for Se‑77.
- Use A = protons + neutrons to find neutrons: neutrons = A − protons.

3) Calculations with intermediate steps
- protons = 34 (from atomic number).
- neutrons = A − protons = 77 − 34.
- Compute 77 − 34 = 43.
- For a neutral Se atom: electrons = protons = 34.

4) Why the correct answer is correct
- The mass number 77 indicates the combined count of protons and neutrons; subtracting the known proton count (34) yields 43 neutrons. Because no charge is specified, the atom is neutral, so it has 34 electrons equal to its 34 protons.

5) Why other answers would be incorrect (brief)
- A common mistake is to report neutrons = 77 (confusing mass number with neutrons) or to swap numbers. Another error is changing electron count without an indicated ion charge. Any answer not giving neutrons = 43 or electrons = 34 contradicts A = Z + N or the neutrality condition.

6) Conclusion
Therefore, selenium‑77 has 34 protons, 43 neutrons, and 34 electrons, which matches the provided answer: 34, 43, 34.

How many protons, neutrons and electrons are in selenium − 77?单项选择题

类似问题

An atom of Beryllium isotope has in its nucleus

Which of the following best describes an Isotope?

When we describe different isotopes of the same element, such as Carbon-12, Carbon-13, and Carbon-14, what is the main difference between them?

Why do different isotopes of the same element have similar chemistry?

Which pair represents a set of isotopes?

The atomic mass of rhenium is 186.2 amu. It has two naturally occurring isotopes. Given that 37.1% of natural rhenium is rhenium–185, what is the other stable isotope?

Isotopes of an element differ in that they have the same number of [ Select ] neutrons protons but different numbers of [ Select ] neutrons protons .

Isotopes of an element differ in that they have the same number of protons but different numbers of neutrons .

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单