Proton Examples in Chemistry

Start with the recap, study the fully worked examples, then use the practice problems to check your understanding of Proton.

This page combines explanation, solved examples, and follow-up practice so you can move from recognition to confident problem-solving in Chemistry.

Concept Recap

A positively charged subatomic particle found in the nucleus of every atom, with a charge of +1+1 and a mass of approximately 1 atomic mass unit (amu).

The identity badge of an atom—how many protons determines what element it is.

Read the full concept explanation →

How to Use These Examples

  • Read the first worked example with the solution open so the structure is clear.
  • Try the practice problems before revealing each solution.
  • Use the related concepts and background knowledge badges if you feel stuck.

What to Focus On

Core idea: Proton starts by naming the element, charge, and relevant protons, neutrons, or electrons.

Common stuck point: Students often know a formula related to proton but skip the recognition step: Am I using particle counts, nuclear charge, mass number, electron arrangement, or isotope notation to describe an atom or ion? That leads to a correct-looking substitution attached to the wrong chemical model.

Sense of Study hint: Ask: Am I using particle counts, nuclear charge, mass number, electron arrangement, or isotope notation to describe an atom or ion?

Worked Examples

Example 1

easy
A sulfur atom has 16 protons. What is its atomic number, and how does the number of protons relate to its identity as sulfur?

Answer

Z=16Z = 16

First step

1
Recall that the atomic number ZZ is defined as the number of protons in the nucleus.

Full solution

  1. 2
    Read the atomic number from the periodic table: Z=16Z = 16, so this atom has 16 protons.
  2. 3
    Every atom with exactly 16 protons is sulfur (S), regardless of how many neutrons or electrons it has.
Protons define the identity of an element. The atomic number ZZ is simply the proton count and is the most fundamental property of an element.

Example 2

medium
The mass of a single proton is approximately 1.673×10−241.673 \times 10^{-24} g. How many protons would it take to have a combined mass of 11 g?

Example 3

hard
If a uranium atom (Z = 92) undergoes alpha decay, how many protons does the daughter nucleus have?

Practice Problems

Try these problems on your own first, then open the solution to compare your method.

Example 1

easy
How many protons are in an atom of potassium (K, atomic number 19)?

Example 2

medium
Why doesn't sodium turn into magnesium during an ordinary chemical reaction, even if electrons are lost or gained?

Example 3

easy
What is the electric charge of a single proton?

Example 4

easy
In which part of the atom are protons found?

Example 5

easy
Which subatomic particle's count determines the identity of an element?

Example 6

easy
A neutral carbon atom has 6 protons. How many protons does a carbon ion (C4+\text{C}^{4+}) have?

Example 7

easy
How does the mass of a proton compare to the mass of an electron?

Example 8

easy
How many protons does an atom with atomic number Z=8Z = 8 have?

Example 9

easy
Can protons be gained or lost during an ordinary chemical reaction?

Example 10

easy
In a neutral atom, how does the number of protons compare to the number of electrons?

Example 11

medium
An atom has a mass number of 19 and contains 10 neutrons. How many protons does it have, and what element is it?

Example 12

medium
Atom 1 has 7 protons; atom 2 has 8 protons. Are they the same element? Explain in one line.

Example 13

medium
A Mg2+\text{Mg}^{2+} ion has 10 electrons. How many protons does magnesium have?

Example 14

medium
Why do all isotopes of chlorine behave the same way chemically even though they differ in mass?

Example 15

medium
An atom has 15 protons. Predict its position role: is it a metal-region small ZZ or specific element, and name it.

Example 16

medium
Two atoms each have 6 protons. One has 6 neutrons, the other 8. What stays the same, and what differs?

Example 17

medium
A nucleus has 2 protons. What overall charge does the nucleus carry, and what element is it?

Example 18

medium
An atom has 1 proton and 2 neutrons (a hydrogen isotope). How many protons does it have, and what element is it?

Example 19

medium
A neutral atom has 20 protons. How many electrons does it have, and name the element?

Example 20

challenge
Element X has atomic number 26. An X atom loses 3 electrons. State its proton count, the ion charge, and the element name.

Example 21

challenge
A neutral atom of element Y has 11 protons. Compare Y to an atom with 11 protons and 1 extra neutron in terms of element, charge, and chemistry.

Example 22

challenge
Why does adding one proton to a nucleus change the element, but adding one neutron does not?

Example 23

easy
Helium (He, atomic number 2). How many protons does a He atom have?

Example 24

medium
An ion has 17 protons and 18 electrons. What is its net charge?

Example 25

medium
An ion has 12 protons and 10 electrons. What is its symbol and charge?

Example 26

medium
An atom of element X has 15 protons, 16 neutrons, and 15 electrons. What is X?

Example 27

medium
How many protons in S2−\text{S}^{2-}?

Example 28

medium
Compute the number of protons in Al3+\text{Al}^{3+} (Z = 13).

Example 29

medium
An isotope 31P{}^{31}\text{P} has 16 neutrons. How many protons does it have?

Example 30

medium
An isotope has mass number 56 and 30 neutrons. Identify the element.

Example 31

hard
A nucleus has mass number 40 and atomic number 20. Identify the element and give its proton count.

Example 32

medium
Carbon-14 undergoes beta decay. What element does it become?

Example 33

medium
A monatomic ion has 26 protons and 23 electrons. Write its symbol.

Example 34

medium
If element X has 24 protons, in what group of the periodic table does it sit?
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Related Concepts

AtomAtomic NumberNeutron

Background Knowledge

These ideas may be useful before you work through the harder examples.

atom