Atomic Chemistry Flashcards
Chapters 1-4
Explain the trend in atomic radius across a period
Decreases due to increasing nuclear charge since no. of shells are equal
Explain the trend in ionic radius amongst anions and cations across a period
Cation and anion radii decrease because of increasing nuclear charge.
Why do non-metals have greater atomic radius than metals, and anions have greater radius than their neutral counterparts?
Anions and non-metals have greater radii than their neutral counterparts and metals respectively due to more electrons, increased repulsion and consequently, wider clouds
What makes an atom in ground state different from one in excited state
Atoms in ground state have all their electrons in orbitals that keep the total electron energy at it’s lowest. Electrons cannot be transferred between orbitals to reduce total electron energy. Excited atoms though have total electron energy levels that can be reduced further through the transfer of electrons between orbitals.
What is a free radical and how different is it from an ion
Free radicals have one or more unpaired electrons and are usually formed from split up covalent bonds. Despite their unpaired electrons, they are uncharged but are still unstable. Ions on the other hand are charged and relatively more stable than radicals. Radicals and cations both gain electrons to stabilise themselves
What is the order of filling subshells from 1s to 4p?
1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p
Why does ionisation energy generally increase across a period?
Increase in nuclear charge
Why is Boron’s ionization energy lower than expected
It’s valent electron fills a p orbital that’s a little further away from the nucleus as compared to the valent electron in Beryllium
What is the formula for percentage yield?
(Actual yield/ Calculated yield) * 100
What are the factors that influence electronegativity?
Nuclear charge, shielding and atomic radius
How are Al2Cl6 molecules formed
Al2Cl6 molecules are formed when AlCl3 molecules attach themselves to each other in the gaseous states at relatively lower temperatures. 1 Chlorine atom from each of the AlCl3 molecules forms a dative covalent bond with the aluminium from the other molecule. (Covalency may arise from little difference in electronegativity)
What type of bonds are single, double and triple covalent bonds comprised of?
Single - one sigma
Double - one sigma, one pi
Triple - one sigma, two pi
What forms of hybridisation are in the following molecules: ethane, ethene, nitrogen gas
sp^3, sp^2 and sp
Why are double bonds and triple bonds shorter and stronger than single bonds?
More bonds means higher electron density and hence more attraction between bonding electrons and nuclei. This calls for more energy to break bonds.
Explain hydrogen bonding
If F, O or N is bonded to hydrogen, an extremely polar bond is formed due to the difference in electronegativity.
The presence of a lone pair with a negative charge allows for electrostatic attraction between the hydrogen and this lone pair.
The strength of this bond is 1/5 that of a covalent bond
