chapter 2 - the periodic table Flashcards
how many elements in the periodic table
118 elements
how did Dimitriv Mendeleev arrange the P.T
arranged by atomic mass and organised them into groups and periods due to the realisation of similar chemical properties
how are chemical properties determined
by the outer shell electrons
periods
- are horizontal groups
- corresponds to the filling of a shell eg. a period 3 element has three electron shells
groups
- vertical columns
- the group no. corresponds to the number of valence electrons eg. period2 element has 2 valence electrons
where are the s-block elements
group 1 and 2 including helium
- group 1 elements have outer shell s1
- group 2 elements have outer shell s2
where are the p-block elements
group 13-18
- the elements have their valence electrons in the p sub-shell, going across to 6 at g18
where are the d-block elements
group 3-12, transition metals
- these elements have their valence electrons progressively filled in the d sub-shell
where are the f-block elements
the lanthanoids and actinoids
- have valence electrons in the f sub-shell
what is core charge/nuclear charge
is a measure of the attractive force felt by the valence shell electrons towards the nucleus
how to calculate core charge
protons - inner shell electrons
across a period core charge
increases
down a group core charge
remains constant
what is the shielding effect
going down a group there is more shells being filled, these filled shells act as shields
across a period the shielding effect
remains constant
down a group the shielding effect
increases
ionisation energy
- increases across a period
- increases up a group
electronegativity
- increases up a group
- increases across a period
atomic radius
- increases down a group
- increases from right to left across a period
metallic character
- the most reactive/metallic element is francium
- the least reactive/metallic elements is helium
G1 & G2 are the
alkali earths
G17 are the
halogens
G18 are the
noble gases
