Periodic Table Flashcards
How did early chemists arrange elements ? why was this discarded?
- Basis of valency , metallic and non metallic character
2. elements showed variable valency and dual character
Groups of three elements as grouped by Dobereiner are called ______
Triads
What was the specialty in Dobereiner’s triads?
The avg of first and last element’s atomic weight = atomic weight of middle term
Why was Dobereiner’s method discarded?
it did not hold true for all elements
Newland arranged elements in series of _____
8
what was Newland’s Law of Octaves?
Properties of every 8th element is a repetition of the first
Why was Newland’s method discarded?
It did not leave spaces for undiscovered elements
In what form did Mendeleev arrange the elements and what did he call it?
In the form of a table called Mendeleev’s periodic table
What law did Mendeleev state?
Properties of elements are periodic functions of their atomic weights
Why was Mendeleev’s method discarded?
did not justify position of certain elements, rare earths and isotopes
Who came closest to achieving the periodic table which we use today?
Mendeleev
Who was the only one to arrange on the basis of atomic number and not weight?
Robert moseley
Who founded today’s modern periodic table ?
Robert Moseley
State the modern periodic law
Physical and chemical properties of elements are periodic functions of their atomic.no
What is the fundamental property of an element
Atomic number
Group 18 in Modern periodic table is known as _____ and consists of _______
Zero group , Inert/Noble gases
Group 1,2,13 to 17 in the Modern periodic table are called ___ elements
Normal
Group 3 to 12 in the Modern periodic table are called ______ elements
Transition elements
How many periods are there in the Modern periodic table ?
7
How many groups are there in the Modern periodic table ?
18
What does period number signify
No. of electron shells in an element
Non metals are placed in the ______ corner of the periodic table
Upper right
Name a non metal which is solid at room temp
Iodine
Name a non metal which is in liquid state at room temp
Bromine
Name two non metals which are in the gaseous state at room temperature
Fluorine, Chlorine
Transition metals are placed in the ___
Middle
Transition from metallic to non metallic character is seen __________( across a period or down a group)
Across a period
Transition metals are _____( heavy or light) metals
Heavy
Valence electrons _____ as we move across a period
increase one by one
non metallic character _____( increases/decreases) along a period
Increases
What are bridge elements ?
Elements which show similarity in properties diagonally with period of next group
Period 2 elements are said to be bridge elements
Which period consists of typical elements
3
Why r period 3 elements called typical elements?
The elements of period 3 summarises the properties of their respective groups hence they r called typical elements
state the bridge and typical elements which are similar in properties
Li - Mg
Be - Al
B - Si
Periodicity in properties occur after a difference of ___.___.____._____ in atomic numbers due to recurrence of ____________
2,8,18 or 32
similar valence shell configuration
What does group number signify ?
no. of valence electrons in an element
Lanthanides are ____
rare earths
Actinides are ____
radioactive
Metallic character _____ down a group
increases