3.2.1 - Periodicity Flashcards
What is periodicity?
The repeating pattern of physical/chemical properties going across the periods.
Explain the atomic radius as we go across period 3.
Atomic radii decreases as we go along period 3 due to the increased number of protons, which creates a stronger attraction to the nucleus.
What do the first 3 elements have in period 3 (bonding)?
Metallic.
Explain the boiling point trend in period 3.
General increase in melting points as we go across period 3 due to increased delocalised electrons and a smaller ionic radius.
Why does silicon have the highest boiling point in period 3?
Silicon has macromolecular, giant covalent structures with many strong covalent bonds, requiring more energy to break.
Why does phosphorus have a smaller melting point than silicon?
Phosphorus has a weaker simple molecular structure determined by van der Waals forces, which are much weaker.
Explain why chlorine and argon have lower melting points.
Chlorine and argon have simple molecular structures with weak intermolecular forces.
What is formed when magnesium burns in oxygen?
A bright white flame, producing a white solid.
Suggest one property of aluminium oxide that causes aluminium to resist corrosion in water.
It is insoluble.
Write an equation for the reaction between aluminium oxide and HCl.
Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O
Write an equation for the reaction between aluminium oxide and an excess of aqueous sodium hydroxide.
Al₂O₃ + 2NaOH + 3H₂O → 2NaAl(OH)₄
Explain why lithium oxide has a higher melting point than sodium oxide.
Lithium ion is smaller than the sodium ion, attracting the O²⁻ ion more strongly.
State the type of bonding in basic oxides and explain why.
Ionic; they contain O²⁻ ions which react with water to form OH⁻ ions.
Suggest why silicon dioxide is described as a basic oxide.
It reacts with bases.
What happens to periodicity across period 3?
Atomic radius decreases due to an increase in protons, resulting in a stronger attraction to the nucleus.
Explain what happens with the ionisation energy between magnesium and aluminium.
Aluminium has a reduced ionisation energy due to increased shielding and being further from the nucleus.
What is the trend in electronegativity?
Generally increases across a period and decreases down a group, but usually not for the last element.
Why do P₄O₁₀ and SO₂ have low melting points?
They form simple molecular structures with weak intermolecular forces, making the bonds easy to break.
Give 4 physical properties of silicon dioxide.
Brittle, non-conductor, hard, insoluble.
Write the equation for how sodium reacts with oxygen.
4Na + O₂ → 2Na₂O
Write the equation for how magnesium reacts with oxygen.
2Mg + O₂ → 2MgO
Write the equation for how aluminium reacts with oxygen.
4Al + 3O₂ → 2Al₂O₃
Write the equation for how phosphorus reacts with oxygen.
4P + 5O₂ → P₄O₁₀
How are elements classified into s, p, and d blocks on the periodic table?
Elements are classified based on the orbitals in which the highest energy electrons reside.
Explain the trend in atomic radii across a period in the periodic table.
Atomic radii decrease from left to right due to increasing nuclear charge pulling electrons closer.
Describe the general trend and exceptions in the first ionisation energies across Period 3.
First ionization energies generally increase across a period, with exceptions between Mg and Al, and between P and S.
Explain the trend in melting and boiling points across Period 3 from Na to Ar.
Na to Al show increasing melting points due to stronger metallic bonding; Si has a very high melting point due to its macromolecular structure.
How are the trends in Period 2 similar to those in Period 3 regarding physical properties?
Both periods show similar trends in atomic radius, ionization energy, and melting points.
Why do elements like boron and carbon have much higher melting points compared to their neighbors?
Boron and carbon form macromolecular structures with strong covalent bonds.
How do the electron configurations of elements influence their chemical and physical properties?
The electron configuration determines an element’s reactivity, ionization energy, and types of bonds it can form.
Define periodicity in the context of the periodic table.
Periodicity refers to the repeating pattern of chemical and physical properties of elements across different periods.
Which block does molybdenum belong to in the periodic table?
Molybdenum is classified as a d-block element.
Which element in Period 3 has the highest melting point?
Silicon has the highest melting point among the elements in Period 3.
Which ion has the largest radius among the given options?
O²⁻ has the largest radius.
Which element has a first ionisation energy lower than that of sulfur?
Selenium has a lower first ionisation energy than sulfur.
What is the equation for the reaction of phosphorus(V) oxide with water, and suggest a possible pH for the solution?
P₄O₁₀ + 6H₂O → 4H₃PO₄
The solution is likely to be acidic.
What is the formula of a hydroxide of an element in Period 3 that is used in medicine?
The formula is Mg(OH)₂, which is magnesium hydroxide.
Which element in Period 3 has the largest atomic radius?
Sodium has the largest atomic radius in Period 3.
