Periodicity Flashcards
Give an example of a physical and chemical property.
Physical property is melting and boiling point.
Chemical property is reactivity.
What is the periodicity?
The repeating patterns of physical and chemical properties in the periodic table due to their electronic confuguration.
What does the reactivity of metals depend on?
How much energy is required for them to lose their electrons (ionisation energy)
What is first ionisation?
The amount of energy needed to remove 1 mole of electrons from one mole of gaseous atoms to produce one mole of gaseous 1+ ions.
Eg: X(g) – X(g)+ + e-
Is first ionisation endothermic or ectothermic?
It is endothermic. Energy needs to be put in to remove the electron due to the attraction between the negatively charged electron and positive neucleus.
How does first ionisation energy change ACROSS a period? Why?
It increases. This is because the nucleus gets more positive so the electrons in the outer shell are more attracted to the nucleus
The atomic radius decreases across a period as the nuclei are more positive across a period, so the electron shells are held closer to the nucleus.
The shielding stays about the same (no. e- and subshells don’t increase much).
As a result a greater amount of energy is needed to remove an electron from the outer shell.
What is the exception to increasing first ionisation energy across a period?
When the following element has its outer electron in a higher energy level orbital. Less energy will be needed to remove that.
Eg: Beryllium - Boron
Oxygen has a lower 1st ionisation energy than nitrogen because its last electron is paired in an orbital whereas nitrogen’s isn’t. so oxygen’s outer electron is repelled by its pair, so less energy is needed to remove it.
What is shielding and what is its effect?
Shielding is the presence of many electrons between the outer electron and the nucleus of an atom, due to subshell number. Increased shielding repels the outer nucleus, shielding the positive charge of the nucleus. So it is less attracted to the nucleus.
How does first ionisation energy change DOWN a group?
It decreases due to increasing atomic radius and shielding, so there is less attraction between the outer electron and its nucleus as we go down the group.
Why is successive ionisation energy higher than first ionisation energy?
Because electrons are not all the same distance from the nucleus. If the first e- is removed from an p subshell and the second is removed from a s subshell, the successive ionisation energy will be higher as the s subshell is closer to the nucleus so there is greater attraction that needs to be overcome.
What are the three factors affection ionisation energy?
Atomic radius, nuclear charge and shielding.
Describe the bonding in metals.
The elctrostattic attraction between cations and delocalised electrons in giant lattice.
Conduct electricity due to delocalised e- able to carry a charge.
High melting and boiling points.
What are the examples of giant covalent lattice structures?
Diamond, Graphite, Graphene, Silicon.
All bonded atoms via covalnt bond. High melting and bouiling points.
Dont’t conduct except graphite and graphene (overlapping p orbitals with delocalised electrons).
How does melting point change across period 3?
Increases to Silicon due to giant metallic and giant covalent lattices. In the giant metallic (Mg+ till Al3+) ions attracted to delocalised e-. Higher ion charge = greater attraction.
In giant covalent, lots of covalent bonds which are stronger than metallic bonds.
From phosphorous (P4) onwards they only make simple covalnt structures with only weak intermolecular forces. More atoms in simple covalent structure and more electrons = stronger imtermolecular forces (hence sulfur, S8, has a higher melting point.
