atomic structure (chap3) -olevel pure chem

what is an atom

an atom is the smallest particle that can still have the chemical characteristics of an element

what is an ion

an ion is the particle formed when an atom or group of atoms gains or loses electrons, but the number of protons and neutrons remains the same

what is an isotope

isotopes are atoms of the same element that have the same proton (atomic) number but different number of neutrons.

they undergo the same kind of chemical reactions but may have different physical properties (eg diff boiling and melting point)

what are noble gases

• have full valence electron shells

• group 18th of the periodic table

• chemically unreactive

• monoatomic - exist as single atoms