7.1 & 7.2 the periodic table and Ionisation energies Flashcards
The development of the periodic table…
Aristotle:everything was
made of 4 elements, earth, water, air and fire.
Döbereiner:‘law of triads’ Cl Br I
John Newlands:devise a Periodic Table of the elements arranged in order of their relative atomic masses. ‘Law of octaves.’
Mendeleevarranged the elements in increasing
mass order but left ‘gaps’
The Modern Periodic Table is arrangged in increasing….
atomic number
periodic table
groups share similar …… properties because…..
Elements in the same group
have similar** chemical properties **as they have the same no. of electrons on the outer shell.
Similar elements are placed in vertical groups so any element within a group has the same number of electrons in the outer shell which explains the similarities in chemical behaviour.
periods in the periodic table share similar…..properties beacuse…..
chemical and physical patterns
The number of the period is the number of the highest energy electron shell of that element.
Periods often show gradual changes in properties. These patterns are repeated across each
Period. This is called periodicity.
define
Periodicity
Periodicity is a regular periodic variation of properties of elements with atomic number and position in the Periodic Table.
Periodicity in electronic configuration:
The periodic table can be divided into blocks showing an elements highest energy sub-shell
define
ionisation energy
First ionisation energy is the energy required to remove 1 electron from each atom in
one mole of gaseous atoms of an element to form one mole of gaseous 1+ ions.
AN ATOM HAS AS MANY IONISATION ENERGIES AS IT HAS ELECTRONS
(In short, the energy required to remove 1 mole of electrons from 1 mole of gaseous
atoms to form one mole of gaseous 1+ ions)
First ionisation energy can be represented using an equation…
Na (g) –>Na+ (g) + e-
define
Second ionisation energy
Second ionisation energy is the energy required to remove 1 electron from each
1+ ion in one mole of gaseous ions of an element to form one mole of gaseous 2+ ions.
Factors affecting ionisation energy:
- atomic radius
- nuclear charge
- electron sheilding
whats the impact of an increasing
atomic radius on ionisation energy
IE decreases
the GREATER the distance between the nucleus and the outer electrons, the WEAKER the
nuclear attraction. Atomic radius has a large effect.
whats the impact of an increasing
nuclear charge on ionisation energy
IE increases
the MORE PROTONS contained in
the nucleus the GREATER the nuclear attraction.
whats the impact of an increasing
Electron shielding on ionisation energy
IE decreaes
negatively charged electrons that
are on the inner-shells cause repulsion with the
outer shell electrons – this is known as the shielding
effect. This REDUCES the attraction between the
nucleus and the outer shell electrons
Periodicity of what 4 properties
- electron configuration
- ionisation energy
- stucture
- melting point
the second ionisation energy produces a …. ion from a …. ion
2+ ion from a 1+ ion
ionisation energy and affinity
Ionization energy is the amount of energy it takes to remove an electron from an atom. Electron affinity is how much energy that is released when an atom gains an electron. They are in direct relation to each other, so atoms with high ionization energy will also have high electron affinity.
statethe trend in 1st ionisation energy
down a group
- atomic radius increaes
- more inner shells so sheilding increaes
- nuclear attraction on outer electrons decreaes
- first ionisation energy decreases
trend in 1st ionisation energy
across a period
- nuclear charge increases (more protons)
- Same shell no. similr sheilding
- nuclear attraction increases
- atomic radius decreases
- first ionisation energy increases
,exception to general trend
why is Berylium higher than boron?
if in doubt draw out
the outer electron in boron is in the 2p subshell wich is higher energy than 2s so further from the nucleus so has additional sheilding
,exception to general trend
why is oxygen lower than nitrogen?
if in doubt draw
the 2p subshell in oxygen has a paired electron orbital wich repel one another hense is easier to remove (nitrogen hace equal repulsion)
which three elments express giant covalent structure?
- B
- C
- Si
