— Elements contain only one type of atom
— Atoms consist of a nucleus and rings (electrons shells) around
— All transition elements (ones in the middle of the periodic table)
— Around 90 elements + around 30 artificial (unstable)
— Left of the little staircase = metals
— Right of the little staircase = non-metals
— Groups = Columns of the periodic table
— Elements in the same groups have similar properties
— Proton no. > 93 = artificial element
<aside> 💡 Atoms can be identified by their proton numbers
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— isotopes - atoms of the same element with different nucleon numbers