Question

The number of electron in an ion M3- will be atomic number =7

Answer 1

Answer:

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Answer 2

we have to find the number of electrons in an ion M³⁻ . atomic no of which is 7.

solution : before answering this question, let's remember some basic principles of an atom of an element.

• an atom of an element has equal no of protons and electrons.
• atomic no is the number of protons present in any atoms.
• if electrons are added to an atom, it will be negatively charged species. and the value of charge on it will be ( no of electrons - no of protons). for example, M²⁻ ion, means it has two extra electrons than its ground state.
• if electrons are removed from an atom, it will be positively charged species and the value of charge on it will be ( no of protons - no of electrons). for example, A¹⁺ ion, means one electron is removed from it.

let's come to the question,

atomic no = 7 = no of protons

for ground state,

   no of electrons = no of protons = 7

charge on ion is negative and that is -3. it means, three extra electrons in it than its ground state.

∴ no of electrons in ion  = no of electrons in ground state + 3

                                       = 7 + 3 = 10

therefore the number of electrons in the ion M³⁻ is 10.