7) PERIODICITY Flashcards
Who arranged the periodic table in the past?
Mendeleev
How is the periodic table arranged now?
-144 elements
-7 periods
-18 groups
What are the 3 factors in which the elements are arranged in the periodic table?
-atomic number
-groups
-periods
What do the positions of elements show?
The elements physical + chemical properties
How are the elements arranged according to atomic number?
-left —> right
-increasing atomic number
How are the elements arranged according to groups?
-elements in the same group have the same number of e- shells
-similar properties
what does a period show?
- the number of highest energy e-
Define periodicity
Repeating trend in properties of the elements
What are the 4 types of periodicity?
-electron configuration
-ionisation energy
-structure
-melting points
What are the 4 types of sub shells?
-s
-p
-d
-f
What is the trend across a period in electronic configuration?
1 e- increase between each element
What is the difference in electronic configuration down a group?
Elements in the same group have the same number of e- in each sub shell
Define first ionisation energy?
Energy required to remove 1 e- from each atom in 1 mole of a gaseous element
what are the factors that affect the ionisation energy?
-atomic radius
-nuclear charge
-electron shielding
what are the effects of the atomic radius on the ionisation energy?
greater distance = less nuclear attraction = decreased IE
what are the effects nuclear charge on the nuclear charge?
more protons = greater attraction = increased IE
what are the effects of electron shielding on the nuclear charge?
-more shields = less attraction = lower IE
what does successive ionisation energy mean?
as the number of e- removed increases = ion becomes more positive
what is the trend in first IE down a group?
decreases
why does the IE decrease down a group?
-atomic radius increases
-shielding increases
-nuclear attraction decreases
-IE decreases