Classification of Elements and Periodicity in Properties

Dobereiner's Law of Triads

the atomic mass of the central atom is the arithmetic mean of the atomic masses of the other two elements

AEB de Chancourtois

Telluric Helix

Newland's Law of Octaves

In a set of eight elements, the 1st and 8th element have similar characteristics.

worked for lighter elements only, up until Ca

Lothar Meyer

1. plotted graph between atomic volume and atomic weight

2. most electropositive elements at peaks of curves

3. less strongly electropositive elements occupy the DESCENDING portion of the curves

4. most electronegative elements occupy the ASCENDING position of the curves

5. transition metals occupy the TROUGHS of the curves

"the properties of elements are a periodic function of their atomic weights."

mendeleev

eka-aluminum

Gallium

eka-silicon

germanium

"the physical and chemical properties of elements are periodic functions of their atomic numbers."

Henry Moseley

What concept is the modern Periodic table based on

Bohr-Bury concept

How many periods are on the periodic table?

7

How many groups are on the periodic table?

18

Number of elements in each period

1st period: 2
2nd period: 8
3rd period: 8
4th period: 18
5th period: 18
6th period: 32
7th period: not complete, can fit 32

pseudo transition elements

Zn, Cd, Hg

Lanthanides

Ce(58) - Lu (71)

Actinoids

Tho(90) - Lr (103)

metalloids (semimetals)

silicon, arsenic, germanium, tellurium, antimony

Are covalent radii are van der Waals radii larger

van der Waals radii

van der waals, covalent and metallic radii size

van der Waals > metallic > covalent

which elements have the largest radii in their respective periods

nobel gases

Is ionization energy endothermic or exothermic?

endothermic

Does B have a higher ionisation enthalpy or does Be have a higher ionisation enthalpy

Be

(exception)

removing electron from 2s is harder than removing from 2p

Does beryllium show positive electron gain enthalpy

yes

Does neon show negative electron gain enthalpy

no

does nitrogen show positive electron gain enthalpy

yes

does fluorine or chlorine have a higher electron gain enthalpy

florine

which has a higher negative electron gain enthalpy, sulphur or oxygen

sulphur

Electronegativity (Mulliken scale)

(IE1 + IE2)/ 2

Pauling Scale of Electronegativity

Mulliken scale/ 2.89j

Lithium has a diagonal relationship with

Mg

Beryllium has a diagonal relationship with

Al

Boron has a diagonal relationship with

Si

Covalency of first members of each group

4

Which elements form pπ-pπ bonds

all of the first members of the p-block elements form these bonds with themselves, or with other first members of other groups of p-block

Cl₂O₇ + H₂O

2HClO₄
(perchloric acid)

Na₂O + H₂O

2NaOH

Most electropositive element

Caesium

most dense element

iridium

best electrical conductor

silver

which element shows the maximum number of isotopes

tin

in each period, second IE is greatest in which group

1st

in each period, third IE is greatest in which group

2nd

which element has the highest IE

He

Which element has the highest MP among metals

W

among all the elements, which has the highest MP

diamond (C)

elements of F block belong to which group

3

radioactive lanthanide

promethium (61)

element 118

last element in group 18
(period 7)

how many elements are in 4f and 5f each

14