development of the periodic table Flashcards
how did Mendeleev arrange elements in the periodic table
in order of increasing atomic mass and so that elements with similar properties were in the same group
why weren’t values for atomic masses accurate in Mendeleevs table
isotopes weren’t discovered
what did Mendeleev do in his periodic table
left gaps which corresponded to his predictions of undiscovered elements. he also made predictions about the properites of these undiscovered properties
why are some elements made synthetically
they dont exist naturally
what were the first two elements that were made synthetically
neptunium and plutonium
how were the two synthetic elements formed
by bombarding uranium atoms with neutrons
what is the modern periodic table based on
the one drawn by Mendeleev
what determines the place of an element
the atomic number
what are the four blocks of the periodic table
s, p, d, f (every element is organised into these blocks except hydrogen)
what do elements in the same block show
similarities
where are non metals and metals placed
metals in s block and non metals in p block
vertical columns =
groups
horizontal rows =
periods
what is the occurence of periodic patterns called
periodicity
what happens when elements are melted or boiled
bonds between individual atoms or molecules (intermolecular forces) must be overcome
the higher the strength of the intermolecular forces =
the higher the melting point/boiling point as more energy is required to overcome these forces
what do the number of outershell electrons determine
the group number
what do number of shells determine
the period number
what determines the chemical properties of an element
the outer electrons in the incomplete shells
what do noble gases have
stable arrangement of atoms. full closed outer shell
which elements are in the s block
groups 1 and 2
which elements are in the p block
groups 3, 4, 5, 6, 7, and 0
what is important about Mendeleevs periodic table
it organised elements based on their atomic weight and chemical properties. this arrangement allowed Mendeleev to predict the properties of elements that were yet to be discovered. the arrangement of in the table reflects the structure of their protons, neutrons and electrons
how is the modern periodic table arranged
in order of increasing atomic number. elements with the same number of electron shells are arranged in horizontal rows and elements with similar properties are arranged in vertical columns.
