# Given the mass number and atomic number, how do you determine the number of neutrons?

###### Question:

## Answers

a. mass number from atomic number

B. Atomic number from mass number

Explanation:

The general form for an atomic symbol of an element X is

[tex]_{Z}^{A}\text{X}[/tex]

where

Z = the atomic number = the number of protons = p

A = the mass number =the number of protons plus neutrons =p + n

So, to get the number of neutrons, you take

A – Z = (p + n) – p = n

In words,

Mass number – atomic number = number of protons

im pretty sure Lithium's mass is 6.941grams for 1

Option B is the correct answer, because the number of neutron is equal to the difference between the mass number and atomic number.

Further explain:

Before going about the calculation of the number of neutron in an atom, firstly we will know something about an atom.

An atom is a fundamental unit of matter. It is composed of nucleus and electrons orbiting around the nucleus.

The electrons in an atom are orbiting around the nucleus in the shells of different energies.

Maximum part of the mass of an atom is concentrated in its nucleus and it is composed of proton and neutron. They are also known as nucleons of an atom.

Proton and electron are the charge particles. Proton carries the positive charge while electron carries the negative charge of same amount, but neutron does not carry any type of charge so it is neutral.

The total number of electron is equal to the total number of proton is an atom.

That’s why atoms are neutral in nature.

Atomic number: The total number of electron or total number of proton in an atom is known as the atomic number.

[tex]{A_n}=P[/tex]

Here, [tex]{A_n}[/tex] is the atomic number and [tex]P[/tex] is the number of proton.

Atomic mass: The sum of number of proton and neutron in an atom is known as atomic mass or mass number.

So, atomic mass can be calculated as,

[tex]\boxed{M = P + N}[/tex]

Here, [tex]M[/tex] is the atomic mass or mass number and [tex]N[/tex] is the number of neutron .

So, number of neutron can be calculated as,

[tex]\boxed{N = M - P}[/tex]

So, number of neutron is equal to the difference between the mass number and number of proton or atomic number.

Learn more:

1. Water is a compound:

2. Acceleration of the box against the friction:

3. Example of energy

Answer detail:

Grade: High school

Subject: Chemistry

Chapter: Atom

Keyword:

Number of neutron, mass number, proton, electron, atomic number, atom, nucleus, difference, atomic mass, subtraction, orbit, neutral.

To find the number of neutrons in an atom, subtract B. Atomic number from Mass number

To find the number of neutrons in an atom, what we must do is to follow the following steps:

1) Find the element in the periodic table.

2) Find the atomic number of the element. The atomic number is the number of protons of a single atom of that element.

3) Find the atomic weight of the element.

4) Finally, we look for the number of neutrons. For this, we follow the following relationship:

Atomic weight - number of protons = number of neutrons.

To find the number of neutrons in an atom, you would subtract:

B.) atomic number from mass number

Atomic number is same number as the protons...

Neutrons = Mass number - Atomic number ( protons)

Electrons are same number as protons unless the element has a charge..

If it has a charge of +2 it means that the element has 2 less electrons than the neutral atom. If it has a charge of -2 it means that the element has 2 more electrons than what it is supposed to..

Attached to this answer is the format of Isotope Notation that you can use for future reference. (Please open)

There are 8 Protons. The Atomic Number is the same number of an element's proton.

If you can see in the format, the mass number is calculated by adding the atomic number/protons and neutrons.

Mass number = 8 + 11

Mass number = 19

The image of the final answer is attached as well.

[tex]Write the symbolic notation of an isotope of an element having 8 protons, 8 electrons, and 11 neutro[/tex]

[tex]Write the symbolic notation of an isotope of an element having 8 protons, 8 electrons, and 11 neutro[/tex]

Describe the changes in the atomic model over time.

The existence of atoms began to be accepted around 1910 when many theories called upon the fact that atoms most exist (for example the work of Boltzmann trying to explain entropy, died 1906).

At that time atoms were seen as tiny small ball like objects, all matter was composed of. the models have been advanced ever since. Key names that are worth looking up are J. J. Thomson, Rutherford, Bohr and de Broglie.

Explain how different observations and experiments led to changes in the atomic model.

Many of the models that the men above proposed were created upon what they saw from their experiments. An example is that Niels Bohr wanted to explain the spectral lines in hydrogen, introducing the energy shells are quantized.

de Broglie saw that we could calculate wavelengths for particles with a certain velocity, introducing the particle wave duality.

Rutherford suggested that electrons are orbiting the nucleus like planets.

Thomson that there was a "electronsness" surrounding a positive core.

They can all be explain more deeply, but this is just introductory.

The number of n protons can be easily determined by its atomic number. With the atomic number and mass number (rounded If not already), then with basic subtraction we can calculate the number of neutrons...

Hope that helped!