Q5 Questions Flashcards
Atomic Number
The number of protons in the nucleus of an atom
Smaller Number
B — Cl bond
Polar or non-polar??
Polar
Unequal sharing of electrons between B and Cl
BCl3 molecule
Polar or non-polar??
Non-polar
Centres of positive and negative charge coincide
How did Mandeleev arrange the elements
According to atomic weight
There was a repeat of elements according to similar chemical properties
Who (about 1897) measured the ratio of charge to mass of the electron (e/m)
JJ Thompson
Who (about 1910) proved that the electrons in an atom reside in an electron cloud surrounding a small dense positive central nucleus
Ernest Rutherford
Who (about 1911) measured the charge on the electron
Robert Millikan
Bohr’s atomic theory based on the hydrogen emission spectrum
The electrons occupy fixed energy values They do not radiate energy They occupy the ground state They can become excited E2 - E1 = hf
First Ionisation Energy
The minimum energy to remove most loosely-bound electron
from a gaseous atom in its ground state
Ionisation Energy Trend with Element 12 and 15
It has a peak
It is more stable
Half filled and fully filled sublevels
Which is lower in energy: 4s or 3d??
4s
Henry Moseley
Discovered a method of determining the number of protons in the nucleus (atomic number)
Electronegativity
The relative attraction that an atom in a molecule has for the shared pair of electrons in a covalent bond
Intermolecular forces
The attractive forces between molecules
Would a negatively charged rod attract a stream of water
Yes
Molecules arrange themselves with positive pole towards the rod
Would you expect hydrogen sulfide to be soluble in water?
No
Does not form hydrogen bonds with water
What instrumental technique is based on the fact that each element has unique atomic
spectra?
Atomic Absorption Spectrometry
Covalent bond
The sharing of one or more pairs of electrons
Intermolecular forces in propene
Van der Waals forces
Intermolecular forces in propanal
Dipole-dipole forces
Is propanal soluble in water
Yes
Hydrogen binding between the O atom in carbonyl and H atom of water molecule
Henry Moseley
Discovered a method of measuring an element’s atomic number from wavelength of x rays
James Chadwick
Bombarded beryllium with alpha particles which knocked the neutrons out
Neutrons knocked out protons in the paraffin wax detected the neutrons
Protons detected neutrons
Who devised the table of electronegativities
Linus Pauling
