Question

What is mass number of an atom with 19 electrons and 20 neutrons?
e -=
p +=
n 0 =
atomic mass=

Answers

GPT-4o mini
To determine the mass number of an atom, you can use the formula:

\[
\text{Mass Number (A)} = \text{Number of Protons (Z)} + \text{Number of Neutrons (N)}
\]

1. **Electrons:** The number of electrons in a neutral atom is equal to the number of protons. Since there are 19 electrons, the atom has 19 protons.

\[
\text{Number of Protons (p)} = 19
\]

2. **Neutrons:** According to the information given, the atom has 20 neutrons.

\[
\text{Number of Neutrons (n)} = 20
\]

3. **Mass Number:** Now, we can calculate the mass number:

\[
\text{Mass Number (A)} = \text{Number of Protons (p)} + \text{Number of Neutrons (n)} = 19 + 20 = 39
\]

So, we can summarize the information as follows:

- **e (electrons)** = 19
- **p (protons)** = 19
- **n (neutrons)** = 20
- **atomic mass (mass number)** = 39

The mass number of the atom is **39**.

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