Chapter 1,2,3 Questions Flashcards
Explain why iodine is solid at room temperature while chlorine is a gas.
Iodine and chlorine are non-polar. Melting point is determined by strength of the dispersion forces. Iodine is a larger molecule which indicates that it has stronger dispersion forces.
Explain why metals are excellent conductors of electricity but ionic solids are non-conductors?
- Metals - delocalised electrons.
- Ionic solids - Anions and cations are held in fixed positions by strong electrostatic forces. No mobile charged carriers
Explain why methanol (CH3OH) dissolves in water but petrol (C8H16) does not?
- Methanol will form hydrogen bonds with water and this significant attraction between the molecules will favour mixing.
- Petrol is non-polar, therefore it only forms dispersion forces with H2O molecules which is not strong enough to overcome the hydrogen bonds between H2O molecules.
Why is the boiling point of Radon much higher than Neon?
Because radon has a higher number of electrons over all, which indicates that it forms more dispersion forces and this will require more energy to pull apart the bonds that will form.
HCL has a BP if -85•C and HI has a BP of -35•C. HCL is the most polar molecule and dipole-dipole forces are normally stronger than dispersion forces. So why is the BP of HI > BP of HCL?
Iodine has a lot more electrons therefore it has a lot more dispersion forces.
Explain the boiling point trends in the graph. (Pg80) HNDJISNXD
Most of the compounds’ boiling point gradually increases as it goes down the periodic table, however the hydrogen bonds have an extremely high boiling point compared to compounds which involve elements located in the same group and this is because N, O, D have the highest electronegativity. Hydrogen bonds also have a high boiling point in general.
Explain why Diamond doesn’t conduct electricity.
Diamond has covalent network bonding the electrons are highly localized in the covalent bond and are therefore not available to act as charge carriers.
Explain why the atomic radius of Al is smaller than the atomic radius of Mg?
Aluminium has a higher number of protons which means that it has a higher nuclear charge this will result in greater forces of attraction between the electrons and the nucleus. As tj electrons are pulled closer to the nucleus the atomic radius becomes smaller.
Why is the atomic radius or calcium larger than that if magnesium?
Both calcium and magnesium have the same number of electrons but different number if energy levels. Calcium has a higher number of energy levels, (greater shielding) which results in less force of attraction and a smaller atomic radius, which will require a higher first Ionisation energy.
Dramatic energy increase MJ Mol-1.
The first 4 electrons requires less energy because it’s further away from the nucleus. The dramatic increase indicates that to remove an electron from the inner shell requires a higher nerdy because the the force of attraction towards the nucleus is higher. Jumping of Ionisation energies of 4 and 5 indicates a different energy level.
Account for the differences in ionization energies for atoms A and B.
JFBSUANSBSHA
B had more protons in the nucleus, stronger attraction between nucleus and outermost electrons, therefore more energy is required.
•similar atomic size & shielding effect,
Why is the boiling point of H2Te greater than that of H2S?
Te has a higher molecular mass, therefore it has more dispersion forces which will result in a higher BP.
Why is the BP of H2O much higher than that of H2Te?
H2O forms a strong hydrogen bond and H2Te has a weak dipole-dipole because Te is slightly more electronegative than hydrogen. And the high molecular weight of H2Te gives rise to dispersion forces but those forces of attraction are weaker than H2O.
