1.1 Atomic structure Flashcards
Isotopes
The same number of protons but different numbers of neutrons
Orbital
region in space where one is likely to find 2 pairs of electron (these have opposite spins to overcome repulsive energy)
Z
Atomic number
A
mass number
Hinesburg uncertainty principle
you cant determine the position or momentum of an electron
relative atomic mass
the average mass of an atom of an element measured on a scale where Carbon-12 is exactly 12
Relative isotope mass
The average mass of an atom of an isotope of an element measured on a scale where carbon-12 is exactly 12.
Relative molecular mass
the average mass of a molecule of an element measured on a scale where carbon 12 is exactly 12
Ionisation energy
it is the measure of an amount of energy needed to remove an electron
first ionisation energy
energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous positive ions
How does shielding affect 1st ionisation?
The more electrons between the positive nucleus and negative electrons being removed- the less energy required as there is a weaker attraction
How does nuclear charge affect 1st ionisation?
the more protons the bigger the attraction between the nucleus and the electrons
How does distance affect 1st ionisation?
the larger the atom, the greater the distance between the nucleus and the electrons and so the weaker the attraction
What is successive ionisation energy?
energy needed for the removal of more than 1 electron from the same atom one after the other. OR the energy needed to remove an electron from each atom/ion in 1 mole of gaseous atom/ion
Key features of successive ionisation energies?
- successive ionisation energies are always greater than the previous ones as an e- is pulled away from a more positive species
- large increases occur when there is a change in shell as there is a big decrease in shielding- can be used to predict the group of an unknown element
