Periodicity, Group 2 and Group 7 Flashcards
horizontal rows of elements are called ….
periods
vertical columns of elements are called…
groups
elements in a group have the same number of …
outer shell electrons
metals are ____ conductors of electricity
good
non-metals are _______ conductors of electricity
non
metalloids are ________ conductors of electricity
poor
s-block elements have their highest energy outer-shell electron in the _ orbital
S
Describe the trend in atomic radii across a period (5 marks)
Protons are added to the nucleus so nuclear charge increases.
Electrons are added to the same shell.
The nuclear attraction on the outer shell electrons increases across a period.
The electron shells are drawn inwards by the nucleus, making the atoms smaller.
so atomic radii decreases across a period.
Describe the trend in atomic radii down a group (5 marks)
The number of shells increases
The outer electron is added to a new shell which is further away from the nucleus.
The shielding effect by the inner shell electrons increases down a group.
The nuclear attraction decreases down a group
So the atomic radii increases down a group.
A substance has a high melting or boiling point if the bonds broken are (1). The structure of the substance is (2).
- Strong
- Giant
A substance has a low melting or boiling point if the bonds broken are (1). The structure of the substance is (2).
1.Weak
2. Simple
Across each period there is a sharp decrease in melting and boiling points between Group 4 and 5. Explain why.
Structures change from giant to simple.
Why is the boiling point of aluminium much higher than that of sulfur
Aluminium is a giant metallic structure whereas Sulfur is simple covalent.
Aluminium has stronger bonds, takes more energy to overcome and break the bond.
explain why Phosphorus (P4) has a higher boiling point than Chlorine (Cl2).
P4 has more intermolecular forces to break so more
energy is needed than Cl2 molecules. Whereas Cl2 is a smaller molecules so can break bonds quicker.
P4 has more electrons than Cl2.
Define first ionisation energy
First ionisation energy 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.
the more (1) in the nucleus, the greater the nuclear charge. The greater the nuclear charge, the stronger the nuclear (2) on the outer electrons. Therefore a higher nuclear charge means (3) energy would be needed to overcome the attraction between the nucleus and the outermost electron.
- proton
- attraction
- more
As the distance between the outmost electron and the nucleus increases, the attraction between them (1). The weaker the nuclear attraction, the (2) energy is needed to remove the outer electron
- decreases
- less
Electron shielding is the shielding between electrons in different (1) shells. This shielding effect reduces nuclear attraction. The more inner shells there are, the (2) the shielding effect and the (3) nuclear attraction.
- inner
- more
- less
First ionisation energy (1) down a group
there are (2) shells
more (3) effect ( from inner shell electrons)
the atomic radius (4).
the (5) on the outer shell electrons decrease
(6) energy is needed to remove the outer electron
- decreases
- more
- shielding
- increases
- nuclear attraction
- less
First ionisation energy (1) across a period
the outer electron fills the (2) shell so (3) stays the same.
the atomic radius (4)
therefore there is a greater (5) on outer electrons
(6) energy is needed to remove the outer electron.
- increase
2.same - shielding
- decreases
- nuclear attraction
- more
state and explain which element has the highest first ionization energy:
Carbon and Nitrogen
Nitrogen.
Nitrogen has a smaller atomic radius
But similar shielding
More attraction to the outer shell electron as it has more protons. More energy needed to break the nuclear attraction.
state and explain which element has the highest first ionization energy:
Potassium and Lithium
Lithium.
less electron shells, smaller atomic radius.
less shielding.
Nuclear attraction increases, more energy required to loose outer electron
State and explain which element has the highest first ionization energy:
Magnesium and Aluminium
Magnesium.
Aluminium outer electron lies in p-orbital, further from the nucleus.
less nuclear attraction
same shielding
aluminium looses outer electron easier.
State and explain which element has the highest first ionization energy:
Phosphorus and Sulfur
Phosphorus:
Sulfur has a pair of electrons in it’s orbital.
electron pair repels
easier to loose its outer electron
same shielding
Define successive ionization energies.
Successive ionization energies are a measure of the energy required to remove each electron in turn.
write an equation for the second ionization of sodium.
Na+(g) ——–> Na2+ (g) + e-
write an equation for the seventh ionization of bromine
Br6+(g) ———> Br7+ (g) + e-
explain why successive ionisation energies increase with ionization number. (4)
once an electron has been removed, there are the same number of protons but fewer electrons
proton : electron ratio increases
remaining electrons are more strongly attracted to the nucleus
more energy is needed to remove each electron in turn.