development of the periodic table

Question 1

how did Mendeleev arrange elements in the periodic table

Answer 1

in order of increasing atomic mass and so that elements with similar properties were in the same group

Question 2

why weren’t values for atomic masses accurate in Mendeleevs table

Answer 2

isotopes weren’t discovered

Question 3

what did Mendeleev do in his periodic table

Answer 3

left gaps which corresponded to his predictions of undiscovered elements. he also made predictions about the properites of these undiscovered properties

Question 4

why are some elements made synthetically

Answer 4

they dont exist naturally

Question 5

what were the first two elements that were made synthetically

Answer 5

neptunium and plutonium

Question 6

how were the two synthetic elements formed

Answer 6

by bombarding uranium atoms with neutrons

Question 7

what is the modern periodic table based on

Answer 7

the one drawn by Mendeleev

Question 8

what determines the place of an element

Answer 8

the atomic number

Question 9

what are the four blocks of the periodic table

Answer 9

s, p, d, f (every element is organised into these blocks except hydrogen)

Question 10

what do elements in the same block show

Answer 10

similarities

Question 11

where are non metals and metals placed

Answer 11

metals in s block and non metals in p block

Question 12

vertical columns =

Answer 12

groups

Question 13

horizontal rows =

Answer 13

periods

Question 14

what is the occurence of periodic patterns called

Answer 14

periodicity

Question 15

what happens when elements are melted or boiled

Answer 15

bonds between individual atoms or molecules (intermolecular forces) must be overcome

Question 16

the higher the strength of the intermolecular forces =

Answer 16

the higher the melting point/boiling point as more energy is required to overcome these forces

Question 17

what do the number of outershell electrons determine

Answer 17

the group number

Question 18

what do number of shells determine

Answer 18

the period number

Question 19

what determines the chemical properties of an element

Answer 19

the outer electrons in the incomplete shells

Question 20

what do noble gases have

Answer 20

stable arrangement of atoms. full closed outer shell

Question 21

which elements are in the s block

Answer 21

groups 1 and 2

Question 22

which elements are in the p block

Answer 22

groups 3, 4, 5, 6, 7, and 0

Question 23

what is important about Mendeleevs periodic table

Answer 23

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

Question 24

how is the modern periodic table arranged

Answer 24

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.

Question 25

what was Doberieners law of triads

Answer 25

when elements are arranged in order of increasing atomic masses, groups of three elements having similar chemical properties are obtained. the arithmetic mean of atomic masses of the 1st and 3rd element would be approx equal to the atomic mass of the 2nd element

Question 26

what was the limitations of the law of triads

Answer 26

newly discovered elements did not fit in the triads. only 5 triads were identified. even several known element did not fit in the triads

Question 27

what was newlands law of octaves

Answer 27

the 62 elements were arranged based on their atomic masses. every 8th elements had similar properties. every 8th was comparable to the first

Question 28

what was the limitations of the law of octaves

Answer 28

several elements were fit into the same slots in Newlands periodic classification. elements with disimilar properties were grouped together. any elements discovered later could not fit in the octave pattern