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# **Note:** * Mass of neutron (mn) = Mass of proton (mp) * Mass of electron (me) = 1 (mp or mn) * In an atom Mn > Mp >>> me if option is given [charge one = 1 charge on proton] ## Atomic no (Z) & mass no. (A) * Number of protons present in an atom * Number of protons + neutrons present in atom # (A...

# **Note:** * Mass of neutron (mn) = Mass of proton (mp) * Mass of electron (me) = 1 (mp or mn) * In an atom Mn > Mp >>> me if option is given [charge one = 1 charge on proton] ## Atomic no (Z) & mass no. (A) * Number of protons present in an atom * Number of protons + neutrons present in atom # (Atomic no.18 (Mass no.18) & (No. of electron, proton a neutron) always whole no. in integer. ## Representation of Atom:- * Atomic no. (superscript) (upward) * Mass no. (subscript) (down) * Symbol of atom **Represent an atom by neutron and proton not by electrons because variable** ### Atoms (for finding electron in atom) #### Isolated/Neutral/on charge atom No. of e = No. of protons #### Anion Formally gain less e No. of e = No. of p #### Cations 100% formally formed by gain of e No. of e = No. of p