inorganic 1 - periodicity Flashcards
(14 cards)
What are elements classified as?
s, p or d block.
How are elements classified?
They are classified according to which orbitals the highest energy electrons are in.
What is the trend in atomic radius across period 3?
The atomic radius decreases across the period.
Why does the atomic radius decrease across period 3?
Across the period there are more protons and the outer electron is in the same shell. Therefore, there is a stronger pull due to more protons pulling the electrons closer to the nucleus.
What is the trend in the first ionisation energy across period 3?
There is a general increase however, a dip from group 2 to 3 and a dip from group 5 to 6.
Why is there a general increase in first ionisation energy across period 3?
There are more protons across the period and so there is a greater attraction between the positive nucleus and the negative outer shell electron. Therefore, more energy is required to remove an electron.
Why is there a dip in the first ionisation energy between group 2 and 3?
The magnesium electron is from an s orbital whereas aluminium is from a p orbital. P orbitals have more energy than s orbitals and so they lose electrons more easily.
Why is there a dip in first ionisation energy between group 5 and 6?
Phosphorus is from an orbital with one electron whereas sulfur is from an orbital with 2 electrons and so there is more electron-electron repulsion meaning electrons are lost more easily.
What is the trend in electronegativity across period 3?
Across the period there are more protons and so the elements have a smaller atomic radius. Thus there is a stronger attraction between the positive nucleus and the two electrons in a covalent bond.
What is the trend in melting points across period 3?
Giant covalent element>metallic elements>simple molecular elements>monatomic element.
Why are the melting points of the metallic elements in period 3 high?
They are high as they have strong metallic bonding. Al>Mg>Na as from Na to Al have smaller atoms and more delocalised electrons/ions.
Why is the melting point of Si very high?
The melting point of Si is very high as it has giant covalent bonding. This means many strong covalent bond need to be broken to melt which requires lots of energy.
Why are the melting points of the simple molecular elements in period 3 low?
They are low as they are simple molecular with weak VDW’s forces between molecules. S8>P4>Cl2 as S8 has the most electrons (it contains more molecules) and so there are strong VDW’s forces between molecules.
Why is the melting point of Ar very low?
Ar is monatomic so it’s melting point is very low as it contains very weak VDW’s forces between atoms.
