How To Calculate The Number Of Protons, Neutrons And Electrons In ...

Find a tutorHow it worksPricesResourcesFor schoolsBecome a tutor

+44 (0) 203 773 6024

Log inSign upAnswers>Chemistry>GCSE>ArticleHow to calculate the number of protons, neutrons and electrons in an atom of chlorine?

Protons have a +1 charge and electrons have a -1 charge. The overall charge on an atom is 0, therefore there must be an equal number of protons and electrons in an atom so that the charges cancel out. So in chlorine, we can see that the atomic number is 17. This means that each chlorine atom has 17 protons and therefore must also have 17 electrons.The nucleus of an atom contains protons and neutrons. The nucleus is the main contributor to the mass of the atom, meaning that the mass number can tell us the number of protons and neutrons in an atom. Each proton and neutron has a relative mass of 1 unit. Therefore we can subtract the number of protons from the atomic mass number in order to work out the number of neutrons. Chlorine has a mass number of 35, minus the 17 protons means that chlorine has 18 neutrons.

ATAnswered by Abbey T. • Chemistry tutor

47717 Views

See similar Chemistry GCSE tutors

Need help with Chemistry?

One-to-one online tuition can be a great way to brush up on your Chemistry knowledge.

Have a Free Meeting with one of our hand picked tutors from the UK's top universities

Find a tutor

Download MyTutor's free revision handbook?

This handbook will help you plan your study time, beat procrastination, memorise the info and get your notes in order.

8 study hacks, 3 revision templates, 6 revision techniques, 10 exam and self-care tips.

Download handbook

Free weekly group tutorials

Join MyTutor Squads for free (and fun) help with Maths, Coding & Study Skills.

Sign up

Related Chemistry GCSE answers

All answers ▸

In fractional distillation the shorter hydrocarbons have lower boiling points and distil off first. Why?

Answered by Hannah B.

Why can you separate crude oil using distillation?

Answered by Lydia W.

what are isotopes and why do they have the same properties?

Answered by Sito E.

How do you calculate an empirical formula

Answered by Tanisha S.

We're here to help

Contact us+44 (0) 203 773 6020

Company Information

CareersBlogSubject answersBecome a tutorSchoolsSafeguarding policyFAQsUsing the Online Lesson SpaceTestimonials & pressSitemapTerms & ConditionsPrivacy Policy

Popular Requests

Maths tutorChemistry tutorPhysics tutorBiology tutorEnglish tutorGCSE tutorsA level tutorsIB tutorsPhysics & Maths tutorsChemistry & Maths tutorsGCSE Maths tutors

CLICK CEOP

Internet Safety

Payment Security

Cyber

Essentials

MyTutor is part of the IXL family of brands:

IXL

Comprehensive K-12 personalized learning

Rosetta Stone

Immersive learning for 25 languages

Wyzant

Trusted tutors for 300 subjects

Education.com

35,000 worksheets, games, and lesson plans

Vocabulary.com

Adaptive learning for English vocabulary

Emmersion

Fast and accurate language certification

Thesaurus.com

Essential reference for synonyms and antonyms

Dictionary.com

Comprehensive resource for word definitions and usage

SpanishDictionary.com

Spanish-English dictionary, translator, and learning resources

FrenchDictionary.com

French-English dictionary, translator, and learning

Ingles.com

Diccionario ingles-espanol, traductor y sitio de apremdizaje

ABCya

Fun educational games for kids

© 2025 by IXL Learning