periodicity Flashcards
(26 cards)
what is the definition of 1st ionisation energy
the first ionisation energy of an element is the energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions
what are the factors affecting ionisation energy
-atomic radius
-nuclear charge
electron shielding
how does atomic radius affect ionisation energy
the greater the atomic radius the smaller the nuclear attraction experienced by the outer electron
how does nuclear charge affect ionisation energy
the greater the nuclear charge (more protons in the nucleus), the greater the attractive force on the outer electrons
how does electron shielding affect ionisation energy
-inner shells of electrons repel the outer shells
-this repelling effect is called electron shielding
-the more inner shells there are, the larger the shielding effect and the smaller the nuclear attraction experienced by the outer electrons
what is effective nuclear charge
-what the electron actually experiences in terms on the charges and forces acting on them
what does atomic radius do as you go down a group
it increases as outer electrons are further from the nucleus. attractive forces are weaker and the energy required to remove an electron decreases
what happens to shielding as you go down a group
-increases as there’s more shells between the nucleus and outer shell.
-the attractive force is weaker.
-energy required to remove an electron decreases
what happens to ionisation energy as you go down a group
decreases
what happens to ionisation energy as we go across a period
increases as more energy is required to remove an outer electron
what happens to nuclear attraction when going across a period
increases as there is an increasing number of protons in the nucleus
what happens to electron shielding when going across a period
marginally decreases
why is aluminium an exception
-aluminium has a lower ionisation energy than magnesium which doesn’t fit the increasing trend
-as the outer most electron sits in a higher energy sun shell slightly further from the nucleus than the outer electron in magnesium
has a 3p1 subshell
why is sulfur an exception
-sulfur and phosphorus have outer electrons in the 3p orbital so shielding is the same
-but sulfur involves removing an electron from an orbital with 2 electrons in
-as electrons repel eachother so less energy is needed to remove an electron from an orbital with 2 than 1
why does removing an electron from an orbital with 2 electrons effect ionisation energy
as electrons repel so less energy is needed to remove an electron from the orbital
why does an electron in a different orbital effect ionisation energy
as the outer most electron sits in a higher energy sub shell slightly further from the nucleus
what is successive ionisation
the removal of more than one electron from the same atom
why is there jumps in a successive ionisation graph
as removing electrons from shells closer to the nucleus is harder
how does melting point increase
as metal ions have an increasing positive charge, increasing number of delocalised electrons and smaller ionic radius. this means a stronger metallic bond
why does silicon have a high melting point
-it has a giant covalent structure
-many strong covalent bonds hold the silicon atoms together
-a large amount of energy is needed to overcome these strong covalent bonds
why does phosphorus have a low melting point
-weaker simple molecular structure
-weak small induced dipole-dipole forces
why does sulfur has a higher melting point than phosphorus
-a larger simple molecular structure
-it has larger induced dipole-dipole forces
why does chlorine have a low melting point
-smaller simple molecular structure
-it has smaller induced dipole-dipole forces
why does argon have a low melting point
as it exists as individual atoms
has smaller induced dipole-dipole forces
