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
