Periodicity Starter

Which of the following statements is NOT correct?

• The atomic radii of the elements decrease across period 3

• The first ionisation energies of the elements generally increase across period 3

• The melting points of the elements increase across period 3

Which of the folowing correctly lists the atomic radii (in nm) of the elements Na, Mg, Al and Si

• 0.190, 0.145, 0.118, 0.111

• 0.111, 0.118, 0.145, 0.190

• 0.111, 0.145, 0.118, 0.190

• 0.190, 0.118, 0.145, 0.111

Which of these statements BEST explains the decrease in atomic radii across period 3 fro sodium to argon?

• Shielding increases, pulling electrons closer to the nucleus

• Shielding decreases, pulling electrons closer to the nucleus

• The effective nuclear charge increases, pulling electrons closer to the nucleus

Tags

NGSS.HS-PS1-1

How doe shielding vary across period 3 from sodium to argon?

• It increases significantly

• It decreases significantly

• There is no significant variation

Tags

NGSS.HS-PS1-1

Which of these statements explains why the first ionisation energy of sodium is less than that of magnesium?

• The effective nuclear charge is less in sodium, so more energy is required to remove an electron

• The effective nuclear charge is less in sodium, so less energy is required to remove an electron

• The effective nuclear charge is less in magnesium, so more energy is required to remove an electron

Which of the following elements has a first ionisation energy that is lower than expected?

• magnesium

• aluminium

• phosphorous

Which of these statements is the BEST explanation for why the first ionisation energy of aluminium is lower than that of magnesium?

• The highest energy electron in aluminium is removed from a 3p orbital as opposed to a 3s orbital

• There is mutual repulsion between 3p electrons in aluminium

• The aluminium ions have a higher charge density than magnesium

Which of these statements is the BEST explanation for why the first ionisation energy of sulfur is lower than that of phosphorous?

• The highest energy electron in sulfur is removed from a 3p orbital as opposed to a 3s orbital

• There is mutual repulsion between the two paired electrons in the 3p orbital in sulfur

• There is mutual repulsion between the two paired electrons in the 3s orbital in phosphorous

• There is no pair of electrons in the 3p orbital in phosphorous

Which of the following elements has a covalently-bonded macromolecular structure similar to diamond?

• silicon

• sulfur

• phosphorus

Which of these statements best explains why chlorine has a lower melting point than sulfur?

• Chlorine atoms have a greater relative atomic mass than sulfur

• Chlorine atoms have weaker covalent bonds than sulfur atoms

• Chlorine molecules are held together by weaker van der Waals forces than sulfur molecules