# Contains 28 protons and 30 neutrons

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Write complete symbols, including mass number and atomic number,
for atoms with the following characteristics.

## General guidance

Concepts and reason
The mass number (A) of an atom is calculated by adding the number of protons and neutrons present in the atom. While writing the symbol of an atom, the atomic number should be written as sub-script and the mass number should be written as a superscript.
Fundamentals

Protons and neutrons are present in the nucleus and electrons revolve round the nucleus. The mass of an electron is negligible when compared to the mass of a proton neutron. Hence, mass number is calculated by adding the number of protons and neutrons. The atomic number (Z) of an element is equal to the number of protons present in the nucleus.

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As the atom is neutral, the number of protons is equal to the number of electrons.

## Step-by-step

### Step 1 of 5

The atomic number of the atom is 28.

Calculate the mass number of the atom as follows:

Therefore, the symbol of the atom is.

Therefore, the symbol of the atom is.

The number of protons in the atom is 28. The number of protons is equal to the atomic number. From the periodic table, it is evident that the element which has atomic number 28 is nickel (Ni).

### Step 2 of 5

The atomic number of the atom is 22.

Calculate the mass number of the atom as follows:

Therefore, the symbol of the atom is.

Therefore, the symbol of the atom is .

The number of protons in the atom is 22. The number of protons is equal to the atomic number. From the periodic table, it is evident that the element which has atomic number 22 is titanium (Ti).

### Step 3 of 5

The atomic number of the atom is 15. Hence, the number of protons in the atoms is 15.

Calculate the mass number of the atom as follows:

Therefore, the symbol of the atom is .

Therefore, the symbol of the atom is .

The number of electrons in the atom is 15. Since, the atoms is neutral, the number protons and number of electrons are equal. The number of protons is equal to the atomic number. Hence, the atomic number is 15. From the periodic table, it is evident that the element which has atomic number 15 is phosphorous (P).

### Step 4 of 5

The atomic number of oxygen atom is 8. Hence, the number of protons in oxygen is 8.

Calculate the mass number of the atom as follows:

Therefore, the symbol of the atom is.

Therefore, the symbol of the atom is .

The atomic number of oxygen is 8. Hence, the number of protons and the number of electrons in oxygen are equal to 8.

### Step 5 of 5

The mass number of chromium is 54. The atomic number of chromium is 24.

Therefore, the symbol of the atom is .

Therefore, the symbol of the atom is .